Academic literature on the topic 'Postharvest losses'
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Journal articles on the topic "Postharvest losses"
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Gathambiri, CW, WO Owino, S. Imathiu, and JN Mbaka. "Postharvest losses of bulb onion (Allium cepa L.) in selected sub-counties of Kenya." African Journal of Food, Agriculture, Nutrition and Development 21, no. 02 (March 24, 2021): 17529–44. http://dx.doi.org/10.18697/ajfand.97.20145.
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Inappropriate postharvest practices such as unsuitable harvesting methods and inadequate curing in bulb onion lead to losses. Postharvest losses in bulb onion contribute to food and nutrition insecurity. Although Kenya has suitable environmental conditions for bulb onion production, its productivity is low, which is attributed to pre-and postharvest factors. Information on bulb onion postharvest losses and their causes in the country is scanty which limits the development of postharvest losses reduction strategies. Therefore, this study was carried out in three major bulb onion growing sub-counties of Kenya namely Mt.Elgon, Buuriand KajiadoEastto determine postharvest practices, causes, and factors influencing postharvest losses of bulb onion. A multi-stage sampling design was used to select the study areas and a total of 166respondents were randomly selected. Face-to-face interviews were conducted using a structured questionnaire to collect information on postharvest handling practices, postharvest loss levels, and their causes at farm level. Data were subjected to descriptive and logistic regression analysis using Statistical Package for Social Scientists(SPSS) software version 2.0. Results indicated that 68% of the respondents were males and with an average age of40 years in the three sites. Forty-eight percent of the respondents used leaves toppling, and 25% used drying of upper leaves as maturity indices. About 42% of the respondents used machete (panga) as a harvesting tool which significantly (P<0.05) influenced postharvest losses. Seventy seven percent of the respondents indicated that up to 30% of postharvest losses occurred at farm level. Forty percent of the respondents indicated that bulb onion rots caused 10 % loss at farm level. The level of education and mode of transport (bicycles and donkeys) significantly (P<0.05) influenced postharvest losses. It was concluded that the postharvest losses at farm levelwas30%andwere mainly caused by rotting. Socio-economic characteristics and postharvest handling practices influenced bulb onion losses at farm level. Development of postharvest losses reduction strategies on bulb onions focusing on alleviating rotting through appropriate postharvest handling practices at farm level was recommended.
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Ansah, Isaac Gershon Kodwo, and Bright K. D. Tetteh. "Determinants of Yam Postharvest Management in the Zabzugu District of Northern Ghana." Advances in Agriculture 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/9274017.
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Postharvest loss reduction has received attention in many policy documents across nations to ensure global food security, particularly in developing countries. Many researchers have examined various options for reducing postharvest losses. We contribute our quota to this scientific discourse by using a different approach. We argue that the human element of managing postharvest loss is central and therefore poses the question of what are the characteristics of the farmer who manages postharvest losses better. We examine this question by using a cross section of yam farmers in the Zabzugu district in Northern Ghana and generate a proportional variable called postharvest management, which measures how effective a farmer works to reduce storage losses. We then use a fractional logistic regression model to examine the determinants of postharvest management. A significant result is that subsistence farmers manage postharvest losses better than commercial farmers. Characteristically, the farmer who effectively manages postharvest losses is a young, subsistence farmer, living in or close to a district capital with fewer household members, has attained formal education, and produces more yam. Efforts to reduce postharvest losses require the provision of access roads to remote towns or providing effective storage techniques and training on postharvest management practices.
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Gautam, Shriniwas, Antonio L. Acedo Jr, Pepijn Schreinemachers, and Bhishma P. Subedi. "Volume and value of postharvest losses: the case of tomatoes in Nepal." British Food Journal 119, no. 12 (December 4, 2017): 2547–58. http://dx.doi.org/10.1108/bfj-12-2016-0632.
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Purpose The purpose of this paper is to develop a straightforward method to quantify volume and value of postharvest losses in the tomato postharvest value chain in Nepal and estimate the monetary loss shouldered by value chain actors. Design/methodology/approach The study combines interview data to quantify volume and prices with produce sampling to quantify quality losses, and does this at four nodes of the tomato value chain in Nepal: farmers, collectors, wholesalers, and retailers to estimate volume and value of postharvest losses. Findings Almost one-fourth of the total tomato harvest weight that enters the value chain is lost before it reaches consumers, and other one-fifth is traded by the value chain actors at reduced price due to quality damage. The total volume of postharvest loss (weight and quality loss) is not the same for all value chain actors and the average monetary loss ranges from 4 percent of gross revenues for farmers to 12 percent for wholesalers. Practical implications A standard method to account for both physical weight losses and quality losses of horticultural produce is lacking in estimates of the monetary value of postharvest losses for horticultural crops. Knowing such losses is essential for postharvest technology generation, promotion, and adoption. This study provides a framework that can be adopted and improved in future loss assessment studies for estimating the volume and value of postharvest losses in a horticultural value chain. Originality/value The uniqueness of the method used in this study is that it combines interview data to estimate price and volume with produce sampling to quantify quality losses, and does this at four nodes of the value chain: farmers, collectors, wholesalers, and retailers. This method could become a standard approach for assessment of postharvest weight and quality losses and to estimate the monetary value of total postharvest losses in the value chain for horticultural crops.
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Arah, Isaac Kojo, Harrison Amaglo, Ernest Kodzo Kumah, and Hayford Ofori. "Preharvest and Postharvest Factors Affecting the Quality and Shelf Life of Harvested Tomatoes: A Mini Review." International Journal of Agronomy 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/478041.
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Tomato production can serve as a source of income for most rural and periurban producers in most developing countries of the world. However, postharvest losses make its production unprofitable in these parts of the world. Postharvest losses in tomatoes can be as high as 42% globally. Postharvest losses in tomatoes can be either quantitative or qualitative. Even though emphasis in crop research nowadays is increasing shifting from quantity to quality of produce, there is still little improvement in the quality of commercially produced tomato varieties, hence resulting in high quality losses. From the study it was discovered that the postharvest quality status of tomatoes partly depended on some preharvest practices carried out during production. Some of these factors are fertiliser application, pruning, maturity stage, cultivar selection, and irrigation. Using best postharvest handling practices or factors such as temperature, relative humidity, gases in storage, postharvest calcium chloride application, and physical handling procedures to maintain the quality after harvest was also critical. It was concluded by this study that understanding and managing both preharvest and postharvest factors properly will reduce the postharvest quality losses in tomatoes.
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Mvumi, Brighton, Learnmore Tatenda Matsikira, and Jackqeline Mutambara. "The banana postharvest value chain analysis in Zimbabwe." British Food Journal 118, no. 2 (February 1, 2016): 272–85. http://dx.doi.org/10.1108/bfj-08-2014-0293.
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Purpose – The purpose of this paper is to evaluate the banana industry in Zimbabwe focusing on postharvest losses along the value chain (VC). Design/methodology/approach – The study evaluated the banana industry in Zimbabwe focusing on postharvest losses along the VC. Findings – Total postharvest losses for 2011-2012 were estimated to be 24-27 per cent of total production with a minimum economic loss of USD69,983/annum/firm, and a total loss of more than USD500,000/annum between the VCs analysed. The bulk of the losses occurred at farm level during handling and transportation. The major factors contributing to banana postharvest losses were: unreliable transport, poor communication and coordination between producers and processors; lack of or inefficient temperature management and poor sanitation. Practical implications – The study identified production capacity, quality and branding as opportunities and challenges in the banana industry. Currently, there is a 40 per cent unmet local demand for bananas and hence there are no exports. If modern banana handling systems are employed and more research and development is carried out along the VC, postharvest losses can be reduced significantly, resulting in increased income and potential expansion of the industry. Originality/value – This is the first known attempt to analyse the banana VC in southern Africa and quantify postharvest losses.
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Kader, Adel A. "655 Role of Postharvest Storage in Meeting World Food Needs." HortScience 35, no. 3 (June 2000): 511B—511. http://dx.doi.org/10.21273/hortsci.35.3.511b.
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Postharvest losses of horticultural perishables between the production and retail distribution sites are estimated to range from 2% to 23%, depending on the commodity, with an overall average of about 12% of what is shipped from U.S. production areas to domestic and export markets. Estimates of postharvest losses in developing countries are two to three times the U.S. estimates. Losses in dried grains, legumes, nuts, fruits, vegetables, and herbs and spices range from 1% to 10%, depending on their moisture content, temperature and relative humidity of transport and storage facilities, and protection against pathogens and insects. Reduction of these losses can increase food availability to the growing population, decrease the area needed for production, and conserve natural resources. Strategies for loss prevention include use of genotypes that have longer postharvest-life, use of an integrated crop management system that results in good keeping quality of the commodity, and use of the proper postharvest handling system that maintains quality and safety of the products. Biological (internal) causes of deterioration include respiration rate, ethylene production and action, rates of compositional changes, mechanical injuries, water loss, sprouting, physiological disorders, and pathological breakdown. The rate of biological deterioration depends on several environmental (external) factors, including temperature, relative humidity, air velocity, and concentrations of carbon dioxide, ethylene, and oxygen. Socioeconomic factors that contribute to postharvest losses include governmental regulations and policies, inadequate marketing and transportation systems, unavailability of needed tools and equipment, lack of information, and poor maintenance of facilities. Although minimizing postharvest losses of already produced food is more sustainable than increasing production to compensate for these losses, less than 5% of the funding of agricultural research is allocated to postharvest research areas. This situation must be changed to increase the role of postharvest loss reduction in meeting world food needs.
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Usman, Muhammad, Maryam Razzaq, Rana Ahsan Rehman Khan, Muhammad Abdur Rehman, Muhammad Moaaz Ali, Shaista Gull, Ahmed Fathy Yousef, Muhammad Adnan, Sezai Ercisli, and Kirill S. Golokhvast. "Factors Affecting Postharvest Losses of Sesame (Sesamum indicum L.) and Their Mitigation Strategies." Agronomy 12, no. 10 (October 11, 2022): 2470. http://dx.doi.org/10.3390/agronomy12102470.
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Current postharvest activities in the sesame value chain are prompting colossal losses, which reduce overall global productivity. This review portrays losses in sesame during various processing stages, from grain harvesting to marketing and transformation of crop seed into oil. Such losses in sesame not only reduce yield but also have an impact on the economy of its production territories. The loss in productivity is because the majority of farmers don't use adequate harvesting, packaging, or handling technologies to manage on-farm produce. Also, there is a lack of knack for minimizing postharvest losses. Therefore, the study penlights the inevitability of increasing production by raising productivity and quality while giving mitigation strategies to reduce postharvest losses. Elevating standardized productivity with accurate postharvest management is the only substitute for the gap between the global productivity average and the overall production potential of sesame.
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Kudzai Mukumbi, Fungisai Chebanga, and Moses Mutetwa Tuarira Mtaita. "Postharvest losses to agricultural product traders in Mutare, Zimbabwe." Journal of Scientific Agriculture 2 (January 26, 2018): 26. http://dx.doi.org/10.25081/jsa.2018.v2.892.
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The study examined the nature and causes of postharvest losses incurred by formal and informal traders in Mutare urban. A survey was conducted where questionnaires were administered to various respondents in the formal and informal sector of fruits and vegetables. The research study assessed the profitability of trading in fruits and vegetables to formal and informal traders. It also assessed traders’ perception of the losses of fruits and vegetables and further determined the possible ways of reducing these postharvest losses so as to enhance profitability in the sector. The study from a sample of 34 respondents revealed that both formal and informal traders experience losses during storage and transportation of goods. Losses incurred during storage were due to the unavailability of proper storage facilities specifically to informal traders. Furthermore, postharvest losses were also resulting from excessive exposure of crops to sunlight, poor packaging, poor carrying containers, attacks by insect pests as well as microbial or disease attacks. Postharvest losses affect profitability and growth of the fruits and vegetables sectors. There is need for farmers to improve on the quality of their produce and harvesting practices as emphasized by traders as they suffered losses as a result of poor quality goods supplied. Further postharvest practices should be improved by traders with special emphasis on adequate storage, handling and proper transportation of goods.
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Gummert, M. "IMPROVED POSTHARVEST TECHNOLOGIES AND MANAGEMENT FOR REDUCING POSTHARVEST LOSSES IN RICE." Acta Horticulturae, no. 1011 (November 2013): 63–70. http://dx.doi.org/10.17660/actahortic.2013.1011.6.
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Munhuweyi, Karen, Umezuruike Linus Opara, and Gunnar Sigge. "Postharvest losses of cabbages from retail to consumer and the socio-economic and environmental impacts." British Food Journal 118, no. 2 (February 1, 2016): 286–300. http://dx.doi.org/10.1108/bfj-08-2014-0280.
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Purpose – The purpose of this paper is to quantify the incidence of postharvest losses of cabbage at retail purchase and during consumer simulated storage. Design/methodology/approach – Physical losses, changes in quality and nutritional value were determined using produce from three different retail outlets in South Africa. Economic losses and the environment impact associated with postharvest losses of cabbage were estimated. Findings – After seven days in storage, high incidence of postharvest losses occurred, ranging from 12 per cent under cold storage to 46 per cent under ambient conditions. These losses were equivalent to over R10 million (∼US$1 million) per annum, while the equivalent wasted fresh water was estimated to be sufficient to meet the needs of over 217,000 per annum. Research limitations/implications – Study was only conducted in one town and to get the real impact of the losses the research should cover a wider coverage area. Originality/value – Cabbage is one of the most widely consumed vegetables globally and this is the first research effort to quantify the magnitude of postharvest losses. A multi-parameter approach was applied to estimate the socio-economic and environmental impacts of losses.
Dissertations / Theses on the topic "Postharvest losses"
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Greeley, M. "Rice in Bangladesh : Postharvest losses, technology and employment." Thesis, University of Sussex, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373146.
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Meyer, Celeste. "Carbohydrates and leaf blackening of Protea cut flowers." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53320.
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Thesis (MScAgric)--Stellenbosch University, 2003.ENGLISH ABSTRACT: Protea cut flowers are exported worldwide but the vase life of some species and cultivars is considerably shortened by post-harvest leaf blackening. Research has established carbohydrate depletion to be positively correlated with this disorder. Consequently, a study had been made of the carbohydrate status of various species and cultivars, as well as the effect of supplemental glucose (pre and post-storage) on leaf blackening. Glucose, fructose, sucrose and starch concentrations of various Protea species and cultivars held in water were measured at harvest, and again at leaf blackening initiation. All measured carbohydrates declined significantly in 'Carnival', 'Pink Ice' and 'Sheila'. In 'Cardinal' all carbohydrate concentrations decreased significantly, except the sucrose concentration in the inflorescence. 'Susara' and 'Ivy' had very high initial carbohydrate concentrations in the leaves which decreased significantly. The very high initial carbohydrate concentrations in the inflorescence of 'Ivy' declined significantly. 'Brenda' differed from the other cultivars and species in that glucose concentrations increased over time. Carbohydrate concentrations of most of the tested proteas declined significantly from harvest to the initiation of leaf blackening. This highlighted the dependence of the leaves and inflorescence on the carbohydrate reserves, further substantiating the carbohydrate depletion theory. The inflorescences were characterized by high fructose and glucose concentrations and low sucrose concentrations when compared to the leaves. It was hypothesized that glucose pulsing and cold storage at 1°C for three weeks would significantly reduce leaf blackening. 'Brenda', 'Cardinal', 'Carnival', 'Pink Ice', 'Susara ' and 'Sylvia' had significantly less leaf blackening with glucose treatments of 4 and 10%. Leaf blackening of 'Sheila', P. cynaroides and P. grandiceps was not significantly reduced by glucose pulsing. P. magnifica showed a small, but significant, reduction in leaf blackening in response to the 3, 6 and 9% treatments after 10 days only, but despite this, leaf blackening was unacceptably high. 'Pink Ice' harvested at the soft tip stage had less leaf blackening than those harvested open or closed. Toxicity symptoms on the leaves, and in some instances flowers, were observed at higher glucose concentrations (8 and 10%) onP. grandiceps, P. cynaroides, 'Cardinal' and 'Sheila'. All glucose treatments resulted in toxicity symptoms on P. magnifica. A decrease in nonstructural carbohydrates post-harvest apparently occurs in all proteas but it appears that only members of the Ligulatae respond to glucose. Glucose pulsing followed by cold storage at 1°C for three weeks in combination with post-storage glucose vase solutions, significantly reduced leaf blackening of some Protea cultivars. Glucose (1 and 2%), with hypochlorite, significantly delayed leaf blackening in 'Cardinal' and 'Sylvia' after seven days. Leaf blackening of 'Brenda', 'Carnival', 'Pink Ice' and 'Susara' was not significantly reduced by the glucose vase solutions. Other disinfectants, in combination with the sugar treatments, need to be evaluated since the hypochlorite treatment had a dehydrating effect on all the cultivars and resulted in increased leaf blackening. Carbohydrate supplementation of protea flowers with glucose, pre and post-storage, will help meet the post-harvest carbohydrate requirements of certain Protea cultivars and species to an extent. Glucose treatments must be seen in conjunction with maintaining the cold chain and when combined with cold chain maintenance, can extend the storage and vase life.
AFRIKAANSE OPSOMMING: Protea snyblomme word wêreldwyd uitgevoer alhoewel die vaasleeftyd van sommige spesies en kultivars beduidend verkort word deur na-oes loof verbruining. Navorsing het koolhidraatverbruik positief gekorreleer met hierdie probleem. Gevolglik is 'n studie gemaak van die koolhidraatstatus van verskeie spesies en kultivars asook die effek van addisionele glukose (voor en na opberging) op loofverbruining. Glukose, fruktose, sukrose en stysel konsentrasies van verskeie Protea spesies en kultivars wat in water gehou is, is bepaal met oes en weer met die eerste tekens van loofverbruining. Al die gemete koolhidraatkonsentrasies het beduidend afgeneem in 'Carnival', 'Pink Ice' en 'Sheila'. In 'Cardinal' het al die koolhidraatkonsentrasies beduidend afgeneem, behalwe vir die sukrosekonsentrasie in die blom. 'Susara' en 'Ivy' het baie hoë begin koolhidraatkonsentrasies in die blare wat beduidend afneem. Die baie hoë inisiële koolhidraatkonsentrasies in die blom van 'Ivy' neem beduidend af met tyd. 'Brenda' verskil van die ander kultivars en spesies deurdat die glukosekonsentrasies toeneem met tyd. Koolhidraatkonsentrasies van die meeste getoetste proteas neem beduidend af vanaf oes totdat die eerste tekens van loofverbruining verskyn. Dit het die afhanklikheid van die blare en blom op die koolhidraatreserwes beklemtoon en daardeur verder die koolhidraatteorie ondersteun. Die blomme is gekarakteriseer deur hoë fruktose- en glukosekonsentrasies en lae sukrosekonsentrasies wanneer dit met die blare vergelyk is.Die hipotese is gestel dat die voorsiening van glukose, vir 'n aantal ure, gekombineerd met koue opberging by 1°C vir drie weke loofverbruining beduidend sal verminder. 'Brenda', 'Cardinal', 'Carnival', 'Pink lee', 'Susara' en 'Sylvia' het beduidend minder loofverbruining met glukose behandelings tussen 4 en 10%. Loofverbruining van 'Sheila', P. cynaroides en P. grandiceps is nie beduidend verminder deur glukose behandelings nie. P. magnifica het 'n klein, maar beduidende verlaging in loofverbruining getoon met die 3, 6 en 9% behandelings na 10 dae, maar ten spyte hiervan was loofverbruining onaanvaarbaar hoog. 'Pink lee' is geoes by die sagte punt stadium en het minder loofverbruining gehad as blomme wat oop of toe geoes is. Toksisiteitsimptome op die blare, en in sommige gevalle blomme, is waargeneem met hoër glukose konsentrasies (8 en 10%) op P. grandiceps, P. cynaroides, 'Cardinal' en 'Sheila'. Alle glukosebehandelings het toksisiteitsimptome tot gevolg gehad op P. magnifica. 'n Afname in nie-strukturele koolhidrate na oes kom waarskynlik voor in alle proteas maar dit wil voorkom of slegs lede van die Ligulatae positief reageer op glukose. Glukosebehandeling gevolg deur koue opberging by 1°C vir drie weke in kombinasie met na-stoor glukose vaasoplossings het loofverbruining van sommige Protea kultivars beduidend verminder. Glukose (l en 2%), saam met hipoehloriet, het loofverbruining beduidend verminder in 'Cardinal' en 'Sylvia' na sewe dae. Loofverbruining van 'Brenda', 'Carnival', 'Pink lee' en 'Susara' is nie beduidend verminder deur die glukose vaasoplossings nie. Ander ontsmettingsmiddels in kombinasie met die suikerbehandelings moet geëvalueer word aangesien die hipoehlorietbehandeling 'n dehidrerende effek op al die kultivars gehad het en 'n toename in loofverbruining tot gevolg gehad het. Byvoeging van glukose by proteablomme, voor en na opberging, sal tot 'n mate help om in die na-oes koolhidraatbehoeftes van sekere Protea kultivars en spesies te voorsien. Glukosebehandelings moet saam met die beheer van die koueketting gesien word en wanneer gekombineerd met koueketting beheer kan dit opberg en vaasleeftyd verleng.
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Tasneem, Azra. "Postharvest treatments to reduce chilling injury symptoms in stored mangoes." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81444.
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The market life of many fruits and vegetables can be extended through storage at low temperatures. Chilling injury (CI) is a major postharvest storage problem for tropical commodities. Storing these products at temperatures below their critical temperature may result in severe physiological disorders known as CI symptoms. Mangoes (Mangifera indica. L) are susceptible to CI when stored below 12 °C. Visual CI symptoms include uneven ripening, surface pitting, discoloration, shriveling and scalding. Research has been conducted to overcome these serious problems using various postharvest treatments such as hot water, methyl jasmonate (MJ) or diphenylamine (DPA) with some reduction of the incidence of CI symptoms in fruits and vegetables.Experiments were performed to assess and compare the potential of the above-mentioned postharvest treatments to reduce the CI symptoms on mango cv. Kent. The obtained results indicated that MJ- and DPA-treatments gave significantly greater percentage of marketable fruits.
Experiments were also conducted with mangoes cv. Tommy Atkins treated with MJ and DPA before storing at low temperatures (1, 4, 7 and 10°C). The chemical treatments were successful at reducing CI symptoms of mangoes. Fruit decay was reduced during subsequent ripening. MJ-treated fruits had lower mass loss and higher total soluble solids (TSS) than the control treatment. The overall quality of MJ- and DPA-treated fruits was good with lower surface pitting and scalding compared with the control treatment. The best results were obtained at storage temperatures of 7 and 10°C. Both MJ and DPA postharvest treatments can reduce CI symptoms in mangoes cvs. Kent and Tommy Atkins when the mangoes are stored at below critical temperature.
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Lu, Jianbo. "Quantifying non-uniformity in hot air treatment using tomato as a test material for postharvest quality and disease control." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115694.
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The influence of uniformity of heat transfer with respect to the effect of heat treatment was investigated by correlating engineering parameters with the quantified heat treatment effects. Differences in treatment effect in terms of quality, anti-pathogen and chilling injury (CI) control properties among commodities was studied by exposing them to different target temperatures. Similar effects were also evaluated and quantified within an individual commodity by a custom-designed device. This device, whose design parameters were based on a heat transfer simulation, insured that one hemisphere of a tomato was exposed to air at 39°C and 0.24 m s-1; while the other hemisphere was exposed to air at a lower temperature with a velocity of0.24 m s-1 or 0.12 m s-1.Single-temperature heat treatment was most effective in limiting pathogen development and varied according to the parameter measured: 38°C for hypersensitive response (HR), 36°C for tissue breakdown, 36°C, 38°C or 39°C for mycelium abundance, and 38°C or 39°C for lesion size. Bilateral differences in temperature across the fruit significantly affected disease control: decreasing temperature differences significantly improved the uniformity of disease control.
Some of the effects of heat treatment on tomato quality, such as color development and resistance to CI, appear to be localized. A significant difference in redness was identified between heated parts and unheated parts of tomato fruits immediately after treatment; and the differences persisted during storage. Differences in lightness and chroma were noted on day 4. Delay in ripening caused by heat treatment was confirmed through the higher TA and TSS values of heated tomatoes or heated portion of partially heated tomatoes.
The heated parts of tomatoes showed a stronger resistance to chilling injury. The effective temperature control range for CI was wide, but temperatures higher than 39.5°C for 23 h hot air treatment could lead to adverse effects.
Differences in physiological effects between hemispheres in two chambers was reduced by directly decreasing the temperature difference between upper and lower chambers or relatively increasing the heating air flow rate, highlighting the importance of improving the uniformity of air flow around each individual treated fruit.
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Stephens, Iain Andrew. "Leaf blackening of proteas." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/49768.
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Dissertation (PhD (Agric))--University of Stellenbosch, 2003.ENGLISH ABSTRACT: Leaf blackening is a particular problem limiting vase life and marketability of Protea cut flowers. This research investigated suppression of Protea leaf blackening with a specific focus on Protea cv. Sylvia (P. eximia x P. susannae) cut flowers. Leaf blackening decreased significantly with decreasing storage temperatures m 'Sylvia' proteas and this was attributed to lower respiration rate and conservation of carbohydrate. Low storage temperatures were beneficial in short term handling procedures encountered during airfreight. However, use of low temperatures alone during the longer sea freight period was unsatisfactory in either maintaining or extending 'Sylvia' protea vase life. Cooling of 'Sylvia' proteas under vacuum significantly suppressed leaf blackening and was of greater benefit than forced air cooling. Although removal of the uppermost leaves delayed leaf blackening in short term storage no significant benefit was found for longer storage periods. Girdling directly beneath the 'Sylvia' protea flowerhead significantly reduced leaf blackening and in combination with low storage temperatures (O°C) enabled a significant extension in both storage and vase life of 'Sylvia' proteas. 'Sylvia' proteas did not exhibit a climacteric respiration peak during 96 h storage at O°C. Exposure to ethylene did not increase Protea leaf blackening or have a detrimental effect on vase life of either proteas or pincushions evaluated. No beneficial response to sucrose supplementation was found in 'Sylvia' proteas. Analysis of the sugar content of both flowerhead and leaves indicated that glucose supplementation might be of benefit and was investigated. Holding solutions of 2.5 % glucose significantly extended vase life due to a significant reduction in leaf blackening. Vase life was terminated due to flowerhead collapse instead of leaf blackening for the first time in 'Sylvia' protea cut flowers. Vase life was significantly extended by 2:3% glucose pulse solutions and leaf blackening significantly suppressed with increasing glucose pulse concentration. Solution uptake was facilitated by use of high intensity PAR lights in the early morning and was attributed to increased stomata opening and a consequent increase in both transpiration and glucose solution uptake. The faster uptake of glucose solutions in shoots harvested in the afternoon was attributed to higher shoot temperatures and consequent transpiration rate to those harvested in the morning. There was a significant reduction in uptake time with increasing pulse temperature, which enabled vacuum cooling to be performed earlier further benefiting storage and vase life extension. Enclosure of 'Sylvia' proteas in polyethylene (PE) lined cartons did suppress leaf blackening in non-pulsed shoots. However, this had no practical significance on useful vase life, which was terminated at this point due to excessive leaf blackening. Water loss appears to have a minimal influence on 'Sylvia' protea leaf blackening. Shading at four and three weeks prior to harvest coincided with a period of significant flowerhead dry mass increase. It is thought that shading at this point, concurrent with an increased carbohydrate demand by the developing flower head resulted in a temporary limitation in carbohydrate supply resulting in the appearance of preharvest leaf blackening. It would appear that proteas do not store large quantities of carbohydrate. Although accentuating winter light conditions by shading did result in a decrease in carbohydrate content the fact that carbohydrate content was already low precluded shading from having a significant impact on postharvest leaf blackening. The finding that glucose was beneficial in extension of both storage and vase life of 'Sylvia' proteas directed research into its use for other Protea and Leucospermum cut flowers. Significant differences in the response to glucose supplementation were found in both Protea and Leucospermum (pincushions). The significant difference in sensitivity to glucose concentration in 'Pink Ice' proteas (phytotoxic at 2:4%) and 'Susara' proteas (no apparent toxicity), in conjunction with a lack of response in 'Cardinal' proteas, a hybrid from the same parents as 'Sylvia' indicates the need to direct future research to individual cultivars. Glucose supplementation had no beneficial effect on vase life of 'Scarlet Ribbon' and 'Tango' pincushions, whilst significantly extending vase life of 'Cordi', 'Gold Dust', 'High Gold' and 'Succession' pincushions.
AFRIKAANSE OPSOMMING: Blaarverswarting is 'n spesifieke probleem wat die vaasleeftyd en die bemarkbaarheid van Protea snyblomme beperk. In hierdie navorsing is ondersoek ingestel na die onderdrukking van Protea blaarverswarting met spesifieke fokus op die snyblomme van die kv. Sylvia (P. eximia x P. susannae). Die voorkoms van blaarverswarting by 'Sylvia' het merkbaar afgeneem tydens die verlaging van bergingstemperature. Hierdie afname is toegeskryf aan 'n laer respirasietempo en die behoud van koolhidrate. Lae bergingstemperature in die korttermyn hantering van die produk tydens lugvrag was voordelig. Die gebruik van lae temperature, slegs tydens die langer verskeepingsperiode, was egter onbevredigend vir vaasleeftyd verlenging en onderhoud van 'Sylvia' protea. Die afkoeling van 'Sylvia' proteas onder vakuum het blaarverswarting in 'n groot mate onderdruk en het beter resultate gelewer as geforseerde lugverkoeling. Alhoewel die verwydering van die heel boonste blare blaarverswarting by korttermynopberging vertraag het, het dit geen merkbare voordele vir langer bergingsperiodes ingehou nie. Ringelering direk onder die blomkop van die 'Sylvia' protea het blaarverswarting aansienlik verminder, en saam met lae bergingstemperature (O°C) het dit 'n merkbare verlenging in beide die bergingstyd en die vaasleeftyd van 'Sylvia' proteas teweeggebring. 'Sylvia' proteas het geen klimakteriese respirasiekruin tydens 'n bergingsperiode van 96 uur teen O°C getoon nie. Blootstelling aan etileen het nie die Protea blaarverswarting laat toeneem of 'n nadelige effek op die vaasleeftyd van die proteas of speldekussings wat geevalueer is, gehad nie. Geen voordelige reaksie op sukrose-byvoeging is in 'Sylvia' proteas gevind nie. 'n Analise van die suikerinhoud van beide die blomkoppe en die blare het aangetoon dat 'n glukose-byvoeging moontlik voordelig kon wees, en hierdie aspek is ondersoek. Met stooroplossings van 2,5 % glukose is die vaasleeftyd aansienlik verleng omdat daar 'n merkbare afname in blaarverswarting was. Vir die eerste keer in die geval van die 'Sylvia' protea, het die vaasleeftyd van die snyblomrne tot 'n einde gekom omdat die blornkoppe uitmekaar gebreek het en nie omdat blaarverswarting ingetree het nie. Die vaasleeftyd is aansienlik verleng met ~ 3% glukose-pulsoplossings, en blaarverswarting is merkbaar onderdruk met die verhoging van hierdie oplossings se glukosekonsentrasie. Die opname van die oplossings is gefasiliteer deur hoe intensiteit PAR (fotosinteties-aktiewe radiasie) ligte vroeg in die oggend, en is toegeskryf daaraan dat meer huidmondjies oopgegaan het. Dit het gelei tot 'n toename in transpirasie en 'n toename in die opname van die glukose-oplossing. Die feit dat glukose-oplossings vinniger opgeneem is deur lote wat in die middag geoes is, is toegeskryf daaraan dat loottemperature dan hoer is as soggens en gevolglik lei tot 'n vinniger transpirasietempo. Daar was 'n merkbare afname in die opnametyd wanneer die temperatuur van die pulsoplossings verhoog is. Vakuumafkoeling kon dus vroeer toegepas word, wat 'n verlenging in bergingstyd en vaasleeftyd tot gevolg gehad het. Verpakking van 'Sylvia' proteas in kartonne wat met poli-etileen uitgevoer is, het blaarverswarting van lote wat nie aan pulsering onderwerp is nie, onderdruk. Hierdie maatreel het egter geen praktiese waarde met betrekking tot vaasleeftyd nie; die vaasleeftyd het tot 'n einde gekom as gevolg van omvangryke blaarverswarting. Dit lyk asof waterverlies weinig invloed het op die blaarverswarting van' Sylvia' proteas. Die vermoede bestaan dat lae koolhidraatvlakke proteas ontvanklik maak vir blaarverswarting. Alhoewel die beklemtoning van winterligtoestande deur beskaduwing gelei het tot 'n afname in koolhidraatinhoud, was hierdie inhoud reeds laag en blaarverswarting na die oes is nie beinvloed nie. Beskaduwing tydens die vier en drie weke voor oestyd het saamgeval met 'n tydperk van aansienlike toename in die droe massa van die blomkop. Die vermoede bestaan dat beskaduwing tydens hierdie fase, saam met die toename in die ontwikkelende blomkop se behoefte aan koolhidrate, aanleiding gegee het tot 'n tydelike beperking in koolhidraatvoorraad wat die voorkoms van blaarverswarting voor die oes tot gevolg gehad het. Die bevinding dat glukose voordelig is vir die verlenging van beide die bergingstyd en die vaasleeftyd van 'Sylvia' proteas het die navorsing gerig om ook ondersoek in te stel na die gebruik daarvan vir ander Protea en Leucospermum snyblomme. Merkbare veranderinge is gevind in die reaksie op glukosebyvoegings in beide Protea en Leucospermum (speldekussings). Die opmerklike verskil in sensitiwiteit vir glukosekonsentrasie in 'Pink Ice' proteas (fitotoksies by ~ 4%) en 'Susara' proteas (geen klaarblyklike toksisiteit), saam met 'n gebrek aan reaksie by 'Cardinal' proteas, 'n hibried van dieselfde ouers as 'Sylvia', dui aan dat verdere navorsing op individuele kultivars toegespits sal rnoet word. Glukosebyvoegings het geen voordelige uitwerking op die vaasleeftyd van 'Scarlet Ribbon' en 'Tango' speldekussings gehad nie, terwyl dit die vaasleeftyd van 'Cordi', 'Gold Dust', 'High Gold' en 'Succession' speldekussingkultivars merkbaar verIeng het.
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Matare, Tsaurayi Edwin. "Postharvest losses and changes in physico-chemical properties of fruit (peaches, pears and oranges) at retail and during post-purchase storage." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71974.
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Thesis (MScFoodSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Postharvest fruit loss is a major challenge in addressing food security, sustainable management of resources and profitability of agribusiness. The incidence of postharvest loss and changes in physico-chemical properties of three types of fruit (peaches, pears and oranges) were evaluated at retail and during post-purchase storage. The amount of physical loss at the three retail outlets studied ranged from 3.61% to 18.09% among the fruit types, with the highest incidence occurring in peaches. The estimated annual national physical loss at retail was 418 tons for pears, 1000 tons for oranges, and 7 240 tons for peaches. Based on the WHO recommended 146 kg per capita per year consumption of fruit, the total loss of the three types of fruit was sufficient to meet the dietary fruit requirements of 50 000 people per annum. Similarly, based on the recommended daily allowance of 50 mg of ascorbic acid, these losses could meet the annual vitamin C needs of 82 000 people. The estimated monetary value of the losses at retail ranged from R2.2 million to R96.87 million per annum depending on fruit type and retail outlet. The land wasted to produce lost fruits was 1965 ha while energy wasted was 32.77 x 106 MJ. Greenhouse gas emission of the losses was 2870 tons CO2eq and total water footprint 68 0000 m3. Losses were mainly due to the presence of severe physical damage, rots and physiological disorders. There were significant variations in physico-chemical properties of fruit of the same type from different retail outlet. Although ambient temperature storage improved fruit colour and some chemical constituents responsible for palatability, it was associated with high physical and nutritional (vitamin C) losses. Results from this study show that appropriate harvesting maturity, packaging and maximum care in fruit handling is essential in reducing postharvest losses. Efficient cold chain management and fruit inspection for rots and damages could help to reduce subsequent spoilage at retail and during post-purchase storage. Given that the incidence of postharvest fruit loss observed at retail is the result of cumulative effects along the supply chain, further studies are warranted to map fruit history and magnitude of losses along the value chain.
AFRIKAANSE OPSOMMING: Naoesvrugteverlies is ‟n groot uitdaging in die strewe na voedselsekerheid, volhoubare hulpbronbestuur en winsgewende landbousake. Die voorkoms van naoesverlies sowel as fisiko-chemiese naoesveranderinge by drie vrugtesoorte (perskes, pere en lemoene) is gevolglik by kleinhandelsafsetpunte én gedurende berging ná aankoop beoordeel. Die graad van fisiese verlies by die drie betrokke kleinhandelspunte het gewissel van 3,61% tot 18,09% tussen die vrugtesoorte, met die hoogste verlies by perskes. Die geraamde jaarlikse nasionale fisiese verlies by die kleinhandelspunte was 418 ton pere, 1 000 ton lemoene en 7 240 ton perskes. Op grond van die Wêreldgesondheidsorganisasie se aanbevole jaarlikse vrugte-inname van 146 kg per persoon, was die totale verlies van die drie vrugtesoorte genoeg om aan die vrugtedieetvereistes van 50 000 mense per jaar te voldoen. Op grond van die aanbevole daaglikse inname van 50 mg askorbiensuur, kan hierdie verlies eweneens in die jaarlikse vitamien C-behoeftes van 82 000 mense voorsien. Die geraamde geldwaarde van die verlies by die kleinhandelspunte strek van R2,2 miljoen tot R96,87 miljoen per jaar, na gelang van die vrugtesoort en bepaalde kleinhandelspunt. Die vermorste grond om die verlore vrugte te produseer, was 1 965 ha, terwyl energievermorsing op 32,77 x 106 MJ te staan gekom het. Kweekhuisgasvrystellings met betrekking tot die verlies was 2 870 ton CO2e, en die totale watervoetspoor 68 0000 m3. Vrugteverlies kon hoofsaaklik aan ernstige fisiese skade, verrotting en fisiologiese afwykings toegeskryf word. Daar was beduidende variasies in die fisiko-chemiese eienskappe van dieselfde vrugtesoort by verskillende kleinhandelaars. Hoewel berging by omgewingstemperatuur vrugtekleur en bepaalde chemiese komponente vir smaaklikheid verbeter, word dit ook met groot fisiese en voedingstof- (vitamien C-) verliese verbind. Die resultate van hierdie studie toon dat toepaslike oesrypheid, die regte verpakking en maksimum sorg in vrugtehantering noodsaaklik is om naoesverlies te verminder. Doeltreffende koelkettingbestuur en vrugte-inspeksie vir verrotting en skade kan latere bederf by kleinhandelsafsetpunte sowel as gedurende berging ná aankoop help beperk. Aangesien die naoesvrugteverlies wat by die kleinhandelspunte waargeneem is uit kumulatiewe faktore in die verskaffingsketting spruit, is verdere studies nodig om vrugtegeskiedenis na te spoor en die omvang van die verlies in die algehele waardeketting te bepaal.
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Cortbaoui, Patrick. "Assessment of precooling technologies for sweet corn." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84020.
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Sweet corn is classified among highly perishable horticultural commodities. Thus, it can be deteriorated rapidly after harvest resulting in high loss and poorer produce quality. Sweet corn's sugar loss is about four times higher at 10°C compared to 0°C. Precooling, immediately after harvest, has shown to be an effective method to maintain the quality for a wide range of fresh fruits and vegetables during storage. Further, this method leads to reduction in metabolism and respiration rate of the produce, retardation of its senescence, and inhibition of growth of pathogens. In addition to diminishing postharvest losses of the produce, efficient precooling is required for increasing the length of duration of marketing time for better profitability.Precooling of sweet corn was accomplished by three main methods including forced-air, water and vacuum cooling. Operating parameters such as temperature, pressure, orientation of corn cobs, air flow rate and water flow pattern were defined and studied for optimization. The assessment and comparison of the performance of precooling systems was achieved by determining the effect of these parameters on half cooling time and quality of the produce during storage for 7 and 21 days at 1°C and 90-95% RH. In addition, room cooling method was also tested and compared to the three precooling systems. The use of three sweet corn cultivars was important to compare their quality response to different cooling methods.
Experiments were performed on a lab-scale vacuum cooler and modified forced-air and water cooler systems. The results showed that changing the cob orientation perpendicular to the direction of flow medium, using higher air flow rate in forced-air cooling and immersed water flow pattern in water cooling, can significantly reduce the half cooling time of the produce. Finally, the best method to be recommended for precooling sweet corn is by using hydrocooling which results in superior quality produce and minimum time.
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Munhuewyi, Karen. "Postharvest losses and changes in quality of vegetables from retail to consumer : a case study of tomato, cabbage and carrot." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71946.
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Thesis (MScFoodSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Postharvest losses of three different vegetables (tomato - a fruit, cabbage - a leaf and carrot - a root vegetable) were investigated directly after retail purchasing and during consumer simulated storage. To conduct this study, three retail outlets (2 supermarkets and an outdoor market) were selected in Stellenbosch, South Africa. Retail prices of each vegetable were recorded from each respective Outlet. Surrounding environmental conditions (air temperature and relative humidity) at retail and during simulated consumer storage were also monitored. Vegetable postharvest losses were determined by quantifying the incidence of physical loss and changes in physico-chemical properties (colour, firmness, weight loss, ascorbic acid, total pigments, total soluble solids, titratable acid and proximate composition) over time. The percentage losses observed were then used to estimate the associated economic and environmental resource impacts of postharvest vegetable losses at the national level. Vegetable losses immediately at retail purchase were 14.56%, 21.21% and 17.93% for tomato, cabbage and carrot, respectively. The estimated combined volume lost for all three vegetables at national level was approximately 26 460 t valued at R33.70 million. Overall economic loss was highest for tomatoes and least for carrots. The magnitude of the losses observed differed for all the outlets. Vegetable losses were mostly high for the produce from the outdoor market compared to the supermarkets during storage. Throughout the whole trial, mechanical damage accounted for at least 50 to 70% of the losses while the remainder was due to decay and insect damage. Post retail storage temperature; ambient (22–25ºC) vs. cold store (0ºC and 10–12 ºC) had a significant (P<0.05) effect on the vegetable losses. This was for both quantitative and qualitative attributes. Losses for tomato and cabbage were 18.52% and 16.67% after 3 days while carrot losses were 11.83% at 7 days after having been kept in the recommended respective cold storage temperatures. Ambient storage losses were also lowest for carrots at 22.53% after 7 days, while tomato and cabbage losses stood at 24.27% and 34.34% after 3 days of storage, respectively. Vegetable firmness generally decreased while weight loss increased with storage time. Colour development increased favourably at ambient temperature for the tomato whereas for cabbage and carrot better colour retention was observed in the cold storage. Chemical changes for all three vegetables were also most pronounced at ambient temperature with significant (P<0.05) losses observed for ascorbic acid. Changes were also noted for total pigments, soluble solids and acidity, however there was no common significant trend for all three vegetables. Estimates of carbon dioxide emissions reveal that postharvest vegetable losses contribute to unwarranted emissions of at least 1.37 – 13.77 million tonnes of carbon dioxide equivalents (CO2eq.) at the national level. The losses are also accompanied by wastage of approximately 3.74 – 4.35 million m3 of fresh water as well as 14.79 – 111.63 million MJ of fossil energy. The vegetable with highest production volumes and retail price was the tomato and accordingly, its postharvest losses had the severest environmental and resource impacts.
AFRIKAANSE OPSOMMING: Die ná-oes-verliese van drie verskillende groentes (tamatie – 'n vrug, kool – 'n blaar, en wortel – 'n wortelgroente) is direk ná kleinhandelaankope en tydens gesimuleerde verbruikersberging ondersoek. Ten einde hierdie studie uit te voer, is drie kleinhandelsafsetpunte (twee supermarkte en 'n opelugmark) in Stellenbosch, Suid-Afrika gekies. Die kleinhandelpryse van elke groente van die drie onderskeie afsetpunte is opgeteken. Omliggende omgewingstoestande (lugtemperatuur en relatiewe humiditeit) tydens verkope en gesimuleerde verbruikersberging is ook gemonitor. Die ná-oes-verliese van die groentes is bepaal deur die voorkoms van fisiese verlies en veranderings in fisio-chemiese eienskappe (kleur, fermheid, gewigsverlies, askorbiensuur, totale pigmente, totale oplosbare suikers, titreerbare suur en algemene samestelling) met verloop van tyd te versyfer. Die waargenome persentasie verliese is gebruik om die geassosieerde ekonomiese en omgewingshulpbron-impak van ná-oes-groenteverliese op nasionale vlak te beraam. Groenteverliese met kleinhandelaankope was onderskeidelik 14.56%, 21.21% en 17.93% vir tamaties, kool en wortels. Die beraamde saamgestelde volume verlies vir al drie groentes op nasionale vlak was ongeveer 26 460 t, met 'n waarde van R33.70 miljoen. Die algehele ekonomiese verlies was die hoogste vir tamaties en die laagste vir wortels. Die omvang van die waargenome verliese het vir al die afsetpunte verskil. Groenteverliese tydens berging was hoofsaaklik hoog vir die produkte van die opelugmark in vergelyking met dié van die supermark. Tydens die algehele proefneming was meganiese skade verantwoordelik vir ten minste 50 tot 70% van die verliese, terwyl die res aan verrotting en insekskade toegeskryf kan word. Bergingstemperatuur ná kleinhandelaankope: omgewingstemperatuur (22 – 25 ºC) vs. koue berging (0 ºC en 10–12 ºC) het 'n beduidende (P < 0.05) uitwerking op groenteverlies gehad. Dit geld vir sowel kwantitatiewe as kwalitatiewe attribute. Verliese vir tamaties en kool was onderskeidelik 18.52% en 16.67% ná drie dae, terwyl dit vir wortels 11.83% teen sewe dae was nadat dit teen die aanbevole onderskeie koue bergingstemperature geberg is. Bergingsverliese in omgewingstemperatuur was ook die laagste vir wortels teen 22.53% ná sewe dae, terwyl die verlies van tamaties en kool onderskeidelik 24.27% en 34.34% was ná drie dae se berging. Die fermheid van die groente het oor die algemeen met die duur van berging verminder, terwyl gewigsverlies toegeneem het. Kleurontwikkeling het gunstig teen omgewingstemperatuur toegeneem vir die tamaties, terwyl die kleur van kool en wortels beter in die koue berging behou is. Chemiese veranderinge vir al drie groente was die sterkste teen omgewingstemperatuur, met beduidende (P < 0.05) verliese van askorbiensuur wat waargeneem is. Veranderinge is ook gemerk rakende totale pigmente, oplosbare vaste stowwe en suurgehalte. Daar was egter geen algemene beduidende neiging vir al drie groentes nie. Beramings van koolstofvrystellings toon dat ná-oes-groenteverlies tot ongeoorloofde vrystelling van ten minste 1.37 tot 13.77 miljoen ton koolstofekwivalente (CO2eq.) op nasionale vlak bydra. Die verliese gaan ook gepaard met verbruik van ongeveer 3.74 tot 4.35 miljoen m3 vars water asook 14.79 tot 111.63 miljoen MJ fossielbrandstof. Die groente met die hoogste produksievolume en kleinhandelprys was die tamaties, en gevolglik het tamaties se ná-oes-verliese die ernstigste impak op die omgewing en op hulpbronne.
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Valentyn, Aatika. "Orthodox and alternative strategies to control postharvest decay in table grapes." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/351.
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Santos, Jose Henrique dos. "Efeito do transporte manual na ocorrencia de danos mecanicos em banana (Musa cavendishii)." [s.n.], 1998. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257078.
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Orientador: Antonio Carlos de Oliveira FerrazDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
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Resumo: No Brasil, as perdas na colheita e pós-colheita estão estimadas em 30 a 40% da produção. As hortícolas são as espécies vegetais cultivadas economicamente que mais contribuem para a manutenção deste elevado índice de perdas. Dentre elas, destacam-se as frutas, e em especial a banana, com perdas totais estimadas em 40%. O conhecimento das propriedades mecânicas dos materiais biológicos contribui não só para o projeto e desenvolvimento de equipamentos de colheita e pós-colheita, como também para a melhor gestão da qualidade e vida útil dos produtos. Neste trabalho avaliou-se o efeito do transporte manual quanto aos danos produzidos nos frutos da bananeira ((Musa cavendishii), determinaram-se as áreas de contato entre ombro do carregador e frutos, mediram-se as acelerações produzidas nos frutos durante o transporte manual, para topografias plana, acidentada e em superfícies gramada e de concreto. Realizaram-se ensaios mecânicos de penetração, de compressão entre pratos planos e paralelos e ensaios cíclicos de compressão. Resultados evidenciaram a sensibilidade dos frutos aos danos mecânicos mesmo no estádio verde. Danos no pedúnculo não foram observados devido a ação do transporte. Observaram-se acelerações entre 0,15 a 1,35g (9,8ms-2) indicando cargas significativas de compressão, adicionais ao peso próprio, geradas durante o caminhamento. Compressões com cargas crescentes não produziram manchas de tamanhos correlacionados com a intensidade da carga revelando que o tamanho dos danos constitui bom indicador da severidade da solicitação mecânica. Os ensaios de compressão do fruto inteiro, entre prato planos e paralelos, revelaram escoamento biológico e diferentes níveis de resistência entre frutos localizados nas regiões superior, média e inferior do cacho. Os ensaios cíclicos de compressão revelaram que solicitações repetidas de pequenas amplitudes podem promover modificações permanentes no fruto com grande potencial de danos. De uma forma geral concluiu-se que danos mecânicos estão presentes no transporte manual e que soluções para proteção do cacho ou dispositivos de auxílio ao transporte sejam necessários para a redução desses danos
Abstract: Around 30% to 40% of total losses of agricultural production in Brazil occurs during harvesting and post harvesting processes. Fruits and vegetables are the major contributor to these high losses. Among them, banana can reach losses up to 40% of total production. The knowledge of mechanical properties of fruits and vegetables is important not only for better designing of handling equipment but also to improve quality management as well as shelf life. This work reports the development of a methodology to evaluate the mechanical damage of banana fruit during manual transportation. It was measured the contact area between shoulder and fruit, accelerations during manual transportation on irregular topography on grass and concrete surfaces. Mechanical tests of penetration, compression and cyclic compression between parallel rigid plates were also performed. Results brought into evidence the high sensitivity of green banana fruits to mechanical loads. Damages in the peduncle were not observed after manual transportation. Values of acceleration between 0,15 and 1,35 g (g=9,8ms-2) were measured indicating significant additional load to the weight of the bunch during transportation. Compressions using increasing loads did not produce bruise areas correlated to load values revealing that bruise area is not a good indicator of the magnitude of the applied load. Simple compression between flat plates reveled the presence of bio-yielding and different mechanical resistance in whole fruits grown in the upper, medium and lower part of the bunch. Cyclic compression showed that repeated loads of even of small amplitudes may promote permanent changes in mechanical behavior of the tissues with great possibility of damaging them. It was concluded that mechanical damages are present during manual transportation and solutions for protection of the bunch and development of transportation aids are desirable to reduce those damages
Mestrado
Maquinas Agricolas
Mestre em Engenharia Agrícola
Books on the topic "Postharvest losses"
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1949-, Chavan J. K., and Kadam S. S, eds. Postharvest biotechnology of cereals. Boca Raton, Fla: CRC Press, 1985.
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Bautista-Baños, Silvia. Postharvest decay: Control strategies. Amsterdam: Elsevier/AP, Academic Press is an imprint of Elsevier, 2014.
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Madagascar. Ministère de la production agricole et de la réforme agraire. Service de la méthodologie et du traitement des informations statistiques., Madagascar. Ministère de la production agricole et de la réforme agraire. Direction de la programmation., and Projet recensement national de l'agriculture et système permanent des statistiques agricoles (Madagascar), eds. Enquête sur les pertes de paddy après récolte. [Antanarivo]: Direction programmation, 1987.
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1941-, Desai B. B., ed. Postharvest biotechnology of sugar crops. Boca Raton, Fla: CRC Press, 1988.
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United Nations. Economic Commission for Africa. and United Nations. Economic Commission for Africa. Centre multinational de programmation et d'exécution des projets (Gisenyi, Rwanda). Intergovernmental Committee of Experts., eds. Survey on post-harvest food losses in the East Africa subregion. [Addis Ababa]: United Nations Economic Commission for Africa, 1997.
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Kanuma, Taremwa Nathan. Factors causing postharvest losses of maize in Rwanda: A case study of Ruhengeri and Kigali urban prefectures. Butare [Rwanda]: National University of Rwanda, Faculty of Agriculture, Department of Crop Sicence, 2000.
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Xing zheng yuan nong ye wei yuan hui (China), ed. Post-harvest prevention of paddy/rice loss. Taipei, R.O.C: Council of Agriculture, Executive Yuan, Republic of China, 1986.
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Food and Agriculture Organization of the United Nations., ed. Prevention of post-harvest food losses: A training manual. Rome: Food and Agriculture Organization of the United Nations, 1985.
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Wenham, J. E. Post-harvest deterioration of cassava: A biotechnology perspective. Rome: Food and Agriculture Organization of the United Nations, 1995.
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India. Directorate of Marketing and Inspection. and India. Dept. of Publication., eds. Marketable surplus and post-harvest losses of lentil in India, 2002. Delhi: Controller of Publications, Govt. of India, 2006.
Find full textBook chapters on the topic "Postharvest losses"
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Singh, Dinesh, Ram Roshan Sharma, and Amit Kumar Kesharwani. "Postharvest Losses of Horticultural Produce." In Postharvest Handling and Diseases of Horticultural Produce, 1–24. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003045502-1.
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Morgan, Lynette. "Harvest and postharvest factors." In Hydroponics and protected cultivation: a practical guide, 268–90. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789244830.0014.
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Abstract This chapter discusses harvest and postharvest factors. Harvesting involves the gathering or removal of a mature crop, with minimum damage and losses, from where it has been grown and transporting it on either for direct consumption or into the postharvest handling chain for further storage and distribution. Determination of harvest maturity, hand harvesting, robotic harvesting of greenhouse crops, postharvest handling, grading and storage, fresh-cut salad processing, shelf-life evaluation, packaging, postharvest cooling, postharvest handling damage, GAP - Good Agricultural practices in Postharvest Handling, postharvest storage, postharvest disorders, food safety and hygiene, ready-to-eat, minimally processed produce, certification and food safety systems, and postharvest developments are also discussed.
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Morgan, Lynette. "Harvest and postharvest factors." In Hydroponics and protected cultivation: a practical guide, 268–90. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789244830.0268.
Full textAbstract:
Abstract This chapter discusses harvest and postharvest factors. Harvesting involves the gathering or removal of a mature crop, with minimum damage and losses, from where it has been grown and transporting it on either for direct consumption or into the postharvest handling chain for further storage and distribution. Determination of harvest maturity, hand harvesting, robotic harvesting of greenhouse crops, postharvest handling, grading and storage, fresh-cut salad processing, shelf-life evaluation, packaging, postharvest cooling, postharvest handling damage, GAP - Good Agricultural practices in Postharvest Handling, postharvest storage, postharvest disorders, food safety and hygiene, ready-to-eat, minimally processed produce, certification and food safety systems, and postharvest developments are also discussed.
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Ramezanian, A., A. Amiri, and C. H. Crisosto. "Postharvest physiology and physiological disorders of fresh fig fruits." In The fig: botany, production and uses, 384–97. Wallingford: CABI, 2022. http://dx.doi.org/10.1079/9781789242881.0016.
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Abstract This chapter focuses on the high perishability of fresh fig fruits and their sensitivity to postharvest decay. The importance of cold storage along with postharvest treatments, such as modified atmosphere packaging, calcium treatment, SO2 fumigation, edible coating and other modern techniques, in the maintenance of fruit quality and reducing postharvest losses is also discussed.
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Mohammed, Majeed, and Lisa Kitinoja. "Capacity Building in Postharvest Loss Assessment, Postharvest Training, and Innovations for Reducing Losses." In Postharvest Extension and Capacity Building for the Developing World, 11–20. Boca Raton, Florida : CRC Press, [2019] | Series: World Food Preservation Center book series: CRC Press, 2018. http://dx.doi.org/10.1201/9781315115771-2.
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Shinde, Ranjeet, Victor Rodov, Shanthanu Krishnakumar, and Jayasankar Subramanian. "Active and Intelligent Packaging for Reducing Postharvest Losses of Fruits and Vegetables." In Postharvest Biology and Nanotechnology, 171–89. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2018. http://dx.doi.org/10.1002/9781119289470.ch7.
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Ejaz, Shaghef, Sajid Ali, Muhammad Azam, İhsan Canan, Laraib Amjad, and Fareeha Saeed. "Strategies to Reduce Postharvest Losses of Citrus Fruits." In Citrus Production, 391–404. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003119852-25.
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Chakraborty and Arup Chattopadhyay. "Pre- and Post-Harvest Losses in Vegetables IVI." In Advances in Postharvest Technologies of Vegetable Crops, 25–87. Waretown, NJ : Apple Academic Press, 2018. | Series: Postharvest biology and technology: Apple Academic Press, 2018. http://dx.doi.org/10.1201/9781315161020-2.
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Mwatawala, Maulid W., Anna Baltazari, Theodosy J. Msogoya, Hosea D. Mtui, Jaspa Samwel, and Lucy M. Chove. "Reduction of Preharvest and Postharvest Losses of Sweet Orange (Citrus sinensisL. Osberck) Using Hexanal in Eastern Tanzania." In Postharvest Biology and Nanotechnology, 255–64. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2018. http://dx.doi.org/10.1002/9781119289470.ch15.
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Khan, Ahmad Sattar, Sajid Ali, Raheel Anwar, and Rana Naveed Ur Rehman. "Preharvest Factors That Influence Postharvest Losses of Citrus Fruits." In Citrus Production, 319–43. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003119852-22.
Full textConference papers on the topic "Postharvest losses"
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Ng'ang'a, James. "Hermetic storage for controlling postharvest losses and aflatoxin poisoning." In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.105652.
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"Postharvest Losses due to Harvesting Operations in Developing Countries: A Review." In 2015 ASABE International Meeting. American Society of Agricultural and Biological Engineers, 2015. http://dx.doi.org/10.13031/aim.20152176663.
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Stevanović, Snežana. "Effect of storage in controlled atmosphere on apple fruits quality." In 35th International Congress on Process Industry. SMEITS, 2022. http://dx.doi.org/10.24094/ptk.022.055.
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Food market is increasingly interested in fresh, unprocessed food products containing no added chemicals. Increasing quantities of food are exported as fresh commodity; therefore, there is a demand for modern postharvest technologies. Fresh fruits continue with metabolic activities after harvest, resulting in continuous loss of fruit compounds, water and gaseous exchanges with surrounding environment through respiration and transpiration. This contributes significantly to postharvest quality loss because of resultant mass, firmness and freshness loss, as well as short shelf life which are the critical parameters determining the competitiveness of fresh produce in the market. One of the successful postharvest technologies used to reduce losses is the modification of the atmosphere, i.e. storage with a controlled atmosphere. The objective of this study was to evaluate the effect of storage in controlled atmosphere on quality changes of apple fruits. The regular air storage was used as a control. Soluble solids content, starch, pectin matter, total solid and acids, pH value and firmness were analyzed in fresh and stored apple fruits. The obtained results demonstrated significantly lower changes in analyzed quality parameters of apples stored in controlled atmosphere compared with air stored apples. After 4 months of storage in chamber under regular air, apples had significantly lower firmness than apples stored in controlled atmosphere. In addition, total loss was significantly higher in apples stored under regular air than in controlled atmosphere.
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"CURRENT MAIZE PRODUCTION, POSTHARVEST LOSSES AND THE RISK OF MYCOTOXINS CONTAMINATION IN TANZANIA." In 2015 ASABE International Meeting. American Society of Agricultural and Biological Engineers, 2015. http://dx.doi.org/10.13031/aim.20152189434.
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"Supply Chain Mapping and Postharvest Losses of Cabbage in Traditional and Modern Chains in Cebu, Philippines." In International Conference on Chemical, Environment & Biological Sciences. International Institute of Chemical, Biological & Environmental Engineering, 2014. http://dx.doi.org/10.15242/iicbe.c914092.
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Alam, Md Monjurul, Md Rostom Ali, Shibendra Narayan Gope, Md Abdul Awal, and Alex E. Winter-Nelson. "Hermetic Storage Technology to Reduce Postharvest Loss of Paddy: Farmers to Commercial Scale." In 2022 Houston, Texas July 17-20, 2022. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2022. http://dx.doi.org/10.13031/aim.202200252.
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Silvestri, Bartolomeo, Francesco Facchini, Salvatore Digiesi, and Luigi Ranieri. "A Framework of a Conceptual Model to manage the Food Lost and Waste in the Agri-Food supply chain." In The 8th International Food Operations and Processing Simulation Workshop. CAL-TEK srl, 2022. http://dx.doi.org/10.46354/i3m.2022.foodops.004.
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Food loss and waste (FLW) are significant opportunities for the agri-food sector. The FLW management includes all activities allowing to prevent, reduce, reuse, recycle, and recover the discarded food from the market during the postharvest supply chain. Although many strategies allow pursuing these actions, in most cases the availability of FLW generated in Primary Processing Centers does not meet the demand of stakeholders able to manage it. To increase the environmental, economic, and social benefits of FLW reuse, suitable strategies have to be adopted. Consistent with this aim, a conceptual model to be implemented in a business-to-business web platform is proposed to support the decision-maker in identifying the best FLW management strategy under a sustainable perspective, adopting a multicriteria decision method. The numerical simulation results proved the model's effectiveness in identifying the most appropriate FLW management strategy within a set of alternatives.
Reports on the topic "Postharvest losses"
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Ghafoor, Abdul, Md Abul Basher, Hammad Badar, and Sangjun Lee. Building Horticulture Value Chains and Reducing Postharvest Losses in Pakistan. Asian Development Bank, November 2022. http://dx.doi.org/10.22617/brf220545-2.
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This brief explains why weaknesses in Pakistan’s fruit and vegetable production sector are contributing to postharvest losses and outlines how stronger infrastructure and regulations can improve value chains and support development. It offers a comprehensive value chain analysis for products including apples, chilies, and potatoes, and explains the impact of factors such as inadequate storage, transport, packaging, and finance. It recommends that the government works with the private sector to develop modern agriculture markets, overhaul financing for growers, improve infrastructure and strengthen linkages throughout the value chain to cut losses and make the sector more sustainable.
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Lers, Amnon, Majid R. Foolad, and Haya Friedman. genetic basis for postharvest chilling tolerance in tomato fruit. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7600014.bard.
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ABSTRACT Postharvest losses of fresh produce are estimated globally to be around 30%. Reducing these losses is considered a major solution to ensure global food security. Storage at low temperatures is an efficient practice to prolong postharvest performance of crops with minimal negative impact on produce quality or human health and the environment. However, many fresh produce commodities are susceptible to chilling temperatures, and the application of cold storage is limited as it would cause physiological chilling injury (CI) leading to reduced produce quality. Further, the primary CI becomes a preferred site for pathogens leading to decay and massive produce losses. Thus, chilling sensitive crops should be stored at higher minimal temperatures, which curtails their marketing life and in some cases necessitates the use of other storage strategies. Development of new knowledge about the biological basis for chilling tolerance in fruits and vegetables should allow development of both new varieties more tolerant to cold, and more efficient postharvest storage treatments and storage conditions. In order to improve the agricultural performance of modern crop varieties, including tomato, there is great potential in introgression of marker-defined genomic regions from wild species onto the background of elite breeding lines. To exploit this potential for improving tomato fruit chilling tolerance during postharvest storage, we have used in this research a recombinant inbred line (RIL) population derived from a cross between the red-fruited tomato wild species SolanumpimpinellifoliumL. accession LA2093 and an advanced Solanum lycopersicumL. tomato breeding line NCEBR-1, developed in the laboratory of the US co-PI. The original specific objectives were: 1) Screening of RIL population resulting from the cross NCEBR1 X LA2093 for fruit chilling response during postharvest storage and estimation of its heritability; 2) Perform a transcriptopmic and bioinformatics analysis for the two parental lines following exposure to chilling storage. During the course of the project, we learned that we could measure greater differences in chilling responses among specific RILs compared to that observed between the two parental lines, and thus we decided not to perform transcriptomic analysis and instead invest our efforts more on characterization of the RILs. Performing the transcriptomic analysis for several RILs, which significantly differ in their chilling tolerance/sensitivity, at a later stage could result with more significant insights. The RIL population, (172 lines), was used in field experiment in which fruits were examined for chilling sensitivity by determining CI severity. Following the field experiments, including 4 harvest days and CI measurements, two extreme tails of the response distribution, each consisting of 11 RILs exhibiting either high sensitivity or tolerance to chilling stress, were identified and were further examined for chilling response in greenhouse experiments. Across the RILs, we found significant (P < 0.01) correlation between field and greenhouse grown plants in fruit CI. Two groups of 5 RILs, whose fruits exhibited reproducible chilling tolerant/sensitive phenotypes in both field and greenhouse experiments, were selected for further analyses. Numerous genetic, physiological, biochemical and molecular variations were investigated in response to postharvest chilling stress in the selected RILs. We confirmed the differential response of the parental lines of the RIL population to chilling stress, and examined the extent of variation in the RIL population in response to chilling treatment. We determined parameters which would be useful for further characterization of chilling response in the RIL population. These included chlorophyll fluorescence Fv/Fm, water loss, total non-enzymatic potential of antioxidant activity, ascorbate and proline content, and expression of LeCBF1 gene, known to be associated with cold acclimation. These parameters could be used in continuation studies for the identification and genetic mapping of loci contributing to chilling tolerance in this population, and identifying genetic markers associated with chilling tolerance in tomato. Once genetic markers associated with chilling tolerance are identified, the trait could be transferred to different genetic background via marker-assisted selection (MAS) and breeding. The collaborative research established in this program has resulted in new information and insights in this area of research and the collaboration will be continued to obtain further insights into the genetic, molecular biology and physiology of postharvest chilling tolerance in tomato fruit. The US Co-PI, developed the RIL population that was used for screening and measurement of the relevant chilling stress responses and conducted statistical analyses of the data. Because we were not able to grow the RIL population under field conditions in two successive generations, we could not estimate heritability of response to chilling temperatures. However, we plan to continue the research, grow the RIL progeny in the field again, and determine heritability of chilling tolerance in a near future. The IS and US investigators interacted regularly and plan to continue and expand on this study, since combing the expertise of the Co-PI in genetics and breeding with that of the PI in postharvest physiology and molecular biology will have great impact on this line of research, given the significant findings of this one-year feasibility project.
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Aghadi, Crystal N., Bedru Balana, and Adebayo Ogunniyi. Postharvest losses and the impact of reusable plastic container technology on profitability: Evidence from tomato traders in Nigeria. Washington, DC: International Food Policy Research Institute, 2020. http://dx.doi.org/10.2499/p15738coll2.134041.
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Lers, Amnon, and Gan Susheng. Study of the regulatory mechanism involved in dark-induced Postharvest leaf senescence. United States Department of Agriculture, January 2009. http://dx.doi.org/10.32747/2009.7591734.bard.
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Postharvest leaf senescence contributes to quality losses in flowers and leafy vegetables. The general goal of this research project was to investigate the regulatory mechanisms involved in dark-induced leaf senescence. The regulatory system involved in senescence induction and control is highly complex and possibly involves a network of senescence promoting pathways responsible for activation of the senescence-associated genes. Pathways involving different internal signals and environmental factors may have distinctive importance in different leaf senescence systems. Darkness is known to have a role in enhancement of postharvest leaf senescence and for getting an insight into its regulatory mechanism/s we have applied molecular genetics and functional genomics approaches. The original objectives were: 1. Identification of dark-induced SAGs in Arabidopsis using enhancer/promoter trap lines and microarray approaches; 2. Molecular and functional characterization of the identified genes by analyzing their expression and examining the phenotypes in related knockout mutant plants; 3. Initial studies of promoter sequences for selected early dark-induced SAGs. Since genomic studies of senescence, with emphasis on dark-induced senescence, were early-on published which included information on potential regulatory genes we decided to use this new information. This is instead of using the uncharacterized enhancer/promoter trap lines as originally planned. We have also focused on specific relevant genes identified in the two laboratories. Based on the available genomic analyses of leaf senescence 10 candidate genes hypothesized to have a regulatory role in dark-induced senescence were subjected to both expression as well as functional analyses. For most of these genes senescence-specific regulation was confirmed, however, functional analyses using knock-out mutants indicated no consequence to senescence progression. The transcription factor WARK75 was found to be specifically expressed during natural and dark-induced leaf senescence. Functional analysis demonstrated that in detached leaves senescence under darkness was significantly delayed while no phenotypic consequences could be observed on growth and development, including no effect on natural leaf senescence,. Thus, WARKY75 is suggested to have a role in dark-induced senescence, but not in natural senescence. Another regulatory gene identified to have a role in senescence is MKK9 encoding for a Mitogen-Activated Protein Kinase Kinase 9 which is upregulated during senescence in harvested leaves as well as in naturally senescing leaves. MKK9 can specifically phosphorylate another kinase, MPK6. Both knockouts of MKK9 and MPK6 displayed a significantly senescence delay in harvested leaves and possibly function as a phosphorelay that regulates senescence. To our knowledge, this is the first report that clearly demonstrates the involvement of a MAP kinase pathway in senescence. This research not only revealed a new signal transduction pathway, but more important provided significant insights into the regulatory mechanisms underlying senescence in harvested leaves. In an additional line of research we have employed the promoter of the senescence-induced BFN1 gene as a handle for identifying components of the regulatory mechanism. This gene was shown to be activated during darkinduced senescence of detached leaves, as well as natural senescence. This was shown by following protein accumulation and promoter activity which demonstrated that this promoter is activated during dark-induced senescence. Analysis of the promoter established that, at least some of the regulatory sequences reside in an 80 bps long fragment of the promoter. Overall, progress was made in identification of components with a role in dark-induced senescence in this project. Further studies should be done in order to better understand the function of these components and develop approaches for modulating the progress of senescence in crop plants for the benefit of agriculture.
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Prusky, Dov, Nancy P. Keller, and Amir Sherman. global regulation of mycotoxin accumulation during pathogenicity of Penicillium expansum in postharvest fruits. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7600012.bard.
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Background to the topic- Penicilliumas a postharvest pathogen and producer of the mycotoxin PAT. Penicilliumspp. are destructive phytopathogens, capable of causing decay in many deciduous fruits, during postharvest handling and storage; and the resulting losses can amount to 10% of the stored produce and the accumulation of large amounts of the mycotoxinpatulin. The overall goal of this proposal is to identify critical host and pathogen factors that modulate P. expansummycotoxin genes and pathways which are required for PAT production and virulence. Our preliminary results indicated that gluconic acid are strongly affecting patulin accumulation during colonization. P. expansumacidifies apple fruit tissue during colonization in part through secretion of gluconic acid (GLA). Several publications suggested that GLA accumulation is an essential factor in P. expansumpathogenicity. Furthermore, down regulation of GOX2 significantly reduced PAT accumulation and pathogenicity. PAT is a polyketide and its biosynthesis pathway includes a 15-gene cluster. LaeA is a global regulator of mycotoxin synthesis. It is now known that patulin synthesis might be subjected to LaeA and sometimes by environmental sensing global regulatory factors including the carbon catabolite repressor CreA as well as the pH regulator factor PacC and nitrogen regulator AreA. The mechanisms by which LaeA regulates patulin synthesis was not fully known and was part of our work. Furthermore, the regulatory system that controls gene expression in accordance with ambient pH was also included in our work. PacC protein is in an inactive conformation and is unable to bind to the promoter sites of the target genes; however, under alkaline growth conditions activated PacC acts as both an activator of alkaline-expressed genes and a repressor of acid-expressed genes. The aims of the project- This project aims to provide new insights on the roles of LaeA and PacC and their signaling pathways that lead to GLA and PAT biosynthesis and pathogenicity on the host. Specifically, our specific aims were: i) To elucidate the mechanism of pH-controlled regulation of GLA and PAT, and their contribution to pathogenesis of P. expansum. We are interested to understanding how pH and/or GLA impact/s under PacC regulation affect PAT production and pathogenesis. ii) To characterize the role of LaeA, the global regulator of mycotoxin production, and its effect on PAT and PacC activity. iii) To identify the signaling pathways leading to GLA and PAT synthesis. Using state- of-the-art RNAseq technologies, we will interrogate the transcriptomes of laeAand pacCmutants, to identify the common signaling pathways regulating synthesis of both GLA and PAT. Major conclusions, solutions, achievements- In our first Aim our results demonstrated that ammonia secreted at the leading edge of the fungal colony induced transcript activation of the global pH modulator PacC and PAT accumulation in the presence of GLA. We assessed these parameters by: (i) direct exogenous treatment of P. expansumgrowing on solid medium; (ii) direct exogenous treatment on colonized apple tissue; (iii) growth under self-ammonia production conditions with limited carbon; and (iv) analysis of the transcriptional response to ammonia of the PAT biosynthesis cluster. Ammonia induced PAT accumulation concurrently with the transcript activation of pacCand PAT biosynthesis cluster genes, indicating the regulatory effect of ammonia on pacCtranscript expression under acidic conditions. Transcriptomic analysis of pH regulated processes showed that important genes and BARD Report - Project 4773 Page 2 of 10 functionalities of P. expansumwere controlled by environmental pH. The differential expression patterns of genes belonging to the same gene family suggest that genes were selectively activated according to their optimal environmental conditions to enable the fungus to cope with varying conditions and to make optimal use of available enzymes. Concerning the second and third Aims, we demonstrated that LaeA regulates several secondary metabolite genes, including the PAT gene cluster and concomitant PAT synthesis invitro. Virulence studies of ΔlaeAmutants of two geographically distant P. expansumisolates (Pe-21 from Israel and Pe-T01 from China) showed differential reduction in disease severity in freshly harvested fruit ranging from no reduction for Ch-Pe-T01 strains in immature fruit to 15–25% reduction for both strains in mature fruit, with the ΔlaeAstrains of Is-Pe-21 always showing a greater loss in virulence. Results suggest the importance of LaeA regulation of PAT and other secondary metabolites on pathogenicity. Our work also characterized for the first time the role of sucrose, a key nutritional factor present in apple fruit, as a negative regulator of laeAexpression and consequent PAT production in vitro. This is the first report of sugar regulation of laeAexpression, suggesting that its expression may be subject to catabolite repression by CreA. Some, but not all of the 54 secondary metabolite backbone genes in the P. expansumgenome, including the PAT polyketide backbone gene, were found to be regulated by LaeA. Together, these findings enable for the first time a straight analysis of a host factor that potentially activates laeAand subsequent PAT synthesis.
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Yalch, Teale, Jo Lofthouse, and Stella Nordhagen. Creating alliances and fostering innovations to reduce postharvest food loss: Experiences from GAIN’s Postharvest Loss Alliances for Nutrition. Global Alliance for Improved Nutrition (GAIN), September 2020. http://dx.doi.org/10.36072/wp.9.
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Meir, Shimon, Michael S. Reid, Cai-Zhong Jiang, Amnon Lers, and Sonia Philosoph-Hadas. Molecular Studies of Postharvest Leaf and Flower Senescence. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7592657.bard.
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Original objectives: To understand the regulation of abscission by exploring the nature of changes of auxin-related gene expression in tomato (Lycopersicon esculatumMill) abscission zones (AZs) following organ removal, and by analyzing the function of these genes. Our specific goals were: 1) To complete the microarray analyses in tomato flower and leaf AZs, for identifying genes whose expression changes early in response to auxin depletion; 2) To examine, using virus-induced gene silencing (VIGS), the effect of silencing target genes on ethylene sensitivity and abscission competence of the leaf and flower AZs; 3) To isolate and characterize promoters from AZ-specific genes to be used in functional analysis; 4) To generate stable transgenic tomato plants with selected genes silenced with RNAi, under the control of an AZ-specific promoter, for further characterization of their abscission phenotypes. Background: Abscission, the separation of organs from the parent plant, results in postharvest quality loss in many ornamentals and other fresh produce. The process is initiated by changes in the auxin gradient across the AZ, and is triggered by ethylene. Although changes in gene expression have been correlated with the ethylene-mediated execution of abscission, there is almost no information on the initiation of the abscission process, as the AZ becomes sensitized to ethylene. The present project was focused on elucidating these early molecular regulatory events, in order to gain a better control of the abscission process for agricultural manipulations. Major conclusions, solutions, achievements: Microarray analyses, using the Affymetrix Tomato GeneChip®, revealed changes in expression, occurring early in abscission, of many genes with possible regulatory functions. These included a range of auxin- and ethylene-related transcription factors (TFs), other TFs that are transiently induced just after flower removal, and a set of novel AZ-specific genes. We also identified four different defense-related genes, including: Cysteine-type endopeptidase, α- DOX1, WIN2, and SDF2, that are newly-associated with the late stage of the abscission process. This supports the activation of different defense responses and strategies at the late abscission stages, which may enable efficient protection of the exposed tissue toward different environmental stresses. To facilitate functional studies we implemented an efficient VIGS system in tomato, and isolated two abscission-specific promoters (pTAPG1 and pTAPG4) for gene silencing in stable transformation. Using the VIGS system we could demonstrate the importance of TAPGs in abscission of tomato leaf petioles, and evaluated the importance of more than 45 genes in abscission. Among them we identified few critical genes involved in leaf and flower abscission. These included: PTRP-F1, PRP, TKN4, KNOTTED-like homeobox TF, KD1, and KNOX-like homeodomain protein genes, the silencing of which caused a striking retardation of pedicel abscission, and ERF1, ERF4, Clavata-like3 protein, Sucrose transporter protein, and IAA10 genes, the silencing of which delayed petiole abscission. The importance of PRPand KD1 genes in abscission was confirmed also by antisense–silencing using pTAPG4. Experiments testing the effects of RNAi silencing of few other genes are still in progress, The analysis of the microarray results of flower and leaf AZs allowed us to establish a clear sequence of events occurring during acquisition of tissue sensitivity to ethylene, and to confirm our hypothesis that acquisition of ethylene sensitivity in the AZ is associated with altered expression of auxin-regulated genes in both AZs. Implication, both scientific and agricultural: Our studies had provided new insights into the regulation of the abscission process, and shaded light on the molecular mechanisms that drive the acquisition of abscission competence in the AZ. We pointed out some critical genes involved in regulation of abscission, and further expanded our knowledge of auxin-ethylene cross talk during the abscission process. This permits the development of novel techniques for manipulating abscission, and thereby improving the postharvest performance of ornamentals and other crops.
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Fallik, Elazar, Robert Joly, Ilan Paran, and Matthew A. Jenks. Study of the Physiological, Molecular and Genetic Factors Associated with Postharvest Water Loss in Pepper Fruit. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7593392.bard.
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The fruit of pepper (Capsicum annuum) commonly wilts (or shrivels) during postharvest storage due to rapid water loss, a condition that greatly reduces its shelf life and market value. The fact that pepper fruit are hollow, and thus have limited water content, only exacerbates this problem in pepper. The collaborators on this project completed research whose findings provided new insight into the genetic, physiological, and biochemical basis for water loss from the fruits of pepper (Capsicum annuum and related Capsicum species). Well-defined genetic populations of pepper were used in this study, the first being a series of backcross F₁ and segregating F₂, F₃, and F₄ populations derived from two original parents selected for having dramatic differences in fruit water loss rate (very high and very low water loss). The secondly population utilized in these studies was a collection of 50 accessions representing world diversity in both species and cultivar types. We found that an unexpectedly large amount of variation was present in both fruit wax and cutin composition in these collections. In addition, our studies revealed significant correlations between the chemical composition of both the fruit cuticular waxes and cutin monomers with fruit water loss rate. Among the most significant were that high alkane content in fruit waxes conferred low fruit water loss rates and low permeability in fruit cuticles. In contrast, high amounts of terpenoids (plus steroidal compounds) were associated with very high fruit water loss and cuticle permeability. These results are consistent with our models that the simple straight chain alkanes pack closely together in the cuticle membrane and obstruct water diffusion, whereas lipids with more complex 3-dimensional structure (such as terpenoids) do not pack so closely, and thus increase the diffusion pathways. The backcross segregating populations were used to map quantitative trait loci (QTLs) associated with water loss (using DART markers, Diversity Arrays Technology LTD). These studies resulted in identification of two linked QTLs on pepper’s chromosome 10. Although the exact genetic or physiological basis for these QTLs function in water loss is unknown, the genotypic contribution in studies of near-isogenic lines selected from these backcross populations reveals a strong association between certain wax compounds, the free fatty acids and iso-alkanes. There was also a lesser association between the water loss QTLs with both fruit firmness and total soluble sugars. Results of these analyses have revealed especially strong genetic linkages between fruit water loss, cuticle composition, and two QTLs on chromosome 10. These findings lead us to further speculate that genes located at or near these QTLs have a strong influence on cuticle lipids that impact water loss rate (and possibly, whether directly or indirectly, other traits like fruit firmness and sugar content). The QTL markers identified in these studies will be valuable in the breeding programs of scientists seeking to select for low water loss, long lasting fruits, of pepper, and likely the fruits of related commodities. Further work with these newly developed genetic resources should ultimately lead to the discovery of the genes controlling these fruit characteristics, allowing for the use of transgenic breeding approaches toward the improvement of fruit postharvest shelf life.
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Lers, Amnon, E. Lomaniec, S. Burd, A. Khalchitski, L. Canetti, and Pamela J. Green. Analysis of Senescence Inducible Ribonuclease in Tomato: Gene Regulation and Function. United States Department of Agriculture, February 2000. http://dx.doi.org/10.32747/2000.7570563.bard.
Full textAbstract:
Natural leaf senescence has a negative influence on yield. Postharvest induced senescence contributes to the losses of quality in flowers, foliage, and vegetables. Strategies designed to control the senescence process in crop plants could therefore have great applied significance. Senescence is regulated by differential gene expression yet, functional characterization of the genes specifically induced and study of their expression control, is still in its infancy. Study of senescence-specific genes is required to allow identification of regulatory elements participating in senescence-induced expression and thus provide insights into the genetic regulation of senescence. A main feature of senescence is the hydrolysis of macromolecules by hydrolases of various types such as RNases and proteases. This study was aimed a analysis of senescence-inducible RNases in tomato with the following objectives: Isolation of senescence-inducible RNase cDNA clones; Expression analyses of RNase genes during senescence; Identification of sequences required for senescence-induced gene expression; Functional analyses of senescence-inducible RNases. We narrowed our aims somewhat to focus on the first three objectives because the budget we were awarded was reduced from that requested. We have expanded our research for identification senescence-related RNase/nuclease activities as we thought it will direct us to new RNase/nuclease genes. We have also carried out research in Arabidopsis and parsley, which enabled us to draw mire general conclusions. We completed the first and second objectives and have made considerable progress on the remaining two. We have defined growth conditions suitable for this research and defined the physiological and biochemical parameters characteristic to the advance of leaf senescence. In tomato and arabidopsis we have focused on natural leaf senescence. Parsley was used mainly for study of postharvest senescence in detached leaves. We have identified a 41-kD a tomato nuclease, LeNUCI, specifically induced during senescence which can degrade both RNA and DNA. This activity could be induced by ethylene in young leaves and was subjected to detailed analysis, which enabled its classification as Nuclease I enzyme. LeNUCI may be involved in nucleic acid metabolism during tomato leaf senescence. In parsley senescing leaves we identified 2 main senescence-related nuclease activities of 41 and 39-kDa. These activities were induced in both naturally or artificially senescing leaves, could degrade both DNA and RNA and were very similar in their characteristics to the LeNUCI. Two senescence-induced RNase cDNAs were cloned from tomato. One RNase cDNA was identical to the tomato LX RNase while the second corresponded to the LE RNase. Both were demonstrated before to be induced following phosphate starvation of tomato cell culture but nothing was known about their expression or function in plants. LX gene expression was much more senescence specific and ethylene could activate it in detached young leaves. LE gene expression, which could be transiently induced by wounding, appeared to be activated by abscisic acid. We suggest that the LX RNase has a role in RNA catabolism in the final stage of senescence, and LE may be a defense-related protein. Transgenic plants were generated for altering LX gene expression. No major visible alterations in the phenotype were observed so far. Detailed analysis of senescence in these plants is performed currently. The LX promoter was cloned and its analysis is performed currently for identification of senescence-specific regulatory elements. In Arabidopsis we have identified and characterized a senescence-associated nuclease 1 gene, BFN1, which is highly expressed during leaf and stem senescence. BFN1, is the first example of a senescence- associated gene encoding a nuclease I enzyme as well as the first nuclease I cloned and characterized from Arabidopsis. Our progress should provide excellent tools for the continued analysis of regulation and function of senescence-inducible ribonucleases and nucleases in plants. The cloned genes can be used in reverse genetic approaches, already initiated, which can yield a more direct evidence for the function of these enzymes. Another contribution of this research will be in respect to the molecular mechanism, which controls senescence. We had already initiated in this project and will continue to identify and characterize regulatory elements involved in senescence-specific expression of the genes isolated in this work.
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Lers, Amnon, and Pamela J. Green. LX Senescence-Induced Ribonuclease in Tomato: Function and Regulation. United States Department of Agriculture, September 2003. http://dx.doi.org/10.32747/2003.7586455.bard.
Full textAbstract:
Natural leaf senescence, which occurs even when growth conditions are near optimal, has a negative influence on yield. Postharvest induced senescence contributes to the losses of quality in flowers, foliage, and vegetables. Strategies designed to control the senescence process in crop plants could therefore have great applied significance. However, the successful design of such strategies requires a better insight into the senescence machinery and control in higher plants. A main feature of senescence is the hydrolysis of macromolecules by hydrolases of various types such as ribonucleases (RNases) and proteases. Previously we had identified and characterized the tomato LX RNase gene demonstrating its transcript to be highly and specifically induced during senescence. This reported study was focused on LX but also had broadened our research to other senescence-associated nucleic acids degrading enzymes to learn about their function and the regulation of their encoding genes. Beside tomato we used parsley and Arabidopsis for the study of: the bi-functional nuclease which has a role in senescence. The study of different senescence- associated nucleases in few plant systems will allow a more general view on function and regulation of these enzymes in senescence. The specific original proposed objectives included: 1. Study the consequences of alterations in LX RNase level on tomato leaf senescence and general development; 2. Analyze stimuli which may participate in senescence-specific activation of the LX gene; 3. Clone the senescence-associated BFNI nuclease gene homologue from tomato. 4. Further characterize the sequences required for senescence-specific gene expression. Homozygous transgenic plants in which LX gene was either inhibited or over-expressed were generated. In both of these LX mutated plants no major phenotypic consequences were observed, which may suggests that LX is not essential for plant growth under optimal growth conditions. Lack of any abnormalities in the LX over-expressing lines suggests that special system exist to allow function of the RNase only when needed. Detailed analyses of growth under stress and consequences to RNA metabolism are underway. We have analyzed LX expression on the protein level demonstrating that it is involved also in petal senescing. Our results suggest that LX is responding to complex regulation involving developmental, organ dependent factors and responds differently to hormonal or environmental stimuli in the different plant organs. The cloned 1.4 kb promoter was cloned and its analysis revealed that probably not all required elements for senescence induction are included. Biochemical analysis of senescence-associated be-functional nucleases in the different plants, tomato, parsley and Arabidopsis, suggests they belong to a sub-class within the type I plant nucleases. The parsley PcNUC1/2 nuclease protein was purified from senescing leaves its and activity was studied in vitro revealing endo-, double strand, nucleolytic activity and exo-nucleolytic activity. Its encoding gene was cloned and found to be induced on the mRNA level. The promoter of the related Arabidopsis BFNI nuclease was shown in both tomato and Arabidopsis to be able and direct senescence-specific expression suggesting that, at least part, the gene is regulated on the transcriptional level and that the mechanism for this senescence-specific regulation is conserved between different plants. Few plants in which the BFNI gene is mutated were identified which are subjected now to detailed analysis. Our results suggest that the senescence-related nucleic acid degrading enzymes share similarities in both function and regulation between different plants and possibly have important functions in processes un-related to senescence. Still, the function of these enzymes, at least in some cases is not essential to plant development under optimal growth conditions. We are now at the stage which permits in depth investigation of the specific functions and mode of molecular regulation of senescence-associated nucleases with the aid of the research tools developed. The isolated senescence-specific promoter, shown to be active in heterologous plant system, could be utilized in agricultural-related biotechnological applications for retardation of senescence.