Cowpea (Vigna unguiculata. L) is an important African crop. However, it is also an underutilized grain legume. Consequently, there is not enough research data on cowpea seed physiology. Whereas there is evidence of cowpea being a drought tolerant crop, there is no evidence to associate plant drought tolerance with seed quality in response to water stress. This study sought to understand the effect of production site and water stress on cowpea seed quality development with respect to germination capacity and vigour. Patterns of raffinose family of oligosaccharides (RFO) during seed development to mature dry stage were used to physiologically relate seed performance to water stress. The effect of water stress and exogenous ABA on the accumulation of stress LEA proteins (dehydrins) in relation to seed quality development and germination was investigated. RFOs are known for their roles in desiccation sensitivity but no studies have shown their significance in cowpeas. Seeds of six cowpea cultivars were produced at two distinct growth sites characterised by irrigated and dry land conditions. The seeds were assessed during six developmental stages, for water content, dry matter accumulation, and performance. Harvested seeds were then planted in a pot experiment under controlled conditions to examine the effect of water stress on seed quality development and data collected during three developmental stages. Harvested seeds from the pot experiment were subsequently analyzed for changes in RFO accumulation during development using gas chromatography. The seeds were also used to investigate the effect of water stress and ABA on the accumulation of stress LEA proteins (dehydrins) in relation to seed quality development in cowpea. In addition, this study evaluated the use of image analysis as a method that can be used to objectively determine seed coat colour variation in cowpea. Statistical variation in individual seed’s solute leakage for cowpea cultivars differing in seed coat colour and produced under different environmental conditions was explored and correlations were done between seed conductivity test with other aspects of seed performance during germination. Furthermore the results of the conductivity test were compared with accelerated aging test, in relation to seed performance. The study provided evidence that cowpea seed lots produced under different environmental, and possibly management conditions may not differ with respect to seed quality as determined by germination capacity and vigour. However, significant differences between sites with respect to seed maturation patterns determined by water content and dry matter accumulation were observed. Adverse maternal environmental effects on the subsequent performance of seeds in a drought tolerant crop may not necessarily lead to poor performance. Cultivar differences in response to simulated drought conditions at the whole plant and tissue level can be considerable and highly variable; however, these differences may not have adverse effects on the germination and vigour of the seeds. Drought avoidance mechanisms at the whole plant level in cowpea are quite efficient in allowing the species to adapt to simulated drought conditions. These mechanisms may allow the cowpea cultivars to maintain metabolism and restore conditions for their continued growth under water stress; and produce few seeds of high germination capacity and vigour. Stachyose was found to be the predominant member of the raffinose family of oligosaccharides in cowpea. It is suggested that stachyose accumulation could be used as an indicator of stress tolerance in cowpea. However, the relationship between RFO concentration and the acquisition of desiccation remained as a matter of speculation in the present study and is still generally inconclusive. There was no evidence to suggest the acquisition of maximum desiccation tolerance is associated with maximum seed vigour. It is suggested in cowpea, which is drought tolerant, that maximum vigour does not necessarily imply the acquisition of maximum desiccation tolerance; rather there is a minimum level of desiccation tolerance that is required for the development of optimal seed vigour. The use of an in vivo approach in the study of LEA function in cowpea enabled the accurate comparison of two different groups of LEA proteins in developing cowpea seeds under conditions of water stress and in relation to germination and vigour. Both group 1 LEA and group 2 LEA (dehydrin) were shown to increase in concentration in response to water stress. In addition group 1 LEA protein was observed to be relatively abundant in cowpea seeds. A maternal influence on LEA protein gene expression under conditions of water stress, which may induce dehydrin accumulation vii during the earlier stages of seed development, was implied by the observation that dehydrin-like proteins were induced after two weeks of development in cowpea plants subjected to stress during the vegetative phase. In addition, the exogenous application of ABA delayed radicle protrusion; this was associated with a delay in the disappearance of LEA proteins and is suggestive of a relationship between LEA protein accumulation and the acquisition of desiccation tolerance. The study has demonstrated that image analysis can objectively discriminate seed coat colour variation in cowpea. Dark coloured seeds in general performed better than light coloured seeds; however seed coat colour was not always associated with better performance. A newly developed Aging Stress Differential Index (ASDI) has been used in this study to demonstrate a link between seed coat colour and sensitivity to water stress. The ASDI correlated well with the observations relating stress tolerance to stachyose accumulation. The skewed distribution patterns in individual electrical conductivity and the presence of extreme values may have implications with respect to the suitability of using standard statistical analyses which compare mean values to evaluate such data. In addition variation in individual electrical conductivity may also be influenced by cultivar differences and the chemical composition of the seed coat. Therefore associations between seed coat colour and electrical conductivity as a measure of performance should be treated with caution. The AA test does reflect changes in seed vigour, however ranked electrical conductivity values after AA did not consistently reflect differences in seed performance between cultivars and sites, and they did not correlate well with other aspects of performance. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Bambara groundnut is a protein-rich legume, with food security potential in drought-prone regions. It has been grown for many centuries and has remained an important crop to most African subsistence farmers. However, despite its high nutritional status and yield advantages in poor soils, it remains one of the neglected crops by science. There have now been recent efforts to study underutilised crops, with the aim of promoting them as healthy alternatives for people facing resource and environmental challenges and to contribute to food security. In order to do this, there needs to be information that can be used to advise farmers on the agronomic aspects of producing the crop. The overall aim of the study was to evaluate the response of bambara groundnut landraces to drought under controlled environment and field conditions. Seeds were initially collected from subsistence farmers in Jozini, KwaZulu-Natal, and characterised into three seed lots distinguished by seed coat colour: red, white and brown. In the initial study (Chapter 2) seed quality of bambara groundnuts was evaluated. Seed lots were used for standard germination (SG) and cold test (CT). Seeds were germinated under two conditions, 25°C for 8 days (SG) and 4°C for 7 days followed by 8 days at 25°C (CT). Germination percentage, seedling size and mass were determined. Desiccation tolerance was evaluated by suspending 30 seeds of each seed lot over saturated salt solutions of NaCl, LiCl, KNO3 and H2O (control) for 0, 2, 4, 8, 24 and 48 hours. Five seeds were sampled at each interval and stored at -21°C for 7 days. Samples were ground and analysed for proline content. In addition, early establishment performance of bambara groundnut was evaluated under controlled environment conditions in seedling trays using two water regimes (Chapter 2). The experimental design had three factors: seed lot (colour), priming (NaCl, LiCl, KNO3, H2O and control) and water regimes [25% and 75% Field Capacity (F.C.)]. The experiment was replicated three times. Seedling emergence was determined daily for 21 days. Seedling height and leaf number were determined weekly for three weeks, thereafter, seedling leaf area, root and shoot mass (fresh and dry), root and shoot lengths and root to shoot ratio were also determined. Seedlings were later transplanted in 90 pots for a pot trial in order to evaluate growth responses of bambara groundnut to water stress; plant height, leaf number and yield components were determined (Chapter 3). Lastly, the use of planting date selection as a management strategy for managing the occurrence of water stress under field conditions was evaluated in field trials. The experimental design was a split-split-plot design with planting date as main factor (early, optimum and late), irrigation and rainfed as sub-main factor, and seed colour as sub-plots (brown, red and white) arranged in a randomised complete block design (RCBD), with three replications. There were three planting dates: 7 September (early planting), 24 November (optimum planting) and 19 January (late planting). Results from Chapter 2 showed that the brown seed lot had the highest germination across treatments, followed by red and white seeds, respectively. There were significant differences between seed lots (P < 0.05) and salt solutions (P < 0.05) with respect to proline content. Seed proline content increased from 0 to 8 hours and later declined; NaCl was associated with the highest proline accumulation. There were highly significant differences (P < 0.001) between seed colours, priming treatments and F.C., as well as their interaction, with respect to seedling emergence. White seeds had the highest emergence, followed by brown and red, respectively. Priming seeds improved their emergence compared to the control, with highest emergence being observed in seeds treated with LiCl. Priming also improved emergence under water stress; 25% F.C. had the highest emergence compared to 75% F.C. Results from Chapter 3 showed that, seeds primed with NaCl and KNO3 resulted in tallest plants with the highest number of leaves per plant. However, NaCl and KNO3 were also the most affected under water stress. Priming was shown to improve germination and early crop establishment of bambara groundnut landraces under water stress. However, yield per plant did not improve in response to either halo- or hydro-priming. Results from field trials showed that in terms of the measured plant growth parameters (plant height, leaf number and LAI), bambara groundnut landraces were sensitive water stress. Water stress decreased yield components, and hence yield. However, selection of planting dates was shown to be a useful management tool for managing water stress under water limited field conditions. Choice of planting date significantly affected both plant growth and yield. The optimum planting date resulted in the best crop growth for all measured plant growth parameters followed by late and early planting dates, respectively. Seed quality was shown to be associated with seed lot colour. Darker coloured (red and brown) seeds performed better than light (white) seeds with respect to germination. Priming was also shown to improve germination and early crop establishment of bambara groundnut landraces under water stress. However, yield per plant did not improve following priming. Growth of bambara groundnut landraces was shown to be sensitive to water stress. Water stress decreased yield components and hence yield under both controlled and field conditions. Choice of planting date significantly affected both plant growth and yield. The optimum planting date was shown to be the best performing planting date. The findings of this study suggest that bambara groundnut seed performance in terms of germination, stand establishment and productivity is associated with seed lot colour. Seed priming improves seed performance and enhances crop capacity to withstand water stress. If the optimum planting date for groundnuts (late spring to early summer) is missed, better crop performance and yield are obtained from late planting (late summer to early spring) compared with early planting (early spring). Bambara groundnut has a potential for production under water stress conditions in controlled and field environments. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

The Eastern Cape Province of South Africa has climatic conditions which differ from region to region. The groundnut (Arachis hypogaea L.) cultivars, as it is the case with other crops, do not always perform equally well in the varying conditions. Abiotic stresses such as drought, extreme temperatures, and high soil acidity restrict plant growth. Lack of studies on adaptability of commercial groundnut cultivars in the Eastern Cape necessitated this study. Abiotic and biotic factors are not the only limiting factors: calcium availability in the soil is also a limiting factor in groundnut production. The aim of the study was to identify best suited cultivars for climatic conditions of Mthatha and Lusikisiki regions of the Eastern Cape. Two similar field experiments were conducted in the two locations with different climatic conditions. The results showed significant differences (P<0.05) in genotypes with respect to seed yield in both locations. Kwarts produced higher seed yield of 1155 kg ha-1 in Mthatha, while the same genotype produced low seed yield of 630 kg ha-1 in Lusikisiki location. In Lusikisiki the highest seed yield was recorded in Anel (936 kg ha-1) which produced low yield of 692 kg ha-1 in Mthatha. The genotypes that performed well in Mthatha in 2010/11 season included Kwarts, Nyanda, ICGV-SM 95714 and Mwenje. These genotypes were further used to investigate their response to calcium supplementation at flowering stage under conditions of Mthatha in the 2011/12 season. The results were significantly different for calcium absorption (P<0.05). Nyanda, Kwarts and Mwenje responded positively to calcium application at flowering stage producing relatively high yield of 153, 150 and 110 kg ha-1, respectively. Oil content was significantly increased by calcium application at flowering in Nyanda with 27.28% compared to 20.7% without Ca.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Soybeans are the main oilseed grown in the world, and among the factors that hinder the production of high-quality soybeans, is the frequent rainfall during periods of maturation and preharvest. Characteristics of seeds as the seed coat lignin content may reflect a greater or lesser susceptibility to deterioration from humidity and mechanical damage. Thus, although there are data and evidence that the lignin content confers resistance to deterioration from humidity, there is a lack of experiments with methods which are similar to the adverse weather conditions that the seeds remain exposed in the field. Therefore, this study was developed in order to evaluate the relationship between the lignin content of soybean seed coat, with tolerance to deterioration from humidity and mechanical damage. The work primarily consists of a brief literature review, Chapter I, and two more chapters. Chapter II contains the work that evaluates the relationship between seed coat lignin content of soybean seeds with tolerance to deterioration from humidity and mechanical damage. Chapter III, to qualify the experiments in the area, is aimed to estimate the ideal sample size, in number of seeds required for the tetrazolium test for soybean seeds. The CD 208 and CD 215 cultivars, with higher lignin content in seed coat, 4.19% and 2.64%, respectively, had higher vigor after stress with simulated rainfall. Furthermore, the cultivar CD 208, was also less susceptible to damage from humidity and mechanical damage. Oxidative stress in shoots and roots of the seedlings was demonstrated by the enzyme peroxidase activity Guaiacol, which increased the cultivars CD 215, CD 202 and BRS 184, with lower lignin content in seed coat than 3%. About the seeds, the cultivar BRS 184 with lower lignin content, 1.69%, showed a higher oxidative stress due to increased activity of the enzyme Guaiacol Peroxidase and lipid peroxidation. The sample size in number of seeds, to assess humidity damage through the tetrazolium test in soybean seeds is dependent on the physiological quality of cultivars, recommending to the highest level of precision 200 seeds per lot, and for a below level and acceptable accuracy, 0.5% CI, 121 seeds. / A soja é a principal aleuro-oleaginosa cultivada no mundo, e entre os fatores que dificultam a produção de sementes de soja de elevada qualidade, está a ocorrência frequente de chuvas durante os períodos de maturação e pré-colheita. Características das sementes, tal como, o conteúdo de lignina do tegumento, podem refletir em maior ou menor suscetibilidade à deterioração por umidade e dano mecânico. Assim, embora existam dados e evidências de que o teor de lignina confere resistência à deterioração por umidade, faltam experimentos com metodologias as quais se assemelhem com as condições climáticas adversas que as sementes permanecem expostas em campo. Diante disso, desenvolveu-se esse estudou com o objetivo de avaliar a relação entre o conteúdo de lignina do tegumento da semente de soja, com a tolerância à deterioração por umidade e dano mecânico. O trabalho consiste primeiramente de uma breve revisão bibliográfica, capítulo I, e de mais dois capítulos. O capítulo II consta do trabalho que tem por objetivo avaliar a relação entre o conteúdo de lignina do tegumento das sementes de soja, com a tolerância à deterioração por umidade e dano mecânico. O capítulo III, para qualificar os experimentos da área, objetivou-se estimar o tamanho ideal de amostra, em número de sementes, necessário para o teste de tetrazólio, em sementes de soja com elevado dano por umidade. As cultivares CD 208 e CD 215, com os maiores teores de lignina no tegumento, 4,19% e 2,64%, respectivamente, apresentaram maior vigor após o estresse com a chuva simulada. Além disso, a cultivar CD 208, também se mostrou menos suscetível ao dano por umidade e ao dano mecânico. O estresse oxidativo na parte aérea e raízes das plântulas foi demonstrado através da atividade da enzima Guaiacol Peroxidase, o qual aumentou nas cultivares CD 215, CD 202 e BRS 184, com teores de lignina no tegumento menor que 3%. Já nas sementes, a cultivar BRS 184, com menor teor de lignina, 1,69%, apresentou um maior estresse oxidativo devido a maior atividade da enzima Guaiacol Peroxidase e da peroxidação lipídica. O tamanho de amostra em número de sementes, para avaliar os danos por umidade por meio do teste de tetrazólio em sementes de soja é dependente da qualidade fisiológica das cultivares, recomendando-se para o maior nível de precisão 200 sementes por lote, e para um nível menor, porém aceitável, de precisão, 0,5% de IC, 121 sementes.

CAPES; Fundação Araucária / No cenário nacional, a cultura da soja ocupa posição de destaque quanto à área plantada e ao volume de produção, sendo cultivada em grande parte no sistema de plantio direto. Esse sistema, devido ao intenso tráfego de máquinas e implementos na sua superfície tem acarretado problemas de compactação do solo, que tem ocasionado a queda de rendimento das culturas. A fim de minimizar este efeito as semeadoras-adubadoras utilizam os sistemas de abertura de sulco do tipo disco duplo ou haste sulcadora. O uso da haste passou a ser corriqueira por permitir o rompimento da camada superficial compactada, porém necessita de uma maior demanda energética, podendo causar excesso de mobilização do solo nas áreas onde não se observam elevados níveis de compactação. Assim, este trabalho teve como objetivo avaliar os efeitos de mecanismos sulcadores e níveis de compactação do solo na demanda de tração solicitada por uma semeadora-adubadora, no desenvolvimento e produtividade da cultura da soja, cultivada em um Latossolo Vermelho de textura argilosa, no período de duas safras agrícolas. Foi utilizado o delineamento em blocos ao acaso com parcelas subdivididas, sendo as parcelas principais compostas por quatro níveis de compactação do solo (N0 – Plantio Direto sem compactação adicional; N1, N2 e N3 – Plantio Direto submetido à compactação adicional, por meio de duas, quatro e seis passadas com trator, respectivamente) correspondendo as densidades do solo de 1,16, 1,20, 1,22 e 1,26 g cm-3, e as subparcelas por dois mecanismos sulcadores (haste sulcadora e disco duplo), com quatro repetições. Para avaliar a força de tração média, máxima e específica solicitada pela semeadora foi utilizada uma célula de carga, com capacidade de 50 kN e sensibilidade de 2 mV V-1, acoplada entre o trator e a semeadora, cujos dados foram armazenados em um sistema de aquisição de dados modelo CR800 da Campbell Scientific. Foram avaliados ainda a resistência do solo à penetração, profundidade de semeadura, profundidade e largura de sulco, área de solo mobilizada, índice de velocidade de emergência, marcha de emergência, estande final de plantas, diâmetro de colmo, altura de plantas, número médio de grãos por vagem, massa de 1.000 grãos, número de vagens por planta e produtividade da cultura. Os dados foram submetidos à análise de variância, as médias dos sulcadores foram comparadas pelo teste de Tukey (p≤0,05), enquanto que para o fator compactação do solo, foi adotada a análise de regressão polinomial, sendo os modelos selecionados, pelo critério de maior R2 e a significância (p≤0,05) dos parâmetros da equação. Independente do ano agrícola estudado, a resistência à penetração aumentou como os níveis de compactação do solo até em torno de 0,20 m de profundidade, e a densidade do solo influenciou os parâmetros de qualidade de semeadura, porém, não afetou a produtividade da cultura. Na primeira safra, foi observado maior produtividade com o uso do sulcador tipo haste. Na segunda safra, a haste sulcadora exigiu maior demanda energética com o aumento de densidade do solo e situação inversa com o disco duplo. O travamento das linhas de semeadura, possibilitou melhor desempenho da haste sulcadora em quebrar a camada compactada. / On the national scene, soybean crop occupies a prominent position in cultivated area and volume production, being cultivated largely in the no tillage system. This system, due to the intense traffic of machines and implements on its surface has caused soil compaction problems, which has caused the yield loss of crops. In order to minimize this effect the seeder-drill uses the systems to opening the furrow by shank or the double disc type. The use of the shank has become commonplace for allowing the disruption of the compacted surface layer, however requires greater energy demand and may cause excessive tillage in areas where there is not observed high levels of compaction. Thus, this study aimed to evaluate the effects of furrowers mechanisms and levels of soil compacting on traction requirement by a seeder-drill and on the growing and productivity of soybean in an Oxisol texture clay, in a two growing seasons. The experimental design consisted of randomized blocks with split plots with the main plots composed of four levels of soil compaction (N0 – no tillage without additional compaction, N1, N2 and N3 – no tillage subjected to compaction through two, four and six passes with tractor, respectively) corresponding to densities of soil 1.16, 1.20, 1.22 and 1.26 g cm-3, and subplots by two furrowers mechanisms (shank and double disc) with four replicates. To evaluate the average, maximum and specific traction force requested by the seeder-drill, was used a load cell, with capacity of 50 kN and sensitivity of 2 mV V-1, coupled between the tractor and seeder-drill, whose data are stored in a datalogger system model CR800 of Campbell Scientific. In addition, were evaluated the bulk density, soil mechanical resistance to penetration, sowing depth, depth and groove width, soil area mobilized, emergence speed index, emergence operation, final plant stand, stem diameter, plant height, average number of seeds per pod, weight of 1,000 seeds, number of pods per plant and crop productivity. Data were subjected to analysis of variance, the mean of furrowers were compared by Tukey test (p≤0.05), while for the factor soil compaction, polynomial regression analysis was adopted, selected models by the criterion of greater R2 and significance (p≤0.05) of equation parameters. Regardless of the crop season, penetration resistance increase as soil compaction levels up to around 0.20 m deep, and bulk density influenced the sowing quality parameters, however, did not affect the crop yield. In the first season, there was a higher productivity with the use of the shank type. In the second crop season, the shank demanded greater energetic requirement with the increase of bulk density and opposite situation with the double disc. The locking of sowing lines allow better performance of the shank to break the compacted layer.

O milho (Zea mays L.) é um dos cereais mais cultivados no mundo e apresenta papel importante na economia mundial. Com a expansão do plantio da cultura, reduziu-se o convívio harmônico entre a cutlura e as doenças, aumentando com isso, os danos causados, principalmente por fungos fitopatogênicos. Sabendo-se destas necessidades, foram realizados dois estudos que envolveram o uso de fosfitos isolados e, associados com fungicidas comerciais recomendados para o tratamento de sementes. Objetivou-se avaliar o potencial dos fosfitos sobre Fusarium verticilliodes e Fusarium graminearum em condições in vitro e em in vivo sobre a sanidade e qualidade fisiológica das sementes e uma possível ativação do metabolismo de defesa das plantulas. Para o primeiro estudo, foi realizado um experimento in vitro, objetivando avaliar o efeito dos fosfitos, nas doses correspondentes à 0; 0,2; 0,4; 0,6; 0,8; e 1mL/1,0 Kg de sementes. Os fosfitos foram depositados em meio de cultura vertidos em meio BDA, ajustando-se o pH para 5,6. Em placas de Petri, foram dispostos discos de micélio de 7 mm dos fungos F. verticilliodes e F. graminearum. As placas foram incubadas em temperatura de 24 + ou – 1ºC com fotoperíodo de 12 horas luz/escuro. Então, avaliou-se o crescimento micelial em resposta aos tratamentos. Ainda, nesse estudo avaliou-se a sanidade de sementes de milho, tratadas com misturas de fosfitos e fungicidas comerciais. Para o tratamento das sementes, usou-se os fungicidas carbendazim + thiram, fludioxonil + metalaxyl−m em associação com fertilizantes a base de fosfito de potássio, de cobre, complexo nutricional e complexo potencializador, nas doses de 1,5; 3,0; 1; 1; 2 e 3 mL/1 Kg de sementes respectivamente. Para o segundo estudo, os fertilizantes a base de fosfitos de potássio e de cobre foram associados aos fungicidas comerciais carbendazim + thiram, fludioxonil + metalaxyl−m, para avaliar os seus efeitos sobre o desempenho fisiológico das sementes e identificar as possíveis rotas metabólicas envolvidas no processo de defesa vegetal. Foram quantificadas a viabilidade, por meio do teste de germinação e o vigor, submetendo-se as sementes aos testes de envelhecimento acelerado, teste de frio, comprimento e materia seca de plântulas e emergencia em campo, calculando-se o indice de velocidade de emergência, velocidade de emergência e coeficiente de velocidade de emergência. O material vegetal, foi coletado e realizadas as análises bioquímicas de proteínas totais, e atividade das enzimas fenilalanina amônialiase, quitinase e β 1,3 glucanase. O crescimento micelial in vitro dos dois fungos foi afetado pelos tratamentos à base de fosfitos. Ocorreu maior supressão micelial com o fosfito de potássio e fosfito de manganês. Verificou-se que o melhor estado sanitário das sementes foi obtido quando utilizou-se a mistura de carbendazim + thiram e fosfito de potássio. O efeito dos fosfitos de potássio e cobre no tratamento de sementes de milho, associados a fungicidas incrementaram o seu potencial fisiológico. Os tratamentos não interferiram na ativação da rota dos fenilpropanóides e na síntese das enzimas quitinase e β 1,3 glucanase, quando utilizados para o tratamento de sementes de milho. / Corn (Zea mays L.) is one of the most cultivated cereals in the world and plays an important role in the world economy. With the expansion of planting of the culture, the harmonic conviviality between the cutlura and the diseases was reduced, increasing with this, the damages caused, mainly by phytopathogenic fungi. Knowing these needs, two studies were carried out that involved the use of isolated phosphites and, associated with commercial fungicides recommended for the treatment of seeds. The objective of this study was to evaluate the potential of phosphites on Fusarium verticilliodes and Fusarium graminearum in in vitro and in vivo conditions on the physiological quality and health of the seeds and a possible activation of the seedling defense metabolism. For the first study, an in vitro experiment was carried out to evaluate the effect of the phosphites at the doses corresponding to 0; 0.2; 0.4; 0.6; 0.8; And 1mL / 1.0 Kg of seeds. The phosphites were deposited in culture medium poured into BDA medium, adjusting the pH to 5.6. In Petri dishes, 7 mm mycelium discs of the fungi F. verticilliodes and F. graminearum were arranged. The plates were incubated at a temperature of 24 ± 1 ° C in a 12-hour light / dark photoperiod. Then, the mycelial growth in response to the treatments was evaluated. Also, in this study, the sanity of maize seeds, treated with mixtures of commercial phosphites and fungicides, was evaluated. For the treatment of the seeds, the fungicides carbendazim + thiram, fludioxonil + metalaxyl-m were used in association with fertilizers based on potassium phosphite, copper, nutritional complex and potentiating complex, at doses of 1,5; 3.0; 1; 1; 2 and 3 mL / 1 Kg of seeds respectively. For the second study, fertilizers based on potassium and copper phosphites were associated with the commercial fungicides carbendazim + thiram, fludioxonil + metalaxyl-m, to evaluate their effects on the physiological performance of the seeds and to identify the possible metabolic routes involved in the Process of plant defense. The viability, through the germination test and the vigor, were quantified by subjecting the seeds to the tests of accelerated aging, cold test, seedling length and dry matter and field emergence, calculating the rate of emergency, emergency speed and emergency speed coefficient. Plant material, was collected and performed the biochemical analyzes of total proteins, and activity of the enzymes phenylalanine ammonia lyase, chitinase and β-1,3 glucanase. In vitro mycelial growth of the two fungi was affected by the phosphite treatments. Mycelial suppression occurred with potassium phosphite and manganese phosphite. It was found that the best sanitary condition of the seeds was obtained when the mixture of carbendazim + thiram and potassium phosphite was used. The effect of potassium and copper phosphites on corn seed treatment associated with fungicides increased their physiological potential. The treatments did not interfere in the activation of the phenylpropanoic route and in the synthesis of the enzymes chitinase and β-1,3 glucanase when used for the treatment of corn seeds.

CAPES; Fundação Araucária / No cenário nacional, a cultura da soja ocupa posição de destaque quanto à área plantada e ao volume de produção, sendo cultivada em grande parte no sistema de plantio direto. Esse sistema, devido ao intenso tráfego de máquinas e implementos na sua superfície tem acarretado problemas de compactação do solo, que tem ocasionado a queda de rendimento das culturas. A fim de minimizar este efeito as semeadoras-adubadoras utilizam os sistemas de abertura de sulco do tipo disco duplo ou haste sulcadora. O uso da haste passou a ser corriqueira por permitir o rompimento da camada superficial compactada, porém necessita de uma maior demanda energética, podendo causar excesso de mobilização do solo nas áreas onde não se observam elevados níveis de compactação. Assim, este trabalho teve como objetivo avaliar os efeitos de mecanismos sulcadores e níveis de compactação do solo na demanda de tração solicitada por uma semeadora-adubadora, no desenvolvimento e produtividade da cultura da soja, cultivada em um Latossolo Vermelho de textura argilosa, no período de duas safras agrícolas. Foi utilizado o delineamento em blocos ao acaso com parcelas subdivididas, sendo as parcelas principais compostas por quatro níveis de compactação do solo (N0 – Plantio Direto sem compactação adicional; N1, N2 e N3 – Plantio Direto submetido à compactação adicional, por meio de duas, quatro e seis passadas com trator, respectivamente) correspondendo as densidades do solo de 1,16, 1,20, 1,22 e 1,26 g cm-3, e as subparcelas por dois mecanismos sulcadores (haste sulcadora e disco duplo), com quatro repetições. Para avaliar a força de tração média, máxima e específica solicitada pela semeadora foi utilizada uma célula de carga, com capacidade de 50 kN e sensibilidade de 2 mV V-1, acoplada entre o trator e a semeadora, cujos dados foram armazenados em um sistema de aquisição de dados modelo CR800 da Campbell Scientific. Foram avaliados ainda a resistência do solo à penetração, profundidade de semeadura, profundidade e largura de sulco, área de solo mobilizada, índice de velocidade de emergência, marcha de emergência, estande final de plantas, diâmetro de colmo, altura de plantas, número médio de grãos por vagem, massa de 1.000 grãos, número de vagens por planta e produtividade da cultura. Os dados foram submetidos à análise de variância, as médias dos sulcadores foram comparadas pelo teste de Tukey (p≤0,05), enquanto que para o fator compactação do solo, foi adotada a análise de regressão polinomial, sendo os modelos selecionados, pelo critério de maior R2 e a significância (p≤0,05) dos parâmetros da equação. Independente do ano agrícola estudado, a resistência à penetração aumentou como os níveis de compactação do solo até em torno de 0,20 m de profundidade, e a densidade do solo influenciou os parâmetros de qualidade de semeadura, porém, não afetou a produtividade da cultura. Na primeira safra, foi observado maior produtividade com o uso do sulcador tipo haste. Na segunda safra, a haste sulcadora exigiu maior demanda energética com o aumento de densidade do solo e situação inversa com o disco duplo. O travamento das linhas de semeadura, possibilitou melhor desempenho da haste sulcadora em quebrar a camada compactada. / On the national scene, soybean crop occupies a prominent position in cultivated area and volume production, being cultivated largely in the no tillage system. This system, due to the intense traffic of machines and implements on its surface has caused soil compaction problems, which has caused the yield loss of crops. In order to minimize this effect the seeder-drill uses the systems to opening the furrow by shank or the double disc type. The use of the shank has become commonplace for allowing the disruption of the compacted surface layer, however requires greater energy demand and may cause excessive tillage in areas where there is not observed high levels of compaction. Thus, this study aimed to evaluate the effects of furrowers mechanisms and levels of soil compacting on traction requirement by a seeder-drill and on the growing and productivity of soybean in an Oxisol texture clay, in a two growing seasons. The experimental design consisted of randomized blocks with split plots with the main plots composed of four levels of soil compaction (N0 – no tillage without additional compaction, N1, N2 and N3 – no tillage subjected to compaction through two, four and six passes with tractor, respectively) corresponding to densities of soil 1.16, 1.20, 1.22 and 1.26 g cm-3, and subplots by two furrowers mechanisms (shank and double disc) with four replicates. To evaluate the average, maximum and specific traction force requested by the seeder-drill, was used a load cell, with capacity of 50 kN and sensitivity of 2 mV V-1, coupled between the tractor and seeder-drill, whose data are stored in a datalogger system model CR800 of Campbell Scientific. In addition, were evaluated the bulk density, soil mechanical resistance to penetration, sowing depth, depth and groove width, soil area mobilized, emergence speed index, emergence operation, final plant stand, stem diameter, plant height, average number of seeds per pod, weight of 1,000 seeds, number of pods per plant and crop productivity. Data were subjected to analysis of variance, the mean of furrowers were compared by Tukey test (p≤0.05), while for the factor soil compaction, polynomial regression analysis was adopted, selected models by the criterion of greater R2 and significance (p≤0.05) of equation parameters. Regardless of the crop season, penetration resistance increase as soil compaction levels up to around 0.20 m deep, and bulk density influenced the sowing quality parameters, however, did not affect the crop yield. In the first season, there was a higher productivity with the use of the shank type. In the second crop season, the shank demanded greater energetic requirement with the increase of bulk density and opposite situation with the double disc. The locking of sowing lines allow better performance of the shank to break the compacted layer.

O milho (Zea mays L.) é um dos cereais mais cultivados no mundo e apresenta papel importante na economia mundial. Com a expansão do plantio da cultura, reduziu-se o convívio harmônico entre a cutlura e as doenças, aumentando com isso, os danos causados, principalmente por fungos fitopatogênicos. Sabendo-se destas necessidades, foram realizados dois estudos que envolveram o uso de fosfitos isolados e, associados com fungicidas comerciais recomendados para o tratamento de sementes. Objetivou-se avaliar o potencial dos fosfitos sobre Fusarium verticilliodes e Fusarium graminearum em condições in vitro e em in vivo sobre a sanidade e qualidade fisiológica das sementes e uma possível ativação do metabolismo de defesa das plantulas. Para o primeiro estudo, foi realizado um experimento in vitro, objetivando avaliar o efeito dos fosfitos, nas doses correspondentes à 0; 0,2; 0,4; 0,6; 0,8; e 1mL/1,0 Kg de sementes. Os fosfitos foram depositados em meio de cultura vertidos em meio BDA, ajustando-se o pH para 5,6. Em placas de Petri, foram dispostos discos de micélio de 7 mm dos fungos F. verticilliodes e F. graminearum. As placas foram incubadas em temperatura de 24 + ou – 1ºC com fotoperíodo de 12 horas luz/escuro. Então, avaliou-se o crescimento micelial em resposta aos tratamentos. Ainda, nesse estudo avaliou-se a sanidade de sementes de milho, tratadas com misturas de fosfitos e fungicidas comerciais. Para o tratamento das sementes, usou-se os fungicidas carbendazim + thiram, fludioxonil + metalaxyl−m em associação com fertilizantes a base de fosfito de potássio, de cobre, complexo nutricional e complexo potencializador, nas doses de 1,5; 3,0; 1; 1; 2 e 3 mL/1 Kg de sementes respectivamente. Para o segundo estudo, os fertilizantes a base de fosfitos de potássio e de cobre foram associados aos fungicidas comerciais carbendazim + thiram, fludioxonil + metalaxyl−m, para avaliar os seus efeitos sobre o desempenho fisiológico das sementes e identificar as possíveis rotas metabólicas envolvidas no processo de defesa vegetal. Foram quantificadas a viabilidade, por meio do teste de germinação e o vigor, submetendo-se as sementes aos testes de envelhecimento acelerado, teste de frio, comprimento e materia seca de plântulas e emergencia em campo, calculando-se o indice de velocidade de emergência, velocidade de emergência e coeficiente de velocidade de emergência. O material vegetal, foi coletado e realizadas as análises bioquímicas de proteínas totais, e atividade das enzimas fenilalanina amônialiase, quitinase e β 1,3 glucanase. O crescimento micelial in vitro dos dois fungos foi afetado pelos tratamentos à base de fosfitos. Ocorreu maior supressão micelial com o fosfito de potássio e fosfito de manganês. Verificou-se que o melhor estado sanitário das sementes foi obtido quando utilizou-se a mistura de carbendazim + thiram e fosfito de potássio. O efeito dos fosfitos de potássio e cobre no tratamento de sementes de milho, associados a fungicidas incrementaram o seu potencial fisiológico. Os tratamentos não interferiram na ativação da rota dos fenilpropanóides e na síntese das enzimas quitinase e β 1,3 glucanase, quando utilizados para o tratamento de sementes de milho. / Corn (Zea mays L.) is one of the most cultivated cereals in the world and plays an important role in the world economy. With the expansion of planting of the culture, the harmonic conviviality between the cutlura and the diseases was reduced, increasing with this, the damages caused, mainly by phytopathogenic fungi. Knowing these needs, two studies were carried out that involved the use of isolated phosphites and, associated with commercial fungicides recommended for the treatment of seeds. The objective of this study was to evaluate the potential of phosphites on Fusarium verticilliodes and Fusarium graminearum in in vitro and in vivo conditions on the physiological quality and health of the seeds and a possible activation of the seedling defense metabolism. For the first study, an in vitro experiment was carried out to evaluate the effect of the phosphites at the doses corresponding to 0; 0.2; 0.4; 0.6; 0.8; And 1mL / 1.0 Kg of seeds. The phosphites were deposited in culture medium poured into BDA medium, adjusting the pH to 5.6. In Petri dishes, 7 mm mycelium discs of the fungi F. verticilliodes and F. graminearum were arranged. The plates were incubated at a temperature of 24 ± 1 ° C in a 12-hour light / dark photoperiod. Then, the mycelial growth in response to the treatments was evaluated. Also, in this study, the sanity of maize seeds, treated with mixtures of commercial phosphites and fungicides, was evaluated. For the treatment of the seeds, the fungicides carbendazim + thiram, fludioxonil + metalaxyl-m were used in association with fertilizers based on potassium phosphite, copper, nutritional complex and potentiating complex, at doses of 1,5; 3.0; 1; 1; 2 and 3 mL / 1 Kg of seeds respectively. For the second study, fertilizers based on potassium and copper phosphites were associated with the commercial fungicides carbendazim + thiram, fludioxonil + metalaxyl-m, to evaluate their effects on the physiological performance of the seeds and to identify the possible metabolic routes involved in the Process of plant defense. The viability, through the germination test and the vigor, were quantified by subjecting the seeds to the tests of accelerated aging, cold test, seedling length and dry matter and field emergence, calculating the rate of emergency, emergency speed and emergency speed coefficient. Plant material, was collected and performed the biochemical analyzes of total proteins, and activity of the enzymes phenylalanine ammonia lyase, chitinase and β-1,3 glucanase. In vitro mycelial growth of the two fungi was affected by the phosphite treatments. Mycelial suppression occurred with potassium phosphite and manganese phosphite. It was found that the best sanitary condition of the seeds was obtained when the mixture of carbendazim + thiram and potassium phosphite was used. The effect of potassium and copper phosphites on corn seed treatment associated with fungicides increased their physiological potential. The treatments did not interfere in the activation of the phenylpropanoic route and in the synthesis of the enzymes chitinase and β-1,3 glucanase when used for the treatment of corn seeds.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The native forest species seeds are the responsible for the maintenance and perpetuation of those in nature, being for natural germination or by programs of seedlings formation for the forest recomposing. The use of fast tests to evaluate the seeds quality and to supply to the producer or nursery the specify information due to the sowing performance is the great importance in the process of seedlings production. The low germination or emergency percentage of plantules can be a consequence of problems as numbness of the seeds, low energy or due to the low physiologic and sanitary quality. The quality of the seeds is a sum of a series of aspects, among them the sanitary quality assumes fundamental importance. The association of pathogenic microorganisms in the seeds could influence the viability, longevity and the pathogenic transmission to the resulting plant. The present work had been evaluated four native forest species: Schizolobium parahyba (Vell.) S. F. Blake, Enterolobium contortisiliquum (Vell.) Morong, Cedrela fissilis (Vell.) and Sesbania virgata Poir, being justified by the economical and ecological importance that they present and their necessary studies, evaluating the seeds and seedlings quality of these species. The present study had been accomplished with the objective of determining the physiologic and sanitary quality of native forest species seeds, coming from Rio Grande do Sul, Santa Catarina and Paraná, through different tests. The experiments had been accomplished in the Phytosanitary Defense Laboratory and in the Forest Nursery. Germination, energy, and sanity tests had been conducted as well as seedlings evaluation starting from these seeds had been done to evaluate the potential of these ones in the good quality seedlings production. The present study had been showed that the pathogen presence as Aspergillus spp. and Penicillium spp. could cause losses in germination due to the seeds rottenness. The presence of these microorganisms is related to the collection and storage conditions in inadequate form. Fungus of Fusarium and Alternaria gender had been found in the seeds of different origins causing interference in the seedlings quality and consequently they had been reduced the establishment of the plants in the field. / As sementes de espécies florestais nativas são as responsáveis pela manutenção e perpetuação destas na natureza, seja pela germinação natural ou por programas de formação de mudas para a recomposição florestal. O uso de testes rápidos para avaliar a qualidade das sementes e fornecer ao produtor ou viveirista informações precisas quanto ao desempenho na semeadura é de grande importância no processo de produção de mudas. A qualidade das sementes é um somatório de uma série de aspectos, dentre os quais a qualidade sanitária assume importância fundamental. A associação de microorganismos patogênicos nas sementes pode influenciar na viabilidade, longevidade e na transmissão para a planta resultante. O presente estudo foi realizado com o objetivo de determinar a qualidade fisiológica e sanitária de sementes das espécies florestais nativas: Schizolobium parahyba (Vell.) S. F. Blake, Enterolobium contortisiliquum (Vell.) Morong, Cedrela fissilis (Vell.) e Sesbania virgata Poir, procedentes do Rio Grande do Sul, Santa Catarina e Paraná, através de diferentes testes. Os experimentos foram realizados no Laboratório de Fitopatologia e no Viveiro Florestal da UFSM. A avaliação da qualidade das sementes foi realizada através dos testes de germinação, vigor e sanidade. A avaliação da qualidade das mudas resultantes foi realizada através de testes em viveiro. O presente estudo mostrou que a presença de patógenos, como Aspergillus spp. e Penicillium spp., podem causar perdas na germinação devido ao apodrecimento de sementes. Fungos do gênero Fusarium e Alternaria, encontrados nas sementes das diferentes procedências, causam interferência na qualidade das mudas e, conseqüentemente, reduzem o estabelecimento das plantas no campo. Através dos testes realizados com as sementes coletadas nos diferentes Estados da Região Sul, foi possível verificar as diferenças dos níveis de vigor e a alta correlação com emergência de plantas no viveiro. Independente do Estado de origem, as sementes das diferentes espécies apresentaram variações na qualidade fisiológica e sanitária.

Bambara groundnut (Vigna subterranea L. Verdc) is a drought tolerant African legume capable of producing reasonable yields where other crops may fail. However, it remains an underutilised crop, owing to limited research, cultivated using landraces, of which scant information is available describing their agronomy and genetic diversity. The aim of this study was to evaluate the response of bambara landraces from different geographical locations to water stress under controlled and field conditions. Seeds were sourced from subsistence farmers of Tugela Ferry and Deepdale in KwaZulu-Natal (South Africa) and Zimbabwe, and characterised into three seed coat colours: light-brown, brown and red. Seed quality was assessed using the standard germination test. Vigour indices of germination velocity index and mean germination time were determined. Seedling establishment was evaluated using seedling trays using a factorial experiment, with four factors: 1. provenance – (Tugela Ferry and Deepdale), 2. seed colour – (red, light-brown and brown), 3. water regimes – (30%, 60% and 100% field capacity), and 4. soil media – (clay, sand and clay + sand). Seedling leaf samples were used to evaluate proline accumulation as an indicator of stress tolerance. A field trial was used to evaluate productivity of bambara landraces under rainfed and irrigated conditions. A pot trial was conducted under controlled environment conditions with three factors: temperature (33/27°C and 21/15°C), water regimes (30% and 100% of crop water requirement) and bambara landrace selections. Results showed no significant differences in germination capacity between bambara landrace selections. Germination time differed significantly (P<0.001) between bambara landrace selections. The Jozini provenance was shown to perform best, followed by Zimbabwe, Tugela Ferry and Deepdale. Brown landrace selections had higher (P<0.001) germination compared with red and light-brown selections, respectively. Seedling establishment showed that emergence was higher (P<0.001) at 100% FC compared with 60% FC and 30% FC. Emergence was higher (P<0.001) in the Sand+Clay mixture compared with Clay and Sand media. Dark-coloured selections had higher (P<0.001) emergence compared with light-coloured selections. Results from the field trial showed that the red landrace selections emerged better (P<0.001) than the light-brown and brown landrace selections, respectively. Plant growth was lower under irrigated compared with rainfed conditions. Stomatal conductance was higher (P<0.001) under irrigated compared with rainfed conditions, whereas chlorophyll content index was higher (P<0.05) under rainfed compared with irrigated conditions. Results of the pot trial showed that emergence was significantly (P<0.001) affected by temperature. It was higher at 33/27°C compared with 21/15°C (P<0.001). Dark-coloured landraces had higher emergence compared with the light-brown landraces. Stomatal conductance was lower at 30% ET relative to 100% ETc. There were no significant differences between water regimes with respect to biomass, pod number per plant, pod mass per plant, seed number per pod, seed mass per plant and harvest index. It is concluded that seed colour is an important variable in the identity of bambara landraces. Provenance plays a significant role in seed performance and there is a significant interaction between provenance and seed coat colour. This study could be expanded to obtain more data for crop improvement through inclusion of many sites and seasons for better agronomic advice to farmers. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.