Dissertations / Theses on the topic 'Seedling yield'

The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.<br>Six lots of Deltapine (DP) 90 of different seed densities were planted at three planting rates in four tests in Arizona in 1985. The lowest density seed lot had significantly lower standard germination, cold test germination, field emergence, and lint yield than other seed lots. The highest density seed lot had slightly higher lint yield and field emergence than other lots on an average.

The effects of sulfur-containing amendments (H₂SO₄,Al₂(SO₄)₃ and gypsum) or crust formation, soil chemical properties, seedling emergence and yields of onions (Allium cepa), tomatoes (Lycopersicum esculentum) and chili peppers (Capsicum sp.) were studied on a Pima clay loam soil. Treatments were surface applied on a strip above the seeds. The chemicals influenced the penetrometer index, soil-pH, electrical conductivity, DPTA-extractable soil Fe, Cu, Zn, Mu and seedling emergence in two greenhouse experiments. Gypsum and H₂SO₄ increased seedling emergence while Al₂(SO₄)₃ reduced the soil-pH and EC more than H₂SO₄ and gypsum. Based upon penetrometer readings, H₂SO₄ was the best anti-crusting agent tested followed by gypsum and Al₂(SO₄)₃. At the end of the study, all soil samples were very low in KCl extractable Al, showing that Al toxicity was not responsible for seedling damage. Gypsum decreased levels of Mn and Zn but did not affect Fe and Cu. Al₂(SO₄)₃ increased Fe and Zn, decreased Cu but did not affect Mn. H₂SO₄ did not affect extractable Mn, Cu, Zn and Fe levels. In a field study using two water qualities at Safford, gypsum produced the most tomato seedlings whereas Al₂(SO₄)₃ and H₂SO₄ produced the least. Onion stand counts were not affected by the chemicals with either water. Gypsum, H₂SO₄ and Al₂(SO₄)₃ polymer produced the highest pepper stand counts with the saltier water but there were no differences with lower salt water. Tomatoes produced the highest yield with gypsum and lowest with H₂SO₄ and Al₂(SO₄)₃ with saltier water. With lower salt water, gypsum produced highest yield, followed by the H₂SO₄. Both H₂SO₄ treatments produce low yields. Onions showed no treatment response under lower salt water, while with saltier water, gypsum and H₂SO₄ produced the highest yields. Pepper yields were not affected by amendments with the lower salt water. Al₂(SO₄)₃ polymer, H₂SO₄ and gypsum increased yields with the saltier water. Varieties of peppers and tomatoes produced different yields in response to water quality in a supplementary field study.

Thesis (MScAgric)--University of Stellenbosch, 2004.<br>ENGLISH ABSTRACT: The influence of chemical seed treatments on the germination, seedling survival and yield of canola (cv. Varola 44) was investigated in a series of incubation studies, glasshouse experiments, as well as field trials in the canola producing areas in the Western Cape Province. Incubation experiments were conducted to compare germination and seedling growth of untreated (control) seed with that of seed treated at different application rates (0.5, 1.0 and 2.0 times the recommended) of Cruiser® and SA-combination (which consists of Thiulin® at 0.5g a.i.; Apron® at 0.0815 g a.i.; Gaucho® at 0.6125 g a.i. and Rovral® at 0.9975 g a.i.). The results indicated that seed treatment (all rates of SA-combination and highest rate of Cruiser) delayed germination and seedling growth, especially if the seed was subjected to the Accelerated Ageing Test. Glasshouse studies with pasteurised soil at different water contents, seed sources (storage periods) and planting depths confirmed the phytotoxic effects of the chemical seed treatments in the absence of soil borne pathogens. From the results it became clear that extreme water conditions (very wet or dry) increased the suppressing effect on germination and seedling growth, but that no phytotoxic reactions occurred in moist (favourable soil water conditions) soil, regardless of application rate of the chemicals used, planting depth and seed source. In a second glasshouse experiment conducted in moist soil (kept at 50% of field water capacity to prevent any toxic effects) from seven different localities that were naturally infested with pathogens, both chemicals proved to be effective where soil borne pathogens (Rhizocfonia so/ani and Pythium spp.) occurred. No clear trend could however be found due to either chemical or application rates used. Finally, field trials were conducted to study the effect of chemical seed treatments on the plant populations and yield of canola planted in different row widths (17 and 34 cm) and seeding rates (3, 5 and 7 kq.ha'). Results showed that treated seeds produced more plants.rn" and yielded more than untreated seeds at Roodebloem Experimental Farm, while the highest seeding rate produced significantly more plants.rn" (Roodebloem and Langgewens Experimental Farms), but not significantly higher yields than the lowest seeding rate at the same locality. Although row width did not have an effect on plant population, yield (Roodebloem 2003) was significantly less at the wider (34 cm) rows. As in earlier experiments, no consistent differences between the two chemicals used were found. These results clearly illustrated both the negative (in the absence of pathogens) and positive (where soil borne pathogens do occur) effects that chemical seed treatments may have on the germination, seedling growth and even yield of canola under local environmental and soil conditions. Because no significant differences were found between the chemicals used, both chemicals should be regarded as efficient. More research, especially under field conditions and with more cultivars, is needed before the registration of a chemical for seed treatment could be considered.<br>AFRIKAANSE OPSOMMING: Die invloed van chemiese saadbehandeling op die ontkieming, saailing oorlewing en opbrengs van canola (cv. Varola 44) is ondersoek in 'n reeks inkubasie studies, glashuis eksperimente en veldproewe in die canolaproduserende gebiede in die Wes Kaap Provinsie. Inkubasie eksperimente is uitgevoer om die ontkieming en saailing groei van onbehandelde (kontrole) saad te vergelyk met dié van saad wat behandel is teen verskillende dosisse (0.5, 1.0 en 2.0 keer die aanbevole) van Cruiser® en SA-kombinasie (wat bestaan uit Thiulin® teen 0.5g a.i.; Apron® teen 0.0815 g a.i.; Gaucho® teen 0.6125 g a.i. en Rovral® teen 0.9975 g a.i.). Die resultate het aangedui dat saadbehandeling (vir alle dosisse van SAkombinasie en die hoogste dosis van Cruiser) ontkieming en saailing groei vertraag, veral wanneer die saad onderwerp was aan die Versnelde Verouderings Toets. Glashuis studies met gepasteuriseerde grond by verskillende waterinhoude, saad bronne (stoor periodes) en plantdieptes, het die fitotoksiese effekte van die chemiese saadbehandelings bevestig in die afwesigheid van grondgedraagde patogene. Vanuit die resultate het dit duidelik geword dat ekstreme water toestande (baie nat of droog) die onderdrukkende effek op ontkieming en saailinggroei verhoog het, maar dat geen fitotoksiese reaksies plaasgevind het in klam (gunstige grondwater toestande) grond nie, ongeag die dosisse of chemikalieë gebruik, plantdiepte en saad bron. In 'n tweede glashuis eksperiment uitgevoer in klam grond (gehou by 50% van veldwaterkapasiteit om toksiese effekte te voorkom) van sewe lokaliteite wat natuurlik besmet was met patogene, was beide chemikalië effektief waar grondgedraagde patogene (Rhizoctonia so/ani en Pythium spp.) voorgekom het. Geen duidelike tendens is egter waargeneem vir enige van die chemikalieë of dosisse nie. Laastens is veldproewe uitgevoer om die effek van chemiese saadbehandelings op plant populasies en opbrengs te bepaal van canola geplant in verskillende rywydtes (17 en 34 cm) en saaidigthede (3, 5 en 7 kg.ha-1). Resultate het aangedui dat behandelde saad meer plante.rn" produseer en 'n groter opbrengs lewer as onbehandelde saad by Roodebloem Eksperimentele Plaas, terwyl die hoogste saaidigtheid betekenisvol meer plante.m" (Roodebloem en Langgewens Eksperimentele Plase), maar nie betekenisvol hoër opbrengste gelewer het as die laagste saaidigtheid by dieselfde lokaliteit nie. AI het rywydte nie 'n effek op plant populasie gehad nie, was opbrengs (Roodebloem 2003) betekenisvol minder by die wyer (34 cm) rye. Soos in vroeëre eksperimente is geen konsekwente verskille tussen die twee chemikalieë gevind nie. Hierdie resultate illustreer duidelik beide negatiewe (in die afwesigheid van grondgedraagde patogene) en positiewe (in die aanwesigheid van grondgedraagde patogene) effekte wat chemiese saadbehandelings op ontkieming, saailing groei en selfs opbrengs van canola onder plaaslike omgewings en grondtoestande kan hê. Omdat geen betekenisvolle verskille tussen die chemikalieë gevind is nie, moet beide chemikalieë as doeltreffend aanvaar word. Meer navorsing, veralonder veldtoestande en met meer kultivars, is egter nodig voordat die registrasie van 'n chemiese middel vir saadbehandeling oorweeg kan word.

The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.<br>Partial pre-germination of Deltapine 90 seed under oxygen and then drying prior to planting tended to speed and increase emergence in two tests in 1985, but did not increase lint yield.

Influence of tomato (Solanum lycopersicum L.) seedling grafting on the plant growth, fruit yield and quality, and disease tolerance were investigated using 3 cultivars (Big Beef, Celebrity, Cannonball) as scions and two Solanum species (B-blocking, Maxifort) as a rootstock in a randomized complete block design with three replications. The grafted plants were statistically higher in values for stem diameter, leaf chlorophyll, and fruit carotenoid contents. Similarly, the scion/rootstock combination ‘Big Beef/Maxifort’ and ‘Big Beef/B-blocking’ had prolonged days to maturity and gives a higher yield than the non-grafted ‘Big Beef’. Grafting seedling on ‘Maxifort’ and ‘B-blocking’ rootstocks improves the fruit quality like titratable acidity (TA), fruit firmness, but didn’t alter the pH, total soluble solid (TSS), lycopene and TSS/TA. Also, grafted treatment ‘Big Beef/Maxifort’ was found to be a highly disease resistant treatment when compared to the ‘Big Beef’ control with mean relative effect 0.074.

Orientadora: Leila Trevizan Braz<br>Banca: Joaquim Gonçalves Pádua<br>Banca: Antonio Baldo Geraldo Martins<br>Resumo: Os experimentos foram conduzidos em casa de vegetação do Setor de Olericultura e Plantas Aromático-Medicinais da FCAV-UNESP, Jaboticabal-SP, com o objetivo de avaliar seis métodos de enxertia em melão rendilhado e seus efeitos na produtividade em três épocas de cultivo. Para o delineamento experimental, foram realizadas análises conjuntas das três épocas de cultivo (Época 1 - 21-08-2007 a 17-12-2007; Época 2- 10-03-2008 a 22-08-2008; Época 3 - 10-07-2008 a 27-11-2008) com os tipos de enxertia, mais a testemunha. Cada característica também foi avaliada separadamente, utilizando-se do delineamento de blocos ao acaso, com sete tratamentos e três repetições. Os tratamentos foram representados por dois métodos de enxertia utilizados no Brasil para cucurbitáceas: fenda cheia e encostia; quatro métodos da Coreia: palito, bisel, palito sem raiz e bisel sem raiz; e a testemunha que não foi submetida à enxertia. Após a realização das enxertias, as mudas permaneceram em câmara com alta umidade até o pegamento, quando foram transplantadas para casa de vegetação e tutoradas na vertical. Foram avaliadas as seguintes características: diâmetros do porta-enxerto e enxerto, área foliar em três fases do cultivo, número de internódios, produção, dimensão dos frutos e sólidos solúveis. Na Época 3, observaram-se as maiores médias na maioria das características avaliadas, e foi considerada a mais indicada para a condução de mudas enxertadas. O tipo de enxertia não influenciou na maioria das características avaliadas. As enxertias tipo fenda cheia, encostia, bisel e bisel sem raiz resultaram em mais de 90% de pegamento e são as mais indicadas para melão rendilhado, uma vez que não ocorreram doenças de solo. Não houve diferença na produtividade entre os métodos de enxertia e o pé-franco.<br>Abstract: The works was carried in greenhouse at FCAV - UNESP, Jaboticabal - SP, Brazil, to evaluated six grafting methods in muskmelon and their effects on the productivity in three seasons cultivations.The experiment design was in randomized blocks with seven treatments and three replications. (Season 1: August 21th to December 21th 2007; Season 2: March 10th to August 22th 2008 and Season 3: July 10th to November 27th 2008). The treatments was two grafting methods utilized in Brazil to cucurbits: fenda cheia and encostia; four methods from Korea: hole insertion grafting, splice grafting, combination of root pruning and hole insertion grafting, and combination of root pruning and splice grafting, and the testimony, that not be grafted process. After the grafting process, the seedlings stayed inside the high humidity chamber until the success of grafting. After the evaluations of percent of grafting, the seedlings was moved to greenhouse. Was evaluated the caracteristics of fruits: diameter of rootstocks and scion, leave area, node number, yield, fruits dimensions and SST. The season 3, has the greatest medium on the most of caracteristics evaluateds and was considered the most indicated to seedlings grafted yield. The graftings methods didn't influenced most of caracteristics evaluateds. The grafting methods of fenda cheia, encostia, splice grafting and combination of root pruning and splice grafting, arrived more than 90% of grafting success and they are the most indicated to muskmelon. Didn't have diference on the yield to grafting methods and testimony.<br>Mestre

Made available in DSpace on 2014-06-11T19:28:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-26Bitstream added on 2014-06-13T20:37:30Z : No. of bitstreams: 1 ito_la_me_jabo.pdf: 499908 bytes, checksum: 23f1712014c2e833746e0e8814befd26 (MD5)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>Os experimentos foram conduzidos em casa de vegetação do Setor de Olericultura e Plantas Aromático-Medicinais da FCAV-UNESP, Jaboticabal-SP, com o objetivo de avaliar seis métodos de enxertia em melão rendilhado e seus efeitos na produtividade em três épocas de cultivo. Para o delineamento experimental, foram realizadas análises conjuntas das três épocas de cultivo (Época 1 – 21-08-2007 a 17-12-2007; Época 2- 10-03-2008 a 22-08-2008; Época 3 – 10-07-2008 a 27-11-2008) com os tipos de enxertia, mais a testemunha. Cada característica também foi avaliada separadamente, utilizando-se do delineamento de blocos ao acaso, com sete tratamentos e três repetições. Os tratamentos foram representados por dois métodos de enxertia utilizados no Brasil para cucurbitáceas: fenda cheia e encostia; quatro métodos da Coreia: palito, bisel, palito sem raiz e bisel sem raiz; e a testemunha que não foi submetida à enxertia. Após a realização das enxertias, as mudas permaneceram em câmara com alta umidade até o pegamento, quando foram transplantadas para casa de vegetação e tutoradas na vertical. Foram avaliadas as seguintes características: diâmetros do porta-enxerto e enxerto, área foliar em três fases do cultivo, número de internódios, produção, dimensão dos frutos e sólidos solúveis. Na Época 3, observaram-se as maiores médias na maioria das características avaliadas, e foi considerada a mais indicada para a condução de mudas enxertadas. O tipo de enxertia não influenciou na maioria das características avaliadas. As enxertias tipo fenda cheia, encostia, bisel e bisel sem raiz resultaram em mais de 90% de pegamento e são as mais indicadas para melão rendilhado, uma vez que não ocorreram doenças de solo. Não houve diferença na produtividade entre os métodos de enxertia e o pé-franco.<br>The works was carried in greenhouse at FCAV – UNESP, Jaboticabal – SP, Brazil, to evaluated six grafting methods in muskmelon and their effects on the productivity in three seasons cultivations.The experiment design was in randomized blocks with seven treatments and three replications. (Season 1: August 21th to December 21th 2007; Season 2: March 10th to August 22th 2008 and Season 3: July 10th to November 27th 2008). The treatments was two grafting methods utilized in Brazil to cucurbits: fenda cheia and encostia; four methods from Korea: hole insertion grafting, splice grafting, combination of root pruning and hole insertion grafting, and combination of root pruning and splice grafting, and the testimony, that not be grafted process. After the grafting process, the seedlings stayed inside the high humidity chamber until the success of grafting. After the evaluations of percent of grafting, the seedlings was moved to greenhouse. Was evaluated the caracteristics of fruits: diameter of rootstocks and scion, leave area, node number, yield, fruits dimensions and SST. The season 3, has the greatest medium on the most of caracteristics evaluateds and was considered the most indicated to seedlings grafted yield. The graftings methods didn’t influenced most of caracteristics evaluateds. The grafting methods of fenda cheia, encostia, splice grafting and combination of root pruning and splice grafting, arrived more than 90% of grafting success and they are the most indicated to muskmelon. Didn’t have diference on the yield to grafting methods and testimony.

Doctor of Philosophy<br>Department of Agronomy<br>Tesfaye T. Tesso<br>The lack of effective post-emergence weed control options is often highlighted as one of the major factors behind dwindling acreage under sorghum (Sorghum bicolor (L.) Moench) in the United States. The discovery of herbicide resistance sources in wild sorghum population and subsequent efforts to incorporate them into cultivated sorghum was received with much optimism to change weed management practices in sorghum. As the development of the technology advances, especially of the Acetolactate synthase (ALS) resistance, concerns over the temporary interveinal chlorosis and reduced seedling vigor in some of the resistant families became heightened. This thesis research is designed to shed light on the genetic basis of seedling chlorosis and assess its impacts on yield potential. The study has three parts; the first part is focused on identifying the genetic causes and plant mechanisms associated with the chlorotic phenotype. ALS herbicide resistant sister-lines expressing normal and chlorotic phenotypes were analyzed via RNA sequencing at four time points during seedling growth. The study identified several variants of genes coding chloroplast precursors and those that cause epigenetic modifications. Once confirmed, genetic markers can be developed to track these gene variants in the breeding population and eliminate segregates genetically prone to chlorosis/yellowing. The second part of the study focuses on assessing the effect of ALS resistance associated chlorosis on agronomic and nutritional parameters of sorghum inbred lines. A set of ALS resistant lines expressing different levels of the chlorotic phenotype were evaluated in replicated field trials and laboratory methods. Results showed that interveinal chlorosis delays flowering but does not have negative effect on yield and nutritional parameters with and without herbicide treatment. The last part addresses whether there is any yield drag that may be associated with herbicide resistance traits and foliar interveinal chlorosis. For this, we synthesized a large set (182) of hybrids from ALS resistant, ACCase resistant and regular (susceptible) seed and pollinator parents. The hybrids were then evaluated in three sets at multiple locations during the 2014 and 2015 crop seasons along with commercial checks. The results revealed that resistance to both herbicides do not cause any drag to grain yield. The traits also do not have any negative impact on grain and nutritional quality of resistant hybrids.

Blueberry though one of the most valuable berry plants is limited in its occurrence in Lithuania. One of the reason – is lack of local cultivars. Over 1993 – 2004 the largest blueberry germ plasm was established in Kaunas Botanical Garden at VDU. This collection has been used for breeding of new cultivars. Seedlings ‘No.11, ’‘No.16’ and ‘No.17’ were investigated in Kaunas Botanical Garden over 2002 – 2004. The investigation aimed at estimating of productivity, character of fruiting and biochemical composition of berries. The obtained result were compare with those of halth-highbush ‘Northcountry’. Fruiting of 4 – 6 year old bushes was estimated, mean earliness of fruiting, berry size, volume and average yield for 3 seedling numbers were determined. Seedlings numbers ‘No.11, ��‘No.16’ and ‘No.17’might be classified as early cultivars. The main port of the blueberry yield was obtained in the first picking, due to this mechanised picking might be applied. The plants produce tasty, good marketable appearance and biochemical composition. The best marketable appearance typical of ‘No. 17’, the biggest berries – ‘No. 11����. The most productive were ‘No. 16’ and ‘No. 17’, their mean productivity is two times higher than that of ‘Northcountry’.

O cultivo da cana-de-açúcar depara-se com a falta de tecnologias alternativas inovadoras para impulsionar sua produtividade diante dos crescentes custos de mão de obra e insumos, tornando-se essencial aumentar a produtividade da cana de forma sustentável. A cana-de-açúcar é comercialmente plantada, utilizando-se cortes de toletes ou gemas. Este método de cultivo está se tornando gradualmente antieconômico, devido ao elevado custo das \"áreas de viveiros\" usadas para a renovação de canaviais, que demandam mais de 20 por cento do custo total de produção para renovação/novos plantios. Dessa forma, necessita-se de métodos alternativos de plantio, que impulsionem a produtividade da cana-de-açúcar sobre princípios de um planejamento adequado; entre outras práticas, devem estar inclusas a formação de viveiros sadios, com otimização de áreas destinadas à multiplicação de mudas e também a escolha das melhores opções entre os materiais genéticos para a formação do canavial. Este trabalho baseia-se na hipótese de que, para viveiros de cana-de-açúcar, exista uma combinação mais adequada entre a lâmina de irrigação/intensidade do déficit hídrico e a posição da gema ao longo do colmo; desta forma, aumenta-se a produtividade de gemas de cana-de-açúcar, que serão utilizadas no plantio do sistema de mudas-pré-brotadas (MPB). O objetivo deste trabalho foi avaliar, no que se refere ao viveiro de mudas, o efeito de quatro lâminas de irrigação, quatro intensidades de déficit hídrico na fase de maturação, quatro posições ao longo do colmo para oito variedades de cana-de-açúcar irrigadas por gotejamento, assim como também a produtividade por área e os custos de produção de gemas viáveis de cana-de-açúcar. O experimento foi conduzido no município de Piracicaba - SP, no Departamento de Engenharia de Biossistemas da Escola Superior de Agricultura \"Luiz de Queiroz\" (ESALQ/USP), em ambiente protegido (estufa). O delineamento experimental adotado foi em blocos inteiramente aleatorizados, com três blocos completos. Os tratamentos foram distribuídos em esquema fatorial (4x4x4x8), totalizando-se assim 511 tratamentos e 1536 parcelas experimentais. Os tratamentos testados foram: lâmina de irrigação ao longo do ciclo, com quatro níveis (Lâmina); intensidade do déficit hídrico na fase final do ciclo para maturação da cana-de-açúcar, com quatro estratégias de restrição hídrica (Maturação); posição da gema ao longo do comprimento do colmo, com quatro posições (Posição); e variedade comercial de cana-de-açúcar, com oito variedades (Variedade). Considerando-se que o presente estudo foi desenvolvido através de irrigação por gotejamento de alta frequência sob irrigação plena e irrigação com déficit, pode-se concluir que: a) a lâmina de irrigação que repõe o total de água requerido com alta frequência (L100) promove um aumento médio de 42% no total de gemas viáveis produzidas por hectare, comparado com o fornecimento de metade da lâmina de irrigação requerida (L50); b) as gemas localizadas no segundo quarto do dossel da touceira tem maior capacidade de pegamento, bem como as próximas do ápice; c) a adoção de déficit hídrico na fase pré-colheita (estratégias de maturação) em condições de irrigação plena (L100) podem reduzir em média 11% o número de gemas viáveis por hectare; d) a produtividade da água para gemas de cana-de-açúcar (2,88 à 3,17 litros gema-1) não tem relação com a lâmina de irrigação ou a estratégia de maturação adotada, sendo influenciada somente pelo material genético utilizado (variedade); e) as estratégias de restrição do volume de água aplicado (L50, L75 e L125) oneram em até 51% os custos de produção para cada gema viável produzida, comparado à irrigação plena (L100).<br>Sugarcane crop is facing a difficult road ahead due the rising input and labor costs and the lack of innovative alternative technologies to boost productivity. Thus, it is essential not only increase the productivity of sugarcane, but also keep it in a sustainable way, had conserving limited resources throughout time. To accomplish this, there is a strong necessity to use alternative methods of production to boost sugarcane productivity on the principles of \'\'more with less\'\'. More than ever, the answer refers to proper planning, which includes among other practices, the formation of healthy nursery, with definable areas intended to multiplication of seedlings and the choice of the best options among the available materials for the formation of cane field. Sugarcane is cultivated using cuts of stalks or bud chips and this cultivation method is gradually becoming uneconomical due the cost of \"nurseries areas\" used for renew old areas, requiring more than 20 percent of the total production cost for renovation/new plantings. This work has the hypothesis that for sugarcane, there is a better combination of water depth / intensity of water stress and bud chip position along the stem, in order to maximize the fixation / development of buds. The objective is evaluate the effect of four irrigation levels, four water stress intensities in the maturation phase, four positions along the stem, for eight varieties of sugarcane submitted to drip irrigation, analyzing the related variables quality seedlings (productivity and cost of viable buds of sugarcane). The experiment was conducted in Piracicaba - SP, in the research area of the Department of Biosystems Engineering of the College of Agriculture \"Luiz de Queiroz\" (ESALQ / USP), in a protected environment (greenhouse). The experimental design was completely randomized blocks, with 3 complete blocks. The treatments were arranged in a factorial design (4x4x4x8), totaling 511 treatments and 1536 experimental plots. The treatments were: water depth during the cycle with 4 levels (Water depths); commercial variety of cane sugar, with 8 varieties (Variety), intensity of water deficit in the final phase of the maturation of sugarcane, 4 water restriction strategies (maturation); and bud chip position along the stem length, 4 position (position). Considering the conditions in which this study was developed: drip irrigation high frequency under full irrigation and irrigation deficit, it can be concluded that: a) The water depth that returned the total water required in high frequency (L100) promotes an average of 42% increase in total viable bud chips produced per hectare, compared with when it was supplied half of the required water depth (L50); b) Bud chips located in the second part of the canopy has a higher fixation capacity, as well as the buds located at the top; c) The adoption of water deficit in the pre-harvest phase (maturity strategies) in full irrigation conditions (L100) can reduce an average of 11% the number of viable buds per hectare; d) The water productivity of sugarcane bud chip (2,88 à 3,17 litros gema-1) has no relation to the water depth or adopted maturation strategy, being influenced by the used genetic material (variety); e) The restriction water strategies applied (L50, L75 and L125) can increase up to 51% of the costs for each viable bud produced compared to full irrigation (L100).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Aiming to characterize the main transgenic soybeans cultivars used in Rio Grande do Sul, experiments were conducted during the 2007/2008 season, in Santa Maria/RS. In the field, the cultivars Relmo Anta RR 82, A 6001 RG, A 8000 RG, FUNDACEP 53 RR, FUNDACEP 54 RR, FUNDACEP 56 RR, BRS 244 RR, and CD 214 RR CD 219 RR, drilled at seeds rates of 250, 400 and 550 thousand seed ha-1 and at row spacing of 0.30, 0.45 and 0.60m. The variables were: grain yield, yield components, distribution of income in different strata of the plant, morphological characteristics, rate of soil covering and amount of light incident on the canopy. The experimental design was a randomized blocks, with 4 repetitions in trifatorial outline (9 cultivars x 3 seed rates x 3 row spacing). In laboratory, tests of peroxidase reaction had been carried through only using the tegument of the seeds or the entire seeds and also seedling color for 50 soybean cultivars. For the grain yield cultivars CD 214 RR and FUNDACEP 53 RR had the best results (3589 and 3530 kg ha-1, respectively). For the distribution of income in the plant strata, there is interaction between density of planting and row spacing, which indicate the trends for each cultivar. For the amount of light incident on the canopy, the interactions between the factors of planting density, row spacing, timing of the cycle of development and level of the canopy, combined with the architecture of each cultivar define the amount of light intercepted, after flowering. The morphological response of each cultivar is different for every situation tested, indicating the need for understanding the behavior of each material, to select the practices to maximize the yield. The use of the test of reaction of peroxidase used the entire seed can be used of so efficient form how much the traditionally used method (tegument). The identification of the seedling color may be an early way to identify varietal blend.<br>Com o objetivo de caracterizar as principais cultivares transgênicas de soja utilizadas no Rio Grande do Sul, foram realizados experimentos durante a safra agrícola 2007/2008, em Santa Maria/RS. Em campo, as cultivares Relmo Anta 82 RR, A 6001 RG, A 8000 RG, FUNDACEP 53 RR, FUNDACEP 54 RR, FUNDACEP 56 RR, BRS 244 RR, CD 214 RR e CD 219 RR foram submetidas às densidade de semeadura de 250, 400 e 550 mil semente ha-1 e aos espaçamentos entre linhas de 0,30, 0,45 e 0,60m. As variáveis avaliadas foram: rendimento de grãos, componentes do rendimento, distribuição do rendimento em diferentes estratos da planta, características morfológicas, taxa de cobertura do solo e quantidade de luz incidente no dossel. O delineamento experimental utilizado foi o de blocos ao acaso, com 4 repetições, no esquema trifatorial (9 cultivares x 3 densidades de semeadura x 3 espaçamentos entre linhas). Em laboratório, foram realizados testes de reação da peroxidase utilizando somente o tegumento das sementes ou as sementes inteiras e também coloração do hipocótilo para 50 cultivares de soja. Para o rendimento de grãos as cultivares CD 214 RR e FUNDACEP 53 RR apresentaram os melhores resultados (3589 e 3530 kg ha-1, respectivamente). Para a distribuição do rendimento nos estratos da planta, existe interação entre densidade de semeadura e espaçamento entre linhas, os quais indicam as tendências para cada cultivar. Para a quantidade de luz incidente no dossel, as interações entre os fatores densidade de semeadura, espaçamento entre linhas, época do ciclo de desenvolvimento e nível do dossel, aliados à arquitetura de cada cultivar definem a quantidade de luz interceptada, após o florescimento. A resposta morfológica de cada cultivar é diferenciada para todas as situações testadas, indicando a necessidade do conhecimento do comportamento de cada material, para a escolha das práticas que visem maximizar o rendimento de grãos. O uso do teste de reação da peroxidase utilizando a semente inteira pode ser utilizado de forma tão eficiente quanto o método tradicionalmente utilizado (tegumento). A identificação da coloração do hipocótilo pode ser uma forma precoce de identificar mistura varietal.

Studies were carried out at the Safford Agricultural Center using some soil amendments as anti-crusting agents. The results are promising in terms of improved stands on soils subject to crusting. Additional research is needed in order to determine proper rates which will reduce crusting without being toxic to the emerging seedlings.

The effects of subjection of 15-day-old plants of tomato (Lycopersicon esculentum L. 'Contessa') to low night temperature (LNT) of 4°C for up to 21 nights and pre-chilling application of 10% sucrose solution on vegetative, reproductive and yield responses were examined under greenhouse conditions. Chilled seedlings exhibited severe inhibition of growth, with the degree of inhibition increasing with length of chilling. While sucrose treatment (ST) reduced such inhibition and promoted subsequent recovery, it transiently inhibited growth of the unchilled controls. In the long-term, inhibition of growth was observed only for the 0%-sucrose-treated plants cooled for 21 nights. Although LNT lowered the position of the first inflorescence in a direct relation to duration of exposure, this effect was reduced by ST. LNT had no lasting effects on the reproductive and productivity responses of the first two inflorescence (FTI), earliness of flowering, or potential yield and quality. ST promoted flowering of only the 21-day-cooled plants as well as numbers of flowers, fruit set and large fruit responses of FTI. The results indicate that, although early chilling stunts seedling growth, plants may recover at a later favorable temperature without loss to their reproductive capacity or yielding potential.

The association between individual plant performance and seed yield variability within and between field pea crops was investigated. In 1988/89 six F8 genotypes with morphologically distinct characteristics were selected from a yield evaluation trial. Analysis of the individual plant performance within these crops indicated an association between low seed yields and the location and dispersion of plant harvest index (PHI) and plant weight (PWT) distributions. The analyses also showed there was a strong linear relationship between the seed weight (SWT) and PWT of the individual plants within each crop, and that the smallest plants tended to have the lowest PHI values. A series of 20 simulations was used to formalize the relationships between SWT, PWT and PHI values within a crop into a principal axis model (PAM). The PAM was based on a principal axis which represented the linear relationship between SWT and PWT, and an ellipse which represented the scatter of data points around this line. When the principal axis passed through the origin, the PHI of a plant was independent of its PWT and the mean PHI was equal to the gradient of the axis. However, when the principal axis had a negative intercept then the PHI was dependent on PWT and a MPW was calculated. In 1989/90 four genotypes were sown at five plant populations, ranging from 9 to 400 plants m⁻². Significant seed and biological yield differences were detected among genotypes at 225 and 400 plants m⁻². The plasticity of yield components was highlighted, with significant genotype by environment interactions detected for each yield component. No relationship was found between results for yield components from spaced plants and those found at higher plant populations. The two highest yielding genotypes (CLU and SLU) showed either greater stability or higher genotypic means for PHI than genotypes CVN and SVU. Despite significant skewness and kurtosis in the SWT, PWT, and PHI distributions from the crops in this experiment, the assumptions of the PAM held. The lower seed yield and increased variability in PHI values for genotype CVN were explained by its higher MPW and the positioning of the ellipse closer to the PWT axis intercept than in other genotypes. For genotype SVU, the lower seed yield and mean PHI values were explained by a lower slope for the principal axis. Both low yielding genotypes were originally classified as having vigorous seedling growth and this characteristic may be detrimental to crop yields. A method for selection of field pea genotypes based on the PAM is proposed. This method enables the identification of weak competitors as single plants, which may have an advantage over vigorous plants when grown in a crop situation.

IzvodIZPet hibrida suncokreta (Sremac, Oliva, Cepko, NS-H-111 i Sumo 2 OR) gajena su tokomvegetacionih sezona 2010. i 2011. godine na oglednom polju Instituta za ratarstvo ipovrtarstvo, Novi Sad, na Rimskim &scaron;ančevima i na oglednom polju Poljoprivredne stručneslužbe Zrenjanin. Laboratorijski deo ogleda izveden je u Laboratoriji za ispitivanje semenaInstituta za ratarstvo i povrtarstvo iz Novog Sada i Biohemijskoj laboratorijiPoljoprivrednog fakulteta u Novom Sadu. Cilj istraživanja je bio da se utvrdi da li semenskimaterijal, poreklom sa istog lokaliteta i iste parcele, u procesu dorade semena tj. odvajanjasemena po frakcijama menja kvalitet, kao i da li ovakav način dorade semenskog materijalautiče na prinos i komponente prinosa semena, kao i na sadržaj i prinos ulja odabranihhibrida suncokreta. Takođe, cilj je bio i da se utvrdi da li nedostatak primarnog korena kodponika suncokreta dovodi do statistički značajnog smanjenja prinosa semena i ulja, kao ikakav uticaj ima na komponente prinosa suncokreta. Analizirane su sledeće osobine:klijavost i vigor semena, enzimska aktivnost, nicanje u polju, nakupljanje suve materije (pobiljnim organima i ukupno po biljci), visina stabla, prečnik glave, prinos semena, masa 1000semena, sadržaj ulja i prinos ulja. Statistička obrada podataka izvr&scaron;ena je primenom analizevarijanse trofaktorijalnog ogleda, prema modelu podeljenih parcela. Iz tabele analizevarijanse je prikazana verovatnoća značajnosti razlika po F-testu, a na osnovu uče&scaron;ća usumi kvadrata tretmana određen je procentualni udeo svakog faktora u ukupnojvarijabilnosti. Takođe su izračunate i LSD vrednosti za poređenje razlika između tretmanaposmatranog faktora, na pragovima značajnosti od 1 i 5%. Utvrđena je i korelacionazavisnost posmatranih osobina. Rezultati analize varijanse pokazali su visoko značajnouče&scaron;će glavnih faktora (godine, lokaliteta, frakcije semena, tipa ponika), kao i njihovihmeđusobnih interakcija za većinu ispitivanih osobina. Na vrednosti ispitivanih osobinanajveći uticaj imala je godina istraživanja, a zatim lokalitet. Frakcija semena je imala visokoznačajan uticaj na klijavost semena, nicanje u polju, nakupljanje suve materije, prinossemena i prinos ulja. Tip ponika je imao visoko značajan uticaj na enzimsku aktivnost<br>Five sunflower hybrids (Sremac, Oliva, Cepko, NS-H-111, and Sumo 2 OR) were grown in2010 and 2011, on experimental fields of the Institute of Field and Vegetable Crops NoviSad - Rimski &Scaron;ančevi, and experimental fields of the Agricultural Service Zrenjanin.Laboratory tests were conducted at Laboratory for Seed Testing of the Institute of Fieldand Vegetable Crops Novi Sad, and Biochemical Laboratory of the Faculty of Agriculture,University of Novi Sad. The aim of this research was to determine whether seed materialfrom the same locality and the same field lot changes quality during seed processing, i.e.dividing seed lot into fractions, and additionally whether this type of seed processingaffects seed yield, seed yield components, oil yield, and oil content of the selectedsunflower hybrids. The aim was also to determine if missing primary root in sunflowerseedlings results in statistically significant decrease of seed and oil yield, and establish howit influences sunflower yield components. The following traits were examined: seedgermination and vigour, enzymatic activity, field emergence, dry matter accumulation (inplant organs and in the whole plant), stem height, head diameter, seed yield, 1000 seedmass, oil content and oil yield. Statistical analysis of data was performed by analysis ofvariance of the trifactorial trial using the split-plot design model. Table of analysis ofvariance shows the probability of significance of differences by F-test, and based on theparticipation in the treatment sum of squares, percentage ratio of each factor wascalculated in the total variability. LSD values at 1 and 5% were computed to comparedifferences between treatments of the observed factor. Correlation dependence betweenthe observed traits was determined. Results of the analysis of variance showed a highlysignificant participation of the main factors (year, locality, seed fraction, type of seedling),and their mutual interactions for the majority of the examined traits. Year and locality hadthe highest effect on the value of the examined traits. Seed fraction had highly significanteffect on seed germination, emergence, dry matter accumulation, seed yield, and oil yield.Type of seedling had a highly significant effect on the enzymatic activity, seed yield, oilcontent, and oil yield.

The objective of this research was to determine the relationship between seedling root length and seed yield in spring canola. Field and growth room experiments were conducted using the same eight genotypes. In the field experiment, root length and root area had a strong positive relationship to seed yield with R2 values at the 1-2 leaf stage of 0.90 and 0.93, respectively. Shoot dry weight had a strong positive relationship to seed yield at the cotyledon stage, with an R2 of 0.99. In the growth room, root length was compared to short- and long-term seed yield. The R2 values when root length was compared to short- and long-term seed yield were 0.95 and 0.96, respectively.

碩士<br>國立中興大學<br>園藝學系<br>82<br>Greenhouse and field experiments were conducted to study the influence of seedling ages (4、6、8 and/or 10 weeks) on growth and early yield of fresh-market tomato. Older seedlings in plug tray (20ml/plug) showed bigger plant size at transplanting in all three cultivars. The root specific activity of seedlings transplanted on November 17, 1993 increased after transplanting, but the root specific activity of 4 week old seedlings transpl- anted on December 2, 1993 were higher than other seedling. Four old seedlings transplanted on November 17, 1993 and December 2, 1993 had the best recovery from transplanting. There was no significanct difference on days to flowering of seedlings transplanted on December 4, 1993 and January 15, 1994 either among cultivars or among seedling ages. The first node of inflorescence(FNI) were not different among cultivars. There was a quardratic response of age upon FNI for seedlings transplanted on December 4, 1993 but the response was linear for seedlings transplanted on January 15, 1994."Known You 202" had the highest early yield for December 4, 1993 transplanting had the highest early yield for January 15, 1994 transplanting. Ten week old se- edlings had the highest early yield for both experiments transpl- anted on December 4, 1993 and on January 15, 1994. The diffreence between three planting seasons were also exam- ized. Seedlings transplanted on September 22, 1993 had the high- est plant height and leaf area. However, seedlings transplanted on November 17, 1993 had the highest number of nodes and leaves. The plant size of seedlings transplanted on December 2, 1993 were significantly smaller than seedlings transplanted in Sep- tember and November .

碩士<br>明道大學<br>材料暨系統工程研究所<br>95<br>Switchgrass (Panicum virgatum L.) is a C4 perennial grass grown naturally in most of the central and eastern United States. A stand of switchgrass can grow vigorously over 10 years, resist drought, and survive with low fertilizer inputs. Thus, the U.S. Department of Energy has identified switchgrass as the most promising species for development into herbaceous biomass fuel crop. Switchgrass is also cultivated for the purpose of soil reclamation and habitat development of grassland birds. Switchgrass is as a multi-purpose crop with ecological function, soil conservation and bioenergy production. However, studies on switchgrass cultivation in Taiwan are very limited. In order to assess the feasibility of establishment of this multi-purpose crop in Taiwan, it is required to do detailed researches on cultivation management of switchgrass. In this study, two ecotypes of switchgrass, Alamo (A) and Blackwell (B), were selected for pot experiments. Seedling were grown in pots containing Yuliao soil and were maintained in a greenhouse for 6 months. Nitrogen (N) was applied at the rate of 0, 25, 50, 125 kg ha-1. Soil moisture levels were controlled by watering at 2 days (2D), 5 days (5D) and 8 days (8D) intervals. The results revealed that soil moisture influenced the tiller number, plant height, chlorophyll index, and tissue dry weight of switchgrass plants more significantly than nitrogen application. Tiller number and plant height of Alamo were significantly higher than that of Blackwell. Tiller number and plant height could be enhanced by increasing the nitrogen application rate and watering interval. Effects of nitrogen application and soil moisture on the tiller number and plant height were more prominent on Alamo than those on the Blackwell. Tiller number and plant height are considered as the evaluation factors for indicating the biomass yield to be harvested. The results showed that the effects of nitrogen application and soil moisture on the dry weight of aboveground tissues were more pronounced on Alamo than on Blackwell. On the other hand, the biomass yield of underground tissues of both the cultivars was influenced by the watering intervals; the dry weight of underground tissues was significantly increased with the increase in soil moisture levels resulting from frequent watering. Moreover, Alamo yielded more dry weight of underground tissues than Blackwell. Establishment of Alamo would be more beneficial for soil carbon sequestration than that of Blackwell. However, nitrogen application rate did not dshow a consistent positive response on the dry weight of underground tissues harvested. In conclusion, the morphological growth pattern and biomass yield of Alamo cultivar showed its strong ability to be a successful candidate for biofuel feedstock production in Taiwan, but the Blackwell cultivar has limited usefulness in teams of biofuel production because of low biomass yield.

Existing evidence suggested that nursery inoculation with Trichoderma harzianum and arbuscular mycorrhizal fungi (AMF) could reduce deleterious effects of biotic and abiotic stresses and improve seedling quality, fruit yield and quality of tomato (Solanum lycopersicum L.). However, studies of their combined inoculation on seedling growth, fruit yield and quality of tomato plants are not well-documented. Experiments were carried out to investigate the combined effect of T. harzianum and AMF on tomato crop performance under various conditions. When combined with a T. harzianum and AMF mixture, seaweed extract from Ecklonia maxiama inhibited AMF root colonisation of tomato seedlings. Treating seedlings with a mixture of T. harzianum and AMF reduced the incidence of Verticillium wilt in tomato grown in a nethouse at early season, with negligible effect on fruit yield. Further investigations were initiated to find out whether T. harzianum and AMF were efficient when applied as a mixture or alone, at different inoculation times. Co-inoculation with T. harzianum and AMF (Glomus mosseae) improved seedling growth and development, except when both fungi were simultaneously applied two weeks after sowing. When the seedlings were allowed to grow up until full harvest in a greenhouse, both fungal inoculants increased total yield and marketable yield, but these increases were not significant. Furthermore, inoculation with AMF increased the percentage of extra-large fruit. Field experiments conducted under commercial tomato production confirmed greenhouse studies. Inoculation of tomato with T. harzianum and AMF, either alone or in combination increased early fruit yield (four first harvesting weeks). Throughout the studies, percentage AMF root colonisation in seedlings and plants remained low, despite nursery inoculation. Field experiments investigated the effects of AMF-inoculated transplants combined with biochar-amended soils on AMF root colonisation and their resultant effects on overall crop performance and microbial community structure. Biochar had no effect on AMF root colonisation, and also when combined with AMF, it had no influence on tomato productivity. Interestingly, biochar altered the fungal community while AMF might have influenced the bacterial community such as plant-growth promoting rhizobacteria, which are associated with improved plant growth, nutrient uptake and disease control in the rhizosphere. These benefits could contribute to improved yield and fruit quality. In conclusion, although the results were variable, there was a clear indication that T. harzianum and AMF can play an important role in tomato production.<br>Thesis (PhD)--University of Pretoria, 2012.<br>Plant Production and Soil Science<br>unrestricted

Thesis (M.Sc. (Horticulture)) -- University of Limpopo, 2017.<br>Root-knot (Meloidogyne species) nematodes are economically destructive pathogens of over 3000 species, whereas others have resistance to Meloidogyne species. Wild watermelon (Cucumis africanus) and wild cucumber (Cucumis myriocarpus) are highly resistant to Meloidogyne species, particularly M. incognita and M. javanica. The two Cucumis species are used in inter-generic grafting with watermelon (Citrullus lanatus) as nematode resistant rootstocks. Also, the two Cucumis species are used in traditional medicine and in plant-parasitic nematode management as phytonematicides. The form of nematode resistance, which is essential in plant breeding, is not documented for the two Cucumis species. The objective of this study was to determine the form of nematode resistance in the two Cucumis species to M. incognita and M. javanica under greenhouse conditions. Four parallel experiments were each conducted under greenhouse conditions. Uniform six-week old Cucumis seedlings were transplanted into 250 ml polystyrene cups filled with 200 ml growing medium of steam-pasteurised fine sand. A week after transplanting, Cucumis seedlings were each infested by dispensing approximately 100 M. incognita second-stage juveniles (J2) or M. javanica J2 using a 20 ml plastic syringe by placing into 5-cm-deep furrow around the seedling stem and covered with growing medium. Treatments (periodic harvest intervals) were arranged in a randomised complete block design, replicated five times. Five seedlings from each experiment were harvested every second day, for 30 days, with stained roots being assessed for necrotic spot (suberised cells) number, giant cell number, proliferation of rootlet interference number and root gall number. Periodic harvest intervals were highly significant (P ≤ 0.01) on necrotic spot number, proliferation of rootlet interference number and root gall number in C. africanus-M. incognita relations, but were not significant for giant cell number. Treatments contributed 59, 64 and 50% in total treatment variation (TTV) of necrotic spot number, proliferation of rootlet interference number and root gall number, respectively. Harvest period had highly significant effects on necrotic spot number, giant cell number, proliferation of rootlet interference number and root gall number in C. africanus-M. javanica relations. Treatments contributed 55, 71, 63 and 59% in TTV of necrotic spot number, giant cell number, proliferation of rootlet interference number and root gall number, respectively. Periodic harvest intervals were significant (P ≤ 0.05) on giant cell number and highly significant on root gall number in C. myriocarpus-M. incognita relations. However, there were no significant treatment differences on necrotic spot number and proliferation of rootlet interference number. Treatments contributed 57 and 57% in TTV of root gall number and giant cell number, respectively. Harvest period had highly significant effects on giant cell number, proliferation of rootlet interference number and root gall number, but were not significant on necrotic spot number in C. myriocarpus-M. javanica relations. Treatments accounted for 67, 49 and 53% in TTV of giant cell number, proliferation of rootlet interference number and root gall number, respectively. In conclusion, the mechanism of resistance to M. incognita and M. javanica in both C. africanus and C. myriocarpus was post-infectional nematode resistance, which has attributes for introgression into commercial nematode-susceptible Cucumis cultivars.<br>Agricultural Research Council (ARC), National Research Foundation of South Africa; and the ARC-Universities Collaboration Centre for Smallholder Farmers

碩士<br>國立中興大學<br>園藝學系<br>88<br>Tomato cultivars Known- You 301 and Red Crown were used in this study. Tomato seedling were grown in high and low elevations at ching- jing farm, Nantou and at Shang-sheng nursery, Chiayi, respectively. The seedlings, then, were transplanted twice into the plots at Tainan District Agricultural Improvement Station in September and October, 1998 with three different densities to evaluate seedling-growing condition and plant density on the growth and yield of tomato. Results of the cv. Known- You 301 indicated that the stem diameter of the seedling grown at high elevations is larger but shorter than that grown at low elevations. No significantly difference was observed in the node of flower initiation among the seedlings from high or low elevations and planted in September, while the seedlings planted in October, high elevations plants were found with 6.3 nodes lowest for flower initiation. On the cv. Red Crown, Seedling quality was found the same as cv. Known-You 301 ignoring the seedling grown elevations. Seedling grown at high elevations and transplanted in September and October were found with 1.2 and 3.6 nodes, respectively, lower of flower initiations than those cultivated at low elevations. On the cv. Known-You301. Data accumulation of the harvestings in 12 weeks. Total fruit numbers, average fruit weight, and total yield for the plants planted in October were higher than those planted in September. Plants from high elevations seedlings were higher yield and more fruits in the first 2 and 4 weeks of harvestings. The yield per 3m2 of plants from high elevations seedlings was 0.8 ㎏ in the first 2 weeks and accumulated to 5.1㎏ in the 4th weeks, while the of yield plants form low elevations seedling was from 0.2㎏ to 2.9㎏. Since then elevations of seedling raising did not significantly affect the yield. Among the plant densities tested, one plant at a planting hill and with 25㎝ between plants had the highest fruit number, however, no significantly difference was observed in fruit size and average fruit weight. The plot with one plant/25㎝/hill between plants produced 2.8㎏ more than that with on plant/50㎝/hill between plants planted in September or October. “Red Crown” tomato, plants planted in October were with higher yield, more fruits and larger average fruit weight than those planted in September in the first（2wks）, 2nd（4wks）and 3rd（6wks）harvestings, total yield and fruit number from the seedlings grown at high elevations were higher than that from the low elevations seedling. Average fruit weight was no significantly difference between the seedling-raising elevations in the first and 2nd harvestings. After 4 weeks or after the 2nd harvesting, average fruit weight from the low elevations seedlings was larger than that from the high elevations seedlings. The yield of plants from high elevations seedling in each experimental units was 0.3㎏ of fruit in the first 2 weeks and accumulated to 9.7㎏ in the 6th weeks, but the yield of plants from low elevations seedlings was from 0 to 7.6㎏. No significantly difference was observed in yield after 6 weeks. Among the three densities, yield of the treatment with one plant / hill was the highest than the other two. The plot with one plant/25㎝/hill between plants produced 4.1㎏ more than that with on plant/50㎝/hill between plants in September or October.

The challenge of food security requires that agricultural production is no longer based on a narrow genetic material present in conventional crops. Whereas conventional crops have been genetically improved to suit management practices of the modern farmer, the future farmer requires that there be access to a wide variety of genetic material for economic exploitation and to respond to the challenges of climate change in a sustainable fashion. This study was designed to learn about production of wild water melon [Citrullus lanatus (Thunb.) Matsumura and Nakai] from seed germination, seedling establishment and field crop production. The specific objectives of the study were (a) to determine the effect of water stress on three landraces of watermelon differing in seed colour and provenance during seedling establishment, (b) to determine the effect of planting date on crop growth and yield under field conditions, and (c) to relate proline accumulation to water stress in wild watermelon. Three seedlots, ‘B’, ‘DB’ and ‘VDB” were derived from seeds collected from subsistence farming communities of the Eastern Cape, and KwaZulu-Natal. Following one season of seed production in Pietermaritzburg, KwaZulu-Natal, seeds were tested for germination capacity, before seedlot response to water stress was determined in three substrates made of pine bark, a 1:1 mixture of fine sand and pine bark and fine sand only. The substrates were kept at 75% FC, 50% F.C and 25% F.C., to create varying levels of water regimes during 12 weeks of seedling growth in a glasshouse (16/21oC (day/night) and 60% RH). Leaf proline content was determined at seedling harvest. Crop production under field conditions occurred at one site with three planting dates late September 2008, November 2008 and January 2009, respectively. There were significant differences among seedlots with respect to seed quality and seedling yield, which consistently showed that B > VDB > DB. The differences in seedlots continued in the same order even in response to field conditions. Wild watermelon was responsive to water stress during seedling growth, but high water regimes compromised water use efficiency. Proline accumulation correlated with water stress. The best plant growth and yield under field conditions was obtained when planting occurred in September, followed by November and January plantings, respectively. Early planting was also associated with high crop growth rate and larger fruit size. It is concluded that despite being a desert crop, wild watermelon responds to water deficits during seedling growth. Results of field studies cannot be conclusively used to determine crop response to water stress, although they gave a good indication of crop response to different conditions of rainfall and temperature at the study site from September to March.<br>Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

The taro landraces that are most preferred by farmers from Umbumbulu, KwaZulu-Natal were identified through focus group discussions with farmers. Farmers ranked taro landraces on the basis of preference as determined by economic value, social significance, ecological importance and food characteristics. Using pairwise ranking, the farmers' preference of taro landraces across all locations was found to be in the following order: Dumbe-dumbe, Mgingqeni, Pitshi and Dumbe-lomfula. Dumbe-dumbe was identified as the currently actively cultivated taro whereas Mgingqeni was regarded as a less desirable cultivated taro. Pitshi was regarded as an antiquated landrace and Dumbe-lomfula was generally regarded as a taro type of no economic, social or food value that grew on river banks as a wild species. Glasshouse and field studies were conducted to determine the effects of temperature and growing location [Pietermaritzburg (UKZN) and Umbumbulu] on emergence, plant growth and yield of taro. Starch and mineral composition of taro corms were determined in harvest-mature corms. Effects of three day/night temperature levels (22/12°C, 27/17°C and 33/23°C) were examined on the growth of four taro landraces Dumbe-dumbe, Mgingqeni, Pitshi and Dumbe-lomfula. Pitshi-omhlophe, an ecotype of Pitshi for which there was a limited amount of planting material, was also included in the glasshouse studies. The farmers stated that the normal growing season for the economically important landraces, Dumbe-dumbe and Mgingqeni, was six months, but in this study plants were grown in glasshouses for nine months, and in the field, for seven months before the attainment of harvest maturity. Emergence was determined daily for glasshouse experiment until all plants had emerged and it was determined monthly for the field experiment. Leaf number, plant height and leaf area were measured every month to determine growth and development, while number of corms and fresh corm weight were used at harvest to determine yield. For all landraces, time to emergence increased significantly with decrease in temperature from 33/23°C to 27/17°C, but it increased significantly for only Dumbe-dumbe and Mgingqeni from 27/17°C to 22/12°C. Mgingqeni showed the shortest time to emergence, whereas, Pitshi showed the longest delay in emergence. The locations were not significantly different in emergence. Mgingqeni displayed the highest emergence in UKZN (91.4%), whereas, Dumbe-dumbe displayed the highest emergence (95.5%) and Dumbe-lomfula displayed the lowest emergence (55.9%) in Umbumbulu. Leaf number was highest for Pitshi-omhlophe, in glasshouse experiment due to its tendency to produce multiple shoots compared with the other landraces. Plant height increased with increase in temperature for all landraces except for Pitshi, for which height decreased with an increase in temperature. Leaf area was greatest for Dumbe-lomfula at all temperatures and lowest for Pitshi at both 22/12°C and 27/17°C. Leaf number was highest for Mgingqeni and lowest for Dumbe-lomfula at both sites, although it was significantly lower only for Dumbe-lomfula in UKZN. Plant height and leaf area were significantly highest for Dumbe-lomfula at both sites. The highest total number of corms per plant was shown by Pitshi-omhlophe at 22/12°C. Total fresh corm weight was highest for Dumbe-lomfula at 27/17°C and lowest for Pitshi at 22/22°C. The field experiment results showed Pitshi and Dumbe-lomfula with significantly higher total fresh corm weight in UKZN compared with Umbumbulu. Corms were analysed for mineral elements and starch. There were significant differences in starch content between temperatures (P = 0.017) and taro landraces (P = 0.025). There was also a significant interaction of temperatures and landrace (P = 0.002). Starch content increased with temperature for all landraces except for Pitshi-omhlophe and Dumbe-lomfula which showed a decrease at 27/17°C. There were significant differences in corm mineral content between temperatures, locations and landraces (P < 005). It is concluded that the chemical composition of taro corms is influenced by growth temperature and the location (site) where the crop is grown. The results of this study also indicated that taro plant growth is enhanced by high temperatures (33/23°C). High temperatures are, however, associated with short leaf area duration and subsequently low yield. The findings of this study may also be useful in determining taro quality for processing.<br>Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.