Made available in DSpace on 2014-06-11T19:28:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-18Bitstream added on 2014-06-13T18:35:04Z : No. of bitstreams: 1 000754448.pdf: 1348251 bytes, checksum: 8fde2d8307ee7de4fcd2c5fe29feb1e8 (MD5) / A arquitetura das plantas pode ser modificada pelas práticas de condução da cultura influenciando assim aspectos fitossanitários e a produtividade. Diante disso, este trabalho teve como objetivo verificar a influência de diferentes arranjos de plantio na população de pragas e nas características morfofisiológicas na cultura da soja. O experimento foi composto por oito tratamentos, sendo quatro sistemas de plantio com diferentes espaçamentos entre linhas e duas cultivares de soja, uma de hábito de crescimento determinado e outra indeterminado e quatro repetições com parcelas de 12 x 07 m. Foram avaliados utilizando a população de insetos-praga, os danos de percevejos, os parâmetros morfofisiológicos, e ao final do ciclo as variáveis agronômicas e produtividade. Em relação à população de insetos-praga os sistemas de plantio convencional e fileira dupla foram os que tiveram maior ocorrência de lagartas desfolhadoras. Quanto à população de percevejos e inimigos naturais não houve diferença entre os tratamentos. No teste de tetrazólio houve maior quantidade de danos nos grãos no sistema de fileira dupla. A condição fisiológica das plantas de soja se manteve melhor nos sistemas de plantio convencional e fileira dupla, porém para os parâmetros de razão da área foliar (RAF) e área foliar específica (AFE) não houve diferença. O sistema de plantio reduzido apresentou maior quantidade de ramificações e consequentemente maior quantidade de vagens e grãos, entretanto este incremento não refletiu na produção, pois os tratamentos não diferiram entre si quanto à produtividade. / The architecture of the plants can be modified by the driving practices of culture influencing plant health and productivity. Thus, this study aimed to investigate the influence of different planting arrangements in the pest population and the morphophysiological traits in soybean. The experiment consisted of eight treatments, four tillage systems with different row spacings and two soybean cultivars, one of determinate growth habit and other indeterminate and four replications with plots of 12 x 07 m. Were evaluated using the population of insect pests, stink bug damage, the morphophysiological parameters , and at the end of the cycle variables agronomic and productivity. In relation to the population of insect pests conventional tillage systems and double row were those who had a higher incidence of defoliating caterpillars. As the population of bed bugs and natural enemies there was no difference between treatments. In tetrazolium test a higher amount of damage to grain in double row system. The physiological condition of the soybean plants kept in the best of conventional and double row planting systems, but for the parameters of leaf area ratio (RAF) and specific leaf area (AFE) there was no difference. The system of reduced tillage had greater amount of branching and hence larger amount of beans and grains, however this increase was not reflected in production because the treatments did not differ in terms of productivity.

Made available in DSpace on 2014-06-11T19:30:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-17Bitstream added on 2014-06-13T20:20:55Z : No. of bitstreams: 1 castro_gsa_dr_botfca.pdf: 1328477 bytes, checksum: c1e2eb0cff4b260bbc7fb57c43d6fa89 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo desta tese foi avaliar a influência da aplicação superficial de corretivos em diferentes sistemas de produção sobre Sistema Plantio Direto, bem como o efeito de ambas as variáveis nos atributos físicos, na movimentação de bases, na correção da acidez do solo, nas frações da matéria orgânica do solo, além da nutrição e produtividade das culturas produtoras de grãos em região de inverno seco. O presente trabalho é a continuação de um experimento instalado no ano agrícola 2006/2007, na Fazenda Experimental Lageado, pertencente à Faculdade de Ciências Agronômicas – UNESP, localizada no município de Botucatu (SP), e foi conduzido nos anos agrícolas 2008/2009, 2009/2010 e 2010/2011. O delineamento experimental foi blocos casualizados, no esquema de parcelas subdivididas, com 8 repetições. As parcelas foram constituídas por quatro sistemas de produção (“Safra - Forrageira”; “Safra – safrinha”; “Safra – Pousio” e; “Safra – Adubo Verde”) e as subparcelas por duas fontes de corretivos de acidez e um controle (calcário; silicato de cálcio e magnésio; sem aplicação de corretivo). Foram realizadas as seguintes avaliações: produção de massa de matéria seca e teores de macronutrientes e silício em todas as culturas; componentes de produção das culturas graníferas; atributos químicos do solo aos 36 e 48 meses após a aplicação dos corretivos (outubro de 2006); atributos físicos do solo e fracionamento da matéria orgânica do solo após a colheita da terceira safra de outono/inverno (60 meses após a aplicação dos corretivos); e custo de produção das unidades experimentais. Com o presente estudo, pôde-se concluir que: A aplicação de corretivos influencia positivamente o teor de matéria orgânica... / This thesis had the objective of evaluating the influence of superficial application of correction sources in different cropping rotations under no tillage system on soil physical properties, base mobility, acidity correction, organic matter fractioning as well as crop nutrition and yield in dry winter region. The present study was conducted in 2008/2009, 2009/2010 and 2010/2011 and it was a sequence of an experiment that had been conducted since 2006/2007 in College of Agricultural Sciences – FCA/UNESP, in Botucatu-SP, Brazil. The experimental design was the complete randomized block with subdivided plots and eight replications. Main plots consisted of four cropping rotations (“Season-Forage”; “Season-Offseason”; “Season-Fallow” and “Season-Green manure”) and subplots by two sources for soil acidity correction (dolomitic lime, calcium/magnesium silicate) plus a control, with no correction. The following evaluations were conducted: dry matter production, macronutrient levels and silicon levels in all crops, yield components of grain crops, soil chemical attributes at 36 and 48 months after correction (October 2006), soil physical attributes and organic matter fractioning in fall/winter of 2011 (60 months after correction), and production costs. It was concluded that the application of correction sources positively influences organic matter levels, increasing stocks of total organic carbon, particulate organic carbon and mineralassociated carbon. Best results are observed under “Season-Forage” rotation, opposed to “Season-Fallow” system. Chemical benefits of correction sources on soil fertility are still observed 48 months after the application. Soil correction increases phosphorus levels in soil, although silicate is more efficient than lime. Crop rotations improve aggregate stability and reduce penetration... (Complete abstract click electronic access below)

From the Introduction. The fertilisation of pineapples in the Eastern Cape Province is still a relatively new practice which started approximately twelve years ago. Even after this time many growers still insist that pineapples can be grown without fertilisation on virgin soils. As the available virgin soil decreased, however, so the interest in fertiliser application increased. Very little basic research on the fertiliser requirements of pineapples in the Eastern Cape was done to serve as a guide to growers. The available advisory literature by le Roux (1951), Malan (1954) and Lewcock (1956) were based on overseas experience. When pineapple research was started on a large scale, in 1955, it was realised that emphasis should be placed on the nutritional requirements on virgin as well as replanted soils. From initial experiments it was clear that the main response in plant growth and yield was obtained from nitrogenous fertilisers.

Please read the abstract in the 00front part of this document / Dissertation (MSc (Agricultural Economics))--University of Pretoria, 2007. / Agricultural Economics, Extension and Rural Development / unrestricted

No description available.

Thesis (M.Sc. (Pasture Science)) -- University of Limpopo, 2022 / In South Africa, livestock production is a rapidly growing business in the agricultural sector contributing up to 46.9% of the gross domestic value. The shortage of adequate, good quality forage during the winter months is one of the biggest problems confronting livestock farmers in the Limpopo Province. This study was initiated in 2019 to evaluate the production potential and nutritive value of different summer annual forage legumes, namely sunnhemp (Crotalaria juncea), forage cowpea (Vigna unguiculata), lablab bean (Lablab purpureus), and pigeon pea (Cajanus cajans), and their impact on succeeding winter stooling ryegrass (Secale cereale), at the University of Limpopo experimental farm Syferkuil and a Cooperative farmers’ field at Ofcolaco. The study was evaluated in a randomized complete block design with four replications. Dry matter yield, crude protein, crude protein yield, leaf chlorophyll content, Normalized Difference Vegetative Index (NDVI), and leaf gaseous exchange parameters of forage crops were statistically analysed with Statistical Analysis System (SAS), Enterprise Version 9.4, using the least significant difference (LSD) method for mean comparison. Pigeon pea biomass accumulation was 57% lower than the average of the three other legumes at Syferkuil. Sunnhemp produced superior biomass (P<0.05) compared to the other three species, reaching a peak yield of 3142.4 kg.ha-1 and 8970.8 kg ha-1 at Syferkuil and Ofcolaco, respectively. Cowpea and lablab produced similar biomass at Syferkuil. The crude protein content of the forage species ranged from 22.91% to 26.82% at Syferkuil and 17.03% to 23.84% at Ofcolaco. Leaf chlorophyll content differed (P<0.001) among the forage legume species at both locations with cowpea producing the highest chlorophyll content at Syferkuil, whereas at Ofcolaco, pigeon pea constantly produced the highest chlorophyll compared to other species. Pigeon pea was the only species rated moderately healthy with Normalised Difference Vegetative Index (NDVI) readings at Syferkuil, unlike at Ofcolaco where all forage legumes were rated as very healthy. At Syferkuil, no root nodules were observed among all the forage legumes at all sampling dates but at Ofcolaco, nodules were produced at 44 DAE with cowpea producing the highest, 92.32% higher than the average of sunnhemp, lablab, and pigeon-pea. At this location pigeon pea did not nodulate. The transpiration rate at Syferkuil was significant (P<0.01) among the species starting with a low transpiration rate from 24 days after planting and reaching their peak at 66DAE. Overall, pigeon pea had the highest (P<0.05) mean transpiration rate compared to the other species. At Ofcolaco the forage legume treatment did not have any significant (P>0.05) influence on transpiration rate, stomatal conductance and sub-stomatal conductance. The transpiration rate of the species ranged from 0.1 mol m-2 s -1 to 5.15 mol m-2 s -1 across all sampling dates whereas stomatal conductance ranged from 0.06 to 5.59 mol m-2 s -1 at Syferkuil and 0.1 to 5.15 mol m-2 s -1 at Ofcolaco, across all sampling dates and species. At Syferkuil, the mean stomatal conductance values ranged from 129.75 mol m-2 s -1 to 374 mol m-2 s -1 across the sampling dates and species, whereas, at Ofcolaco, the means ranged from 185 mol m-2s -1 to 390.25 mol m-2s -1 . The succeeding stooling rye produced a similar biomass yield under every preceding forage legume. This can be concluded that all the four forage legumes did not have any effect on the biomass production of stooling rye. However, there appeared to be a tendency of higher biomass production in the grass species grown after pigeon pea and lablab compared to those following sunnhemp and cowpea. Further experiments are required to establish the full benefits of the forage legumes on succeeding forage grass crop. Based on the results from this study, it was concluded that sunnhemp can be considered as the first choice forage legume at both Syferkuil and Ofcolaco due to its consistently high biomass production, comparable nutrient profile, high crude protein content and high protein yield compared with the other legumes. Though sunnhemp was superior, the other forage summer legumes species studied also managed to produce enough biomass for grazing and had similar nutritive value which was above minimum recommendations. They can therefore be cultivated in the province to meet the constraint of the feed gap in the province. Additional studies at different locations, however, will help to understand the productivity of the species and also to establish the full benefits of the forage legumes on succeeding forage grass crops / National Research Foundation (NRF) and Department of Science and Innovation

Eastern Virginia grain producers face production and marketing decisions under conditions of considerable yield and price variability. Traditionally MOTAD and other risk programming models have relied on the variability of historical returns series as a proxy for the risk an individual producer experiences. The mean forecast deviation method provides an alternative to the standard method of calculating deviations for MOT AD models. This method was applied to an eastern Virginia cash grain farm to provide a farm plan based on expected prices during the first week of February. The acreages of com, soybeans, and small grains were specified based on soil type, government program participation, sales at harvest, storage, pre-harvest hedging, and post-harvest hedging. The expected farm plans for the 1987 crop year resulted in participation in the government commodity programs at all levels of risk aversion and for each crop and soil type. Elimination of government commodity programs from the model resulted in two major findings: wheat and barley doubled cropped with soybeans preformed well on both soil types and at all levels of risk aversion, and given 1987 expected prices, idling lower quality land was a profitable decision at all levels of risk aversion. / Master of Science

Surtos de pragas em lavouras são imprevisíveis em relação ao local e ao momento. Contudo, um programa manejo integrado de pragas eficiente depende do conhecimento da distribuição dos insetos o mais cedo possível, antes que a população esteja bem estabelecida e atinja o Nível de Dano Econômico. É possível, no entanto, identificar no campo fatores que podem tornar as plantas mais atrativas a esses insetos, como o estresse hídrico. Uma possível maneira de tentar prever os surtos de pragas é pelo diagnóstico da suscetibilidade das plantas às pragas. Nesse sentido, objetivou-se com esse trabalho descrever os padrões de reflectância de plantas de soja estressadas, tanto pela restrição hídrica quanto pela infestação por Bemisia tabaci biótipo B. Para tanto, plantas de soja foram cultivadas em casa de vegetação sob diferentes regimes hídricos (30, 50, 70 e 100% de reposição do volume de água perdido diariamene) e oferecidas a adultos de B. tabaci biótipo B em ensaios com e sem escolha. Todas plantas utilizadas nos bioensaios foram previamente avaliadas quanto à sua reflectância utilizado o sensor hiperespectral FieldSpec&reg; 3, para posterior classificação nos grupos relativos ao regime hídrico imposto. Após os ensaios de suscetibilidade, foram realizados ensaios para determinar a possibilidade de uso do sensor hiperespectral para classificação de plantas estressadas, tanto pelo estresse hídrico, quanto pela infestação por B. tabaci biótipo B, em um esquema fatorial. Os regimes hídricos utilizados foram 70 e 100% de reposição e, ensaios com infestação controlada e não-controlada foram realizados. Nos ensaios de suscetibilidade, foi possível observar que, quando têm escolha, adultos de B. tabaci biótipo B depositam mais ovos em plantas cultivadas com 70 e 50% de reposição do volume de água perdida. Já quando os adultos não têm escolha, diferenças estatísticas entre a quantidade de ovos depositados nos regimes testados não foram encontradas. Quanto à classificação das plantas em grupos, pode-se afirmar que o sensor hiperespectral FieldSpec&reg; 3 fornece informação suficiente para tanto. No ensaio de infestação controlada, quatro grupos foram gerados, 70% de reposição do volume de água com infestação, 70% de reposição sem infestação, 100% de reposição com infestação e 100% de reposição sem infestação. A análise discriminante dos dados de reflectância demonstrou que, ao final do ensaio, os quatro grupos são significativamente diferentes. Ainda, com uma validação cruzada, foi possível classificar os respectivos grupos com 73,81% de precisão. No ensaio com infestação não controlada, as plantas infestadas foram classificadas em 3 grupos de acordo com o nível de infestação, baixa, média e alta. Da mesma maneira, a análise discriminante dos dados de reflectância demonstrou que há diferença entre os grupos e, a validação cruzada indicou que é possível classificar o nível de infestação com 91,98% de precisão. Portanto, conclui-se que o sensoriamento remoto hiperespectral pode somar ao manejo integrado de pragas, tanto na avaliação da suscetibilidade das plantas às pragas, quanto na identificação de plantas infestadas e sadias. / Pest outbreaks in commercial fields are unpredictable in relation to location and timing. However, an efficient Integrated Pest Management depends on the knowledge of the distribution of the insects as early as possible, before the population is established and reaches the threshold of Economic Injury. It is possible, however, to identify factors in the field that may make plants more attractive to insects, such as water stress. One possible way to try to predict pest outbreaks is to diagnose the susceptibility of plants to insects. Thus, the objective of this study is to describe the reflectance patterns of soybean plants stressed by either water stress and Bemisia tabaci biotype B infestation. Soybean plants were grown in greenhouse under different irrigation regimes (30, 50, 70 and 100% daily water recharge), and offered to B. tabaci Biotype B adults in both choice and non-choice bioassays. All the plants used in the bioassays were previously evaluated for their reflectance, using the FieldSpec&reg; 3 hyperspectral sensor, to classify them later in the irrigation groups. After the susceptibility bioassays, new studies were carried out to evaluate the feasibility of using the hyperspectral sensor to classify plants under infestation and water stress, in a factorial scheme. Irrigation regimes were 70 and 100% daily water refill, and tests were performed with controlled and uncontrolled infestation. In the susceptibility tests, it was possible to observe that, when given the options, B. tabaci Biotype B adults lay more eggs in plants grown with 70 and 50% daily water refill. When adults have no options, no significant difference was observed between the amount of eggs deposited in all irrigation regimes. Regarding the classification of plants in groups, it is possible to state that the FieldSpec&reg; 3 hyperspectral sensor provides sufficient information for this. In the controlled infestation trial, four distinct groups were generated, 70% water refill + infestation, 100% water refill + infestation, 70% water refill without infestation and 100% water refill without infestation. Discriminant analysis showed that, after the assay, the groups were statistically different. In addition, using a cross-validation, it was possible to classify the groups with 73.81% accuracy. In the test with uncontrolled infestation, three groups were generated, according to the level of infestation: low, medium and high. Likewise, the Discriminant analysis showed that there is a significant difference between the groups, and cross validation indicated that it is possible to classify the level of infestation with 91.98% accuracy. Therefore, it is possible to conclude that hyperspectral remote sensing may be an additive tool for Integrated Pest Management, both to evaluate the susceptibility of plants to pests and to identify healthy and infested plants.

The NRT2 (high affinity nitrate transporter 2) family is a part of the iHATS (inducible high affinity system) that studies have shown is responsible for the influx of nitrate into the plant cell after provision of nitrate. The ZmNRT2.1 from Zea mays was constitutively expressed in Nicotiana tabacum. To assess how over-expression of this foreign NRT2.1 affects nitrate influx by plants, nitrate content in leaf and root tissue, gene expression, and vegetal growth were analyzed in media with deficient or high nitrate concentrations (0.1, 1, or 10 mM). Compared to wild type plants: the transgenic lines had a significantly larger fresh weight in all nitrate conditions; primary root length was significantly longer in the 0.1 and 1 mM nitrate conditions; both the fresh weight and the primary root length were significantly higher when 50 mM NaCl was applied as a stress factor to medias containing 0.1 and 10 mM nitrate. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Understanding climatic impacts is important if we are to comprehend the relationship between climate and society. Weather phenomena can have environmental, economical, and social impacts. Drought is the natural hazard that affects people the most. It is also the most complex and least understood. There is no one universally accepted definition for drought which makes its examination difficult. Droughts’ duration is also difficult to determine because it has no clearly defined onset and end. Also, drought varies both geographically and temporally making uniform drought monitoring difficult. Since drought is difficult to monitor and access, drought impacts are often poorly documented. The purpose of this research was to quantify (in dollars) the impacts of drought on Kentucky’s agriculture. Drought has been recorded historically in Kentucky since the late 1800s. According to the Kentucky Climate Center, the most significant drought years occurred in 1930-31, 1940-42, and 1952-55. Analyses of these years are included as well as the most recent significant drought years in 1987-88, 1999- 2000 and 2007. Four of Kentucky’s important commodities, including corn, soybeans, hay, and beef cattle, were examined during the significant drought years. The total state revenue for these commodities was analyzed during severe drought years vs. non-severe drought years. The result of this research identified how much of a deficit severe drought causes on Kentucky revenue for each of these commodities. This research is important to the general public as well as planners and policy makers. Proper documentation of drought impacts will help identify drought vulnerabilities and result in better risk management and mitigation. Key Words: Drought, Agriculture, Impact Assessment