Academic literature on the topic 'Mill yield'

Thesis (MScAgric)--Stellenbosch University, 2011.<br>ENGLISH ABSTRACT: The potential importance of soilless production, particularly in tomatoes, in an increasingly water scarce South Africa prompts a need for research under local conditions. In soilless production systems the application and availability of nutrients is closely linked to that of water, necessitating the research of methods to increase water and fertiliser use efficiency in soilless production systems, while diminishing environmental pollution and maintaining, or ultimately improving, tomato yield and quality. Poor management of hydroponic fertigation water results in pollution, and wastes precious water and expensive fertiliser. Pruning is an important cultural practise for ensuring high productivity of hydroponic tomatoes. Adapting pruning practises to climatic conditions could be a cheap and effective manner to improve productivity without increasing inputs. Improving water and fertiliser use efficiency is crucial to ensuring sustainable production of intensive crops, such as the tomato. Three experiments were carried out to investigate the effects of pruning and fertilisation on growth and yield and water and fertiliser use efficiency of hydroponic tomatoes. In the first experiment the effect of EC (electrical conductivity), irrigation frequency and growing media on water use, nutrient uptake, yield and quality of greenhouse tomato was examined. A factorial design with split plots was used. Two EC treatments (1 and 2 mS.cm-1) in factorial arrangement with 3 irrigation treatments (5x, 10x, 20x) were applied to the main plots. Plants grown in different growing media (coir, sand, sawdust) represented the split plots. Plants grown at EC 1 mS.cm-1 were still able to uptake sufficient nutrients to achieve leaf nutrient contents associated with optimal production. Also, increasing the absolute nutrient concentration had a small effect on nutrient uptake. The organic media, coir and sawdust, reduced available N early in the tomato crop life, and tomatoes grown in coir had reduced Ca uptake compared to plants grown in sand and sawdust. Coir grown plants used more water compared to sand and sawdust grown plants. Plants grown at EC 1 mS.cm-1 used less water compared to plants grown at EC 2 mS.cm-1. Tomatoes grown at an EC 1 mS.cm-1 did not differ significantly from higher EC plants in terms of marketable and green fruit yield. Plants cultivated at the lower EC had significantly lower percentage soluble solids content (Brix) compared to the higher EC treatment. The second experiment examined the effect of leaf and fruit pruning on fruit size, total yield and marketable yield of tomatoes. Plants were grown using the high wire system and pruned to two stems. Three different leaf pruning treatments were applied: no leaf pruning, pruning every 2nd young leaf after 1m plant height, and pruning every 2nd young leaf after 2m plant height. Two fruit pruning treatments were also applied: no fruit pruning and trusses pruned to 4 fruits. The experiment used a factorial design. Leaf pruning treatments had no effect and this was probably due to too late a removal of young leaves. Fruit pruning resulted in no significant difference between treatments in terms of marketable yield. Plants with unpruned trusses did have a significantly higher total yield, higher early yield, lower average marketable fruit weight, and higher yield of unmarketable fruit (particularly small fruit compared to the pruned treatment). From these results it can be concluded that fruit pruning isn’t necessary on short tomato crops but this may be different over a longer cropping cycle. The third experiment determined the combined effects of different EC and stem pruning practices on nutrition, growth and early yield of hydroponically grown tomatoes in coir. A factorial design was used, with two EC treatments (1 and 2 mS.cm-1) in factorial arrangement with 2 stem pruning treatments (single and double). Stem pruning had little effect on plant growth but did alter plant development. Plants pruned to two stems produced significantly more trusses, but did not produce a significantly higher DM or leaf area compared to single stem plants. Stem pruning’s major effect appears to be influencing fruit load; this may in the long term result in differences in plant growth and nutrition. EC 1 mS.cm-1 plants produced significantly lower leaf area and organ dry masses but had a significantly higher marketable yield compared to EC 2 mS.cm-1 plants. Over fertilisation in young tomatoes can negatively impact on early yield, whereas lower fertiliser application in early tomato growth improves early yield but limits canopy development which may limit plant productivity in the long term. These differences in growth are believed to be primarily related to differences in N and P nutrition.<br>AFRIKAANSE OPSOMMING: Die potensiële belang van grondlose produksietegnieke, veral by tamaties, in Suid-Afrika wat toenemend meer water skaars raak, motiveer dat navorsing onder plaaslike toestande gedoen moet word. By grondlose produksie stelsels word die toediening en die beskikbaarheid van voedingstowwe nou gekoppel aan dié van water. Navorsing rakende metodes wat water en kunsmis gebruiks doeltreffendheid sal verhoog en terselfdertyd besoedeling van die omgewing voorkom asook die opbrengste en kwaliteit van tamaties behou of verbeter is dus van uiterste belang. Swak bestuur van bemesting in hidroponiese stelsels gee aanleiding tot water besoedeling en vermorsing van kosbare water en duur kunsmis. Snoei is 'n belangrike kulturele praktyk om hoë produktiwiteit by hidroponiese tamaties te verseker. Die aanpassing van snoei praktyke by klimaatstoestande is 'n goedkoop en doeltreffende manier om produktiwiteit te verbeter sonder om insette te verhoog. Die verbetering van water en kunsmis gebruiks doeltreffendheid is dus noodsaaklik om te verseker dat intensiewe gewasse, soos tamaties, volhoubaar geproduseer word. Drie eksperimente is uitgevoer om die effek van snoei en bemesting op die groei, opbrengs en water en kunsmis gebruiks doeltreffendheid van hidroponiese tamaties te ondersoek. In die eerste eksperiment is die effek van die EG, besproeiings frekwensie en groeimedium op die water gebruik, voedingstofopname, opbrengs en kwaliteit van tamaties ondersoek. 'n Faktoriaal ontwerp met gesplete plotte is gebruik. Twee EG behandelings (1 en 2 mS.cm-1), 3 besproeiings behandelings (5x, 10x, 20x per dag) en 3 groei media (kokos, sand, saagsels) is ondersoek. Selfs by ‘n EG van 1 mS.cm-1 was die voedingstof opname van plante vergelykbaar met waardes wat geassosieer word met blaar ‘n voedingstof inhoud wat voorgeskryf vir optimale produksie. die verhoging van die absolute voedingstof konsentrasie het ook 'n klein uitwerking op voedingstofopname gehad. In die organiese media - kokos en saagsels – het die beskikbare N vroeg in die seisoen verminder, en die tamaties wat in kokos gegroei het, het ook ‘n verminderde Ca opname getoon in vergelyking met die plante wat in sand en saagsels gegroei het. Die plate wat in kokos gegroei het, het meer water gebruik in vergelyking met plante wat in sand en saagsels gegroei het. Plante besproei met ‘n voedingsoplossing van 1 mS.cm-1 EG het minder water gebruik as die plante wat besproei met ‘n voedingsolossing by ‘n EG van 2 mS.cm-1. Tamaties wat gekweek word by 'n EG van 1 mS.cm-1 het nie beduidend verskil van hoër EG plante in terme van bemarkbare en groen vrugte nie. Plante wat gekweek is by die laer EG het ‘n aansienlike laer persentasie oplosbare vastestof inhoud (Brix) in vergelyking met die hoër EG-behandeling gehad. Die tweede eksperiment het die effek van blaar- en vrug snoei op die vruggrootte, totale opbrengs en bemarkbare opbrengs van tamaties ondersoek. Plante is vertikaal opgelei tot by die horisontale draad en na twee stamme gesnoei. Drie verskillende blaar snoei behandelings is toegepas: geen blaar snoei, snoei elke 2de jong blaar na 1m plant hoogte en snoei van elke 2de jong blaar na 2m plant hoogte. Twee vrug snoei behandelings is ook toegepas: geen vrugte gesnoei en trosse gesnoei tot 4 vrugte. ‘n Faktoriale ontwerp is vir hierdie eksperiment gebruik. Blaar snoei behandelings het geen effek gehad nie, waarskynlik omdat die jong blare te laat verwyder was. Met die vrug snoei behandelings was daar geen beduidende verskil tussen die behandelings in terme van bemarkbare opbrengs nie. Plante waarvan die trosse nie gesnoei was nie het 'n aansienlik hoër totale opbrengs gelewer, asook ‘n hoër vroeë opbrengs maar ‘n laer gemiddelde bemarkbare vrug massa en ‘n hoër persentasie onbemarkbare vrugte (baie klein vrugte in vergelyking met die gesnoeide behandeling). Vanuit hierdie resultate kan daar afgelei word dat vrug snoei nie nodig is tydens ‘n kort groeiperiode vir tamaties nie, alhoewel dit wel ‘n rol mag speel gedurende ‘n langer groeiperiode. Met die derde eksperiment is die gekombineerde effek van verskillende EG en stam snoei praktyke op voeding, groei en vroeë opbrengs van hidroponies verboude tamaties bepaal. 'n faktoriale ontwerp is gebruik, met twee EG behandelings (1 en 2 mS.cm-1) en 2 stam snoei behandelings (enkel en dubbel). Stam snoei het ‘n geringe uitwerking op die groei van die plant gehad, maar het wel die ontwikkeling van plante verander. Plante gesnoei na twee stamme het aansienlik meer trosse gehad, maar nie 'n hoër DM of blaar oppervlak as die enkele stam plante nie. Stam snoei se grootste effek blyk te wees op die aantal vrugte per plant en dit kan op die lang termyn lei tot verskille in die groei van plante en hul voeding. EG 1 mS.cm-1 plante het ‘n aansienlik laer blaaroppervlakte en droë massas geproduseer, maar het 'n aansienlik hoër bemarkbare opbrengs in vergelyking met EG 2 mS.cm-1 plante gelewer. Oorbemesting kan 'n negatiewe impak op die vroeë opbrengste van tamaties hê, terwyl laer bemesting in die vroeë stadiums van groei vroeë opbrengs bevoordeel maar blaaroppervlak ontwikkeling beperk wat dan ook produktiwiteit beperk in die lang termyn. Hierdie verskille in groei word hoofsaaklik toegeskryf aan verskille in die N-en P-voeding.

Dissertation (PhD)--Stellenbosch University, 2004.<br>ENGLISH ABSTRACT: Pine sawdust-shavings (Pinus spp.) is at present a very popular soilless substrate in South African greenhouses. Growers use fresh pine sawdust-shavings as a substrate, which is biologically highly unstable. The greenhouse industry is looking at alternative organic substrates such as coco peat, which already went through a decomposition process and is more stable. A biological inactive substrate such as sand was included to compare microorganism activity with organic substrates. The main objective of this study was to compare the growth, yield and quality of hydroponically grown tomatoes in response to different growth mediums in combination with nitrogen source, irrigation frequency, period of substrate use and liming. In general the drainage water pH declined with an increase in NlLt+-N in the nutrient solution. Low pH values in the drainage water, especially when coco peat was used, had a detrimental effect on marketable yield. The drainage water pH of pine sawdustshavings increased during the growing season when 100 % N03--N was used. Due to the higher cation exchange capacity of coco peat, the drainage water electrical conductivity tends to increase more rapidly than with pine sawdust-shavings, during conditions with high temperatures and when insufficient irrigation volumes per irrigation cycle is applied. As expected the drainage water N03--N content decreased as the NlLt+-N content increased in the nutrient solution. Pine sawdust-shavings recorded a much lower N03--N and NlLt+-N content than sand and coco peat and thus supports the hypothesis that microbiological activity is higher in pine sawdustshavings, especially in the second season of substrate use. Coco peat produced the highest number of marketable fruit and yield per plant, followed by pine sawdustshavings and sand in the first season of substrate use. The number of marketable fruit and yield decreased with an increase in NlLt+-N content in the nutrient solution during production in warmer, summer conditions. Contrary to these fmdings, production in cooler, winter conditions recorded high yields when only N03--N or 80% N03--N : 20% NRt +-N was applied. The unmarketable yield increased with an increase in NlLt+-N in the nutrient solution. Visual evaluations showed that blossom-end rot (BER) was the main contributor to unmarketable yield. Increasing levels ofN03--N as nitrogen source in the nutrient solution, reduced weight loss and increased the loss of fruit firmness of tomatoes during storage. Increasing levels of N03 --N also increased fruit pH and reduced total titratable acidity. Coco peat produced fruit with a higher pH than pine sawdust-shavings. An increase in irrigation frequency affected fruit firmness negatively when coco peat was used as substrate. Different irrigation and fertigation practices are needed for different growth mediums and management needs to be adapted according to the growing season (winter vs. summer).<br>AFRIKAANSE OPSOMMING: 'n Mengsel van dennesaagsels en -skaafsels (Pinus spp.) word tans deur Suid- Afrikaanse kweekbuisprodusente gebruik as grondlose groeimedium. Hierdie groeimedium word nie vooraf gekomposteer nie en is dus biologies onstabiel. Die kweekbuisindustrie ondersoek tans die gebruik van alternatiewe, gekomposteerde en stabiele organiese groeimediums soos kokosveen. 'n Biologies onaktiewe groeimedium soos sand is ook ingesluit om met organiese groeimediums te kan vergelyk. Die hoof doelwit van die studie was om plantontwikkeling, opbrengs en kwaliteit van hidroponies geproduseerde tamaties te evalueer in verskillende groeimediums en in kombinasie met stikstofbron-verhouding, periode van groeimedium gebruik, besproeiingsfrekwensie en bekalking. Oor die algemeen het die pH in die dreinaat gedurende die groeiseisoen toegeneem soos die NH/-N inhoud verhoog het in die voedingsoplossing. Lae pH waardes in die dreinaat, veral waar kokosveen gebruik was, het 'n nadelige effek op bemarkbare opbrengs gehad. Die pH in die dreinaat van dennesaagsels en -skaafsels het gedurende die groeiseisoen toegeneem met die gebruik van 100% NO)--N in die voedingsoplossing. Die elektriese geleiding in die dreinaat van kokosveen neem vinniger toe gedurende toestande waarin hoë temperature en onder besproeiing voorkom, as in dreinaat van dennesaagsels en -skaafsels. Die NO)--N inhoud in die dreinaat het soos verwag afgeneem soos die NRt+-N inhoud in die voedingsoplossing toegeneem het. 'n Baie laer NO)--N en NRt+-N inhoud is by dennesaagsels en -skaafsels aangeteken wat dus die hipotese ondersteun dat mikrobiologiese aktiwiteit, veral in die tweede seisoen van gebruik, hoër is in dennesaagsels en -skaafsels as in sand en kokosveen. Kokosveen het die hoogste aantal bemarkbare vrugte en massa per plant geproduseer, gevolg deur dennesaagsels en -skaafsels en sand. Die aantal bemarkbare vrugte en opbrengs het verlaag met 'n verhoging in NRt+-N in die voedingsoplossing gedurende warm, somer toestande. In teenstelling met vorige resultate is gevind dat 100% NO)-- N of 80% NO)--N : 20% NRt+-N hoë opbrengste gelewer het gedurende koeler, winter toestande. Die onbemarkbare opbrengs het verhoog met hoër NRt+-N vlakke. Visuele waarnemings het aangedui dat blom-end verrotting die grootste bydrae tot onbemarkbare opbrengs gelewer het. 'n Verhoging in NO)--N vlakke het massaverlies beperk en die verlies in fermheid verhoog gedurende opberging. Hoër NO)--N vlakke het ook die pH van vrugte verhoog en die totale titreerbare suur verlaag. Kokosveen het vrugte met 'n hoër pH as dennesaagsels en -skaafsels geproduseer. 'n Toename in besproeiingsfrekwensie het vrug fermheid negatief beïnvloed wanneer kokosveen as groeimedium gebruik was. Verskillende besproeiings- en voedingspraktyke word benodig vir verskillende groeimediums en bestuur van die groeimediums moet aangepas word by klimaatstoestande gedurende die spesifieke produksieseisoen.

This study examined the potential for improvement within a conventional (crosscut-first) rough mill. Improvement was measured in terms of volume and also value of cuttings produced. Current levels of yield were obtained from an in-plant yield study of 138 boards. The same material was then processed with a computer optimization program designed to simulate a crosscut-first operation. Tests between the two methods, actual and optimized, showed that . current levels of cutting volume production were not able to be improved upon with optimization. Due to the varying costs of different length cuttings, however, a significant increase in the value of cuttings produced was possible. The distribution of cutting lengths produced was found to be a signficant factor in these results.<br>Master of Science<br>incomplete_metadata

Nitrogen is required by plants in large quantities and its deficiency is mostly related to reduction in crop production. A study was conducted to assess the importance of nitrogen in tomato (Lycopersicon esculentum Mill.) transplant production. Transplants were propagated at 0, 30, 60, 90, and 120 mg∙L-1 N applied as NH4NO3 while 30 mg∙L-1 P applied as NaH2PO4 and 30 mg∙L-1 K as KCl were used. Fergitation was done by floating cavity trays in nutrient solution until the medium reached field capacity. The experiment was arranged in a randomized complete block design (RCBD) with four replications. Sampling was initiated at 21 days after sowing and was done weekly until the transplants were ready for transplanting (when transplants could be pulled out of the cavity easily without breaking) at 42 days after sowing. Nitrogen supply had a pronounce influence on the transplant root and shoot growth. Observations throughout the experiment indicated that increased nitrogen application favoured shoot growth which is an indication that most of the assimilates were partitioned to shoots rather than to roots. Nitrogen application of 120 mg∙L-1increased fresh shoot mass and subsequently enhanced dry shoot mass. As nitrogen was increased from 0 to 120 mg∙L-1, it further promoted relative growth rate, specific leaf area, leaf mass ratio, leaf area ratio, plant chlorophyll content, leaf tissue nitrogen and improved the pulling success. At 42 days after sowing, a quality transplant that was produced with 90 mg∙L-1 N, had a root to shoot ratio of 0.16, leaf mass ratio of 0.86, root mass ratio of 0.13, leaf area of 594 cm2, plant chlorophyll content of 33, leaf tissue nitrogen of 32 g∙kg-1, specific leaf area of 194 cm2∙mg-1, leaf area ratio of 167.7 cm2∙mg-1, relative growth ratio of 0.31 cm∙mg-1∙wk-1 and 100% pulling success. This transplant proved to be ideal for the production of tomato as compared to other treatment combinations that were employed. Another glasshouse experiment was conducted to determine the influence of electrical conductivity (EC) and or nutrient solution composition on growth, yield and quality parameters in tomato. The pots were arranged in a randomized complete block design (RCBD). One plant per pot represented an experimental unit. Four EC treatments were used that consisted of 1.12, 2.24, 4.48 and 6.72 mS∙cm-1. Each treatment was replicated six times. Distilled water was used for irrigation water to maintain the required pH, which was 5.5 to 6.2 throughout the duration of the study, and cocopeat was used as substrate. Salinity inhibited growth (shoot length) and yield (average fruit mass, fruit diameter and fruit circumference) at the highest concentration of 6.72 mS∙cm-1. However, it did not significantly affect number of trusses, number of fruits and stem diameter, rather tomato quality was improved in terms of total soluble solids. Although tomato fruits grown at 6.72 mS∙cm-1 were relatively smaller than fruits grown at 1.12, 2.24 and 4.48 mS∙cm-1 treatments respectively, they had higher acidity, increased soluble solids and higher sugar content which are all qualities required by the tomato processing industry. Increasing the concentration of the solution from 1.12 to 6.72 mS∙cm-1 increased the %Brix from 3.9 to 6.1% while titratable acidity was also increased from 3.3 to 5.7%, respectively. The incidents of blossom end rot were higher (6.3%) at concentration of 6.72 mS∙cm-1 as compared to 1.12 mS∙cm-1 concentration, which was 0.5%.<br>Dissertation (MScAgric)--University of Pretoria, 2014.<br>tm2015<br>Plant Production and Soil Science<br>MScAgric<br>Unrestricted

Secondary hardwood products manufacturers have been placing heavy emphasis on lumber yield improvements in recent years. More attention has been on lumber grade and cutting technology rather than cutting bill design. However, understanding the underlying physical phenomena of cutting bill requirements and yield is essential to improve lumber yield in rough mills. This understanding could also be helpful in constructing a novel lumber yield estimation model. The purpose of this study was to advance the understanding of the phenomena relating cutting bill requirements and yield. The scientific knowledge gained was used to describe and quantify the effect of part length, width, and quantity on yield. Based on this knowledge, a statistics based approach to the lumber yield estimation problem was undertaken. Rip-first rough mill simulation techniques and statistical methods were used to attain the study's goals. To facilitate the statistical analysis of the relationship of cutting bill requirements and lumber yield, a theoretical concept, called cutting bill part groups, was developed. Part groups are a standardized way to describe cutting bill requirements. All parts required by a cutting bill are clustered within 20 individual groups according to their size. Each group's midpoint is the representative part size for all parts falling within an individual group. These groups are made such that the error from clustering is minimized. This concept allowed a decrease in the number of possible factors to account for in the analysis of the cutting bill requirements - lumber yield relationship. Validation of the concept revealed that the average error due to clustering parts is 1.82 percent absolute yield. An orthogonal, 220-11 fractional factorial design of resolution V was then used to determine the contribution of different part sizes to lumber yield. All 20 part sizes and 113 of a total of 190 unique secondary interactions were found to be significant (a = 0.05) in explaining the variability in yield observed. Parameter estimates of the part sizes and the secondary interactions were then used to specify the average yield contribution of each variable. Parts with size 17.50 inches in length and 2.50 inches in width were found to contribute the most to higher yield. The positive effect on yield due to parts smaller than 17.50 by 2.50 inches is less pronounced because their quantity is relatively small in an average cutting bill. Parts with size 72.50 by 4.25 inches, on the other hand, had the most negative influence on high yield. However, as further analysis showed, not only the individual parts required by a cutting bill, but also their interaction determines yield. By adding a sufficiently large number of smaller parts to a cutting bill that requires large parts to be cut, high levels of yield can be achieved. A novel yield estimation model using linear least squares techniques was derived based on the data from the fractional factorial design. This model estimates expected yield based on part quantities required by a standardized cutting bill. The final model contained all 20 part groups and their 190 unique secondary interactions. The adjusted R2 for this model was found to be 0.94. The model estimated 450 of the 512 standardized cutting bills used for its derivation to within one percent absolute yield. Standardized cutting bills, whose yield level differs by more than two percent can thus be classified correctly in 88 percent of the cases. Standardized cutting bills whose part quantities were tested beyond the established framework, i.e. the settings used for the data derivation, were estimated with an average error of 2.19 percent absolute yield. Despite the error observed, the model ranked the cutting bills as to their yield level quite accurately. However, cutting bills from actual rough mill operations, which were well beyond the framework of the model, were found to have an average estimation error of 7.62 percent. Nonetheless, the model classified four out of five cutting bills correctly as to their ranking of the yield level achieved. The least squares estimation model thus is a helpful tool in ranking cutting bills for their expected yield level. Overall, the model performs well for standardized cutting bills, but more work is needed to make the model generally applicable for cutting bills whose requirements are beyond the framework established in this study.<br>Ph. D.

Thesis (MSc .(Plant Production)) -- University of Limpopo, 2016<br>Delayed fruit harvest (DFH) or on-tree-fruit storage is a strategy being considered to extend the harvest season of late maturing ‘Reed’ avocado. However, avocado fruit growth beyond physiological maturity is accompanied by alterations in chemical and physical properties. Thus, the study aimed to investigate the effects of delayed harvest on tree productivity, mineral nutrition and post-harvest quality of late maturing ‘Reed’ avocado and further to evaluate the fruit quality response to varying ripening temperature regimes. As treatments, fruit were harvested early, mid and late in the season, with one month apart from each harvest during 2013 and 2014 seasons. Yield and fruit size were recorded at harvest. During each harvest time, two sets of fruit samples were collected to determine the fruit nutritional content while the second set was cold stored at 5.5°C for 28 days. After storage, fruit were ripened at 16, 21 or 25°C and evaluated for post-harvest disorders, pathological diseases and fruit physico-chemical properties. Yield dropped from 42 to 12 kg/tree from early to late harvest during 2013, while treatments showed no effect during 2014. Furthermore, treatments had no effect on fruit size during both seasons. Phosphorus content decreased by 40 and 23% from early to late harvest time during 2013 and 2014 seasons, respectively. Similar decreasing patterns were observed for K, Ca and Mg content. Zinc content remained constant during 2013; however, mid-season fruit maintained higher zinc levels during 2014 season when compared to early and late harvest time. Protein content was constant for early and mid-season fruit but significantly decreased during the late harvest in both seasons. Moisture content decreased from 74.0 to 65.0% from early to late harvest during both seasons. Starch, oil and ash content were high during late harvest time in both seasons; while crude fibre was high during the mid-harvest time when compared with early and late harvest time. Internal chilling injury increased with maturity and ripening temperature. In both seasons, higher temperatures induced higher anthracnose incidences during early and mid-harvest compared with late harvest time. Similarly, vascular browning was high on fruit ripened at 16°C during early and mid-harvest time but decreased on late harvest fruit during 2013. However, low ripening temperatures induced high incidences of vascular browning during 2014 season. Stem-end rot was high on fruit ripened at 16°C than 21 and 25°C during 2014 season. xvi Physico-chemical quality parameters showed similar behaviour in both seasons. Fruit lightness increased with ripening time regardless of ripening temperature during the early harvest, but remained constant during mid and late harvest. Hue angle (h0) and Chroma (C*) values were slightly reduced during ripening. Fruit ripened at 25°C had the highest respiration rate and reached a climacteric peak earlier (day 2) than fruit ripened at 21 and 16°C (day 4). Fruit firmness and weight loss were high and rapid at 25°C followed by 21 and 16°C regardless of the harvest time. Delayed harvest had no effect on yield and fruit size. Generally, nutritional content of avocado fruit increased with fruit maturity. Furthermore, fruit maturity played a major role in the response of fruit to ripening temperature. Higher temperature enhanced fruit ripening, but was conducive for development of post-harvest diseases. Keywords: Harvesting time, nutrition, yield, fruit size, ripening temperature, post-harvest quality

Almonds are one of the first commercial nut trees to bloom in early spring and thus are susceptible to temperature patterns prior to and during bloom which affect bloom timing, bloom length, pollination and nut set. Data used in this project include yearly dates of 90% bloom from 1996-2006, bloom length in days and final crop yields in pounds per tree for Nonpareil and Mission varieties. Data were collected from the University of California Cooperative Extension reports on the 1993-2006 Regional Almond Variety Trials in Butte, San Joaquin and Kern Counties. Temperature pattern models in the form of Chill Hours (Chill Hour Model), Chill Units (Chill Unit Model), Chill Portions (Chill Portion Model) and Growing Degree Hours (GDH°) (Heat Model) prior to bloom were used to predict the date of 90% bloom for each variety, site and year. Temperature model results were compared to averaged actual dates of 90% bloom by site and variety used to predict bloom timing (Calendar Model). The relationship between bloom length in days and GDH° during bloom and the relationship between bloom length, GDH° during bloom and final crop yields were also evaluated. The average error in predicting the 90% bloom date for both Nonpareil and Mission was smaller using the Calendar Model compared to the four temperature pattern models. The Chill Portion model did not have significantly higher average error in predicting the date of 90% bloom than the Calendar model in Nonpareil. The Chill Unit and Chill Portion models had smaller errors in predicting 90% bloom date than the Chill Hour or GDH° model in Mission. GDH° during bloom was positively correlated with bloom length. GDH° during the first four days of Nonpareil bloom was significantly correlated with crop yields, with each additional GDH° during bloom correlated with a 0.4 lbs./tree increase in crop yield. Further research is needed on specific temperature thresholds and their relationship to physiological changes during almond bloom and pollination. The practice of monitoring chilling and heat accumulation will allow growers to anticipate bloom, prepare to optimize bee activity during bloom, and plan for possible crop yield variations due to adverse weather conditions during bloom in almonds.

The percentage of low-grade material composing the annual hardwood lumber production in the U.S. is on the rise. As a result, finding markets for low-grade and low-value lumber has been identified as a top priority by researchers and industry associations. Computer simulation has been used by the manufacturing industry for several decades as a decision support tool. Simulation programs are commonly used and relied on by researchers and the industry alike to conduct research on various aspects of the rough mill from processing to recovery efficiency. This research used the ROMI-RIP and ROMI-CROSS simulation programs to determine specific conditions that led to optimal part yield when processing No. 3A Common, 4/4-thickness, kiln-dried, red oak lumber in rip-first and crosscut-first operations. Results of the simulations indicated that cutting bills with narrow part widths and short part lengths are conducive to obtaining optimal part yield while processing No. 3A Common lumber. Furthermore, it was found that as the percent of No. 3A Common lumber in a grade mix increases, part yields and sawing efficiencies decrease. The results also indicated that higher part yields will be obtained when processing short-length No. 3A Common lumber between 6 and 8 feet in length.<br>Master of Science