• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 71
  • 21
  • 10
  • 10
  • 10
  • 10
  • 10
  • 10
  • 7
  • 4
  • 2
  • 1
  • 1
  • Tagged with
  • 150
  • 150
  • 28
  • 23
  • 21
  • 18
  • 17
  • 16
  • 16
  • 15
  • 15
  • 15
  • 14
  • 13
  • 12
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Distribuição de plantas de milho em sistema pneumático com diferentes regulagens de pressão de vácuo e peneiras de sementes / Distribution of corn plants in a pneumatic system with different vacuum pressure settings and seed size

Madalóz, José Carlos Cazarotto 26 March 2018 (has links)
O objetivo deste trabalho foi avaliar a influência do tamanho da peneira de sementes de milho sob diferentes regulagens da pressão de vácuo em sistema pneumático de distribuição, sobre a uniformidade longitudinal de plantas, produtividade final e individual por planta. O ensaio foi conduzido no município de Verê/PR. Foi utilizado o sistema pneumático de distribuição vSet® (Precision Planting®) e 4 peneiras de sementes de milho (C1; C4; R1; e R4) do híbrido 30F53VYH, submetidos a 4 diferentes regulagens da pressão de vácuo (7; 12; 17 e 22 pol H2O-1). O delineamento utilizado foi de blocos ao acaso, com parcelas subdivididas e 4 repetições. Na parcela principal constaram as pressões e nas subparcelas as peneiras, sendo cada uma desta composta por duas linhas de 20 m de comprimento. Inicialmente, foram caracterizadas as sementes, avaliando-se o percentual de germinação, peso de mil sementes, comprimento, largura, espessura e esfericidade. Após a emergência das plantas, foram avaliadas a uniformidade de distribuição, através dos parâmetros de regularidade (espaçamentos normais – EN; espaçamentos falhos – EF; espaçamentos duplos – EP), desvio padrão (DP), coeficiente de variação (CV) e uniformidade média de distribuição, a profundidade de semeadura e a população inicial. Em pré-colheita, avaliou-se a população final de plantas, percentual de plantas dominadas, rendimento de grãos por planta e total. Os dados foram submetidos a análise de variância e havendo diferenças significativas (p≤0,05), as médias das peneiras foram comparadas pelo teste de Tukey (p≤0,05), enquanto que para o fator pressão de trabalho foi adotada a análise de regressão polinomial, sendo os modelos selecionados pelo critério do maior R2 e a significância (p≤0,05) dos parâmetros da equação. A redução da pressão de vácuo resultou no aumento do DP, sendo que a peneira R1 apresentou os maiores valores e a peneira C4 os menores valores. Independente da pressão e peneira testada os valores de CV não foram significativos. A peneira C1 apresentou os menores índices de ED e, a C4 os maiores. Menores pressões de vácuo resultaram em maiores índices de EF, com a peneira C4 apresentando os menores valores, tendo esta também os maiores índices de EN. As peneiras C1 e R1 responderam negativamente, quanto a uniformidade média de distribuição de plantas, com a redução da pressão de vácuo. A peneira R1 apresentou a menor população inicial de plantas, mas a peneira C1 apresentou redução da população final de plantas e rendimento de grãos com a redução da pressão. Plantas dominada e de ED tendem a produzir menor número de grãos por espiga e, consequentemente, menor rendimento individual de grãos. As espigas de plantas vizinhas a EF não tiveram capacidade de compensar em produtividade à falta da planta. / The objective of this work was to evaluate the influence of the seed size of the corn under different vacuum pressure regulations in a pneumatic distribution system, on a plant distribution, final and individual productivity per plant. The trial was conducted in the city of Verê / PR. The pneumatic vSet® distribution system (Precision Planting®) was used. Four size of 30F53VYH hybrid corn seeds (C1, C4, R1, and R4) were submitted to four different vacuum pressure settings (7; 12; 17; 22 in H2O-1). The design was used for randomized blocks, with subdivided plots, and 4 replicates. In the main plot they consisted as pressures and in the subplots like size seeds, being each of the main lines of 20 m of length. Initially, they were characterized as seeds, evaluating the percentage of germination, weight of one thousand seeds, length, width, thickness and sphericity. After the emergence of the plants, the longitudinal distribution uniformity was evaluated through the parameters of longitudinal distribution (miss, multi and normal), standard deviation (SD), coefficient of variation (CV) and mean distribution uniformity, seeding depth and initial population. In pre-harvest, we evaluated the final population of plants, percentage of dominated plants, yield per plant and total. The data were submitted to an analysis of variance and there were significant differences (p≤0.05), as means of the sizes were compared by the Tukey test (p≤0.05), while for the working pressure factor, polynomial regression analysis, the models being selected by criterion the highest R2 and the significance (p≤0.05) of the parameters of the equation. The reduction of the vacuum pressure resulted in the increase of the SD, being that the size R1 presents the highest values of SD and the size C4 the lowest values. Regardless of the pressure and the size tested in the CV values were not significant. The size C1 has the lowers multi rates and, a larger C4. Lower vacuum pressures result in higher miss indexes, with a size C4 having the lowest values, and also the highest normal rates. As sizes C1 and R1 responding negatively, as for the average uniformity of plant distribution, with a reduction of vacuum pressure. The size R1 has a smaller population of plants, but the size C1 showed reduction of the final population of plants and yield of grains with a reduction of the pressure. Dominated and multi plants tend to produce a smaller number of kernels per ear, consequently lower individual yield of grains. Like spikes of neighboring plants, an miss plants does not have the capacity to compensate in productivity to the lack of the plant.
122

Impacto da inclusão de leguminosa em pastagem hibernal sobre o milho cultivado em sucessão em sistema de integração lavoura-pecuária / The impact of including leguminous crops in a winter grazing on the corn grown in succession in a crop-livestock integration system

Oliveira, Jonathan Kaoan de 20 May 2016 (has links)
Os sistemas integrados de produção agropecuários (SIPA), tem como finalidade a diversificação, rotação, consorciação e/ou sucessão de atividades agrícolas, possibilitando que cada atividade contribua positivamente e beneficie a atividade em sucessão ou simultânea. O objetivo deste trabalho foi avaliar a produtividade do milho submetido a níveis de adubação nitrogenada em sucessão ao consórcio formado por ervilhaca, aveia-preta e azevém e à resposta a inclusão da ervilhaca na cultura do milho, assim como o efeito do pastejo em um sistema de integração lavoura pecuária. O trabalho foi desenvolvido na Universidade Tecnológica Federal do Paraná (UTFPR), onde na parcela principal foram alocadas a combinação de espécies forrageiras: aveia + azevém e aveia + azevém + ervilhaca. Utilizou-se como adubação de base 32 kg ha-1 de N, 80 kg ha-1 de P2O5 e 60 kg ha-1 de K2O. Nas subparcelas as cinco doses de nitrogênio, na forma de ureia, aplicado em cobertura no milho (0, 75, 150, 225 e 300 kg ha-1) nas áreas com pastejo, e (0, 150 kg ha1 nas subparcelas sem pastejo.Avaliou-se a produção de silagem (kg ha-1 de MS),rendimento de grãos de milho (kg ha-1), população de plantas (plantas ha-1) e os componentes de rendimento, fileiras por espiga, grãos por fileira, grãos por espiga, massa de mil grãos (g), nitrogênio absorvido (kg ha-1) e no tecido (g kg-1)de plantas de milho.Nos componentes rendimento de grãos de milho e produção de silagem foram superiores nas áreas com cultivo de ervilhaca e apresentou uma resposta até a dose 250 kg ha-1 de N, enquanto que nas áreas sem ervilhaca no cultivo anterior, a resposta foi linear até a dose máxima utilizada. A utilização da ervilhaca consorciada com aveia e azevém em áreas é uma alternativa para diminuir o uso da adubação nitrogenada na cultura de milho cultivada em sucessão no sistema de integração lavoura pecuária, tanto para produção de silagem quanto para produção de grãos, além de propiciar um aumento nos teores de nitrogênio no tecido de plantas de milho. / The integrated agricultural production systems (SIPA) has the purpose of diversification, rotation, intercropping and / or succession of agricultural activities, allowing each activity to contribute positively and benefit the activity in succession or a simultaneous one. The objective of this paper was to evaluate the productivity of corn submitted to nitrogen fertilization levels in succession to the consortium of vetch, oat and ryegrass and addressing the inclusion of vetch in maize, as well as the effect of grazing on a livestock farming integration system. The study was conducted at the Federal Technological University of Paraná (UTFPR), where in the main plot were allocated the combination of forage species: oat + ryegrass and oats + ryegrass + vetch. A base fertilizer of 32 kg ha-1 N, 80 kg ha-1 P2O5 and 60 kg ha-1 K2O was used. In the subplots, five levels of nitrogen, in the form of urea, were applied to cover the corn (0, 75, 150, 225 and 300 kg ha-1) in areas with grazing, and (0, 150 kg ha1) in subplots ungrazed . We evaluated the production of silage (kg ha-1 DM) yield of corn grain (kg ha-1), plant population (plants ha-1) and yield components, rows per ear, kernels per row, grains per ear, thousand grain weight (g) absorbed nitrogen (kg ha-1) and tissue (g kg-1) of corn plants. In the components, yield of corn grain and silage production were higher in areas with vetch cultivation and responded until the dose of 250 kg ha-1 N, while in areas without vetch in the previous crop, the response was linear up to the maximum dose used. The use of vetch intercropped with oats and ryegrass in areas is an alternative way to reduce the use of nitrogen fertilizer in corn grown in succession in livestock farming integration system, both for silage and for grain production, as well as providing an increase in nitrogen concentration in the tissue of maize plants.
123

Fenologia e produtividade de cultivares de videiras para suco em sistema agroecológico / Phenology and productivity of grapevine cultivars for juice in an agroecological system

Mariani, Josiane Aparecida 25 August 2017 (has links)
CAPES; UTFPR / A produção brasileira de uvas para elaboração de sucos vem se tornando uma importante alternativa de renda aos agricultores familiares, motivada pelo aumento no incentivo do seu consumo. Existem diversas cultivares adaptadas à produção de sucos, no entanto, algumas das cultivar recém-lançadas no mercado brasileiro ainda não foram suficientemente testadas em regiões de clima subtropical, a exemplo do Sudoeste do Paraná, justificando esse trabalho de pesquisa. Diante do exposto, objetivou-se com o presente trabalho avaliar o requerimento térmico, a qualidade e a produtividade das uvas de 15 cultivares: Bordô, BRS Carmen, BRS Lorena, BRS Magna, BRS Rúbea, BRS Violeta, Concord, Concord Clone 30, Isabel, Isabel Precoce, Moscato Embrapa, Moscato Bailey, Niagara Branca, Niagara Rosada e Seibel 5455,produzidas no sistema agroecológico em duas safras agrícolas, 2015/2016 e 2016/2017, em Dois Vizinhos, Paraná. As videiras foram implantadas em 2012, no sistema de condução de espaldeira. Para o estímulo da brotação das gemas foi utilizado calda sulfertilizante (sulfocálcica) a 5,0% + óleo mineral a 2,0%. Avaliou-se semanalmente a fenologia das plantas utilizando-se cinco estádios fenológico e obteve-se os requerimentos térmicos das videiras para distintos períodos do desenvolvimento das plantas, bem como o ciclo das mesmas. A exigência térmica foi definida pelo cálculo de acumulo de graus-dia (GD) desde o estádio de gema inchada até a colheita. Também foram realizadas avaliações de variáveis agronômicas a campo, como a determinação de componentes de rendimento, sendo número de cachos por planta, biomassa fresca de cachos, estimativa de produtividade (kg.planta-1 e t.ha-1). Também foram avaliados atributos químicos de qualidade dos sucos (mostos) obtidos, como: teores de sólidos solúveis (SS) em °Brix, pH, acidez titulável (AT) em percentagem e a relação entre os teores de SS/AT. As cultivares BRS Violeta, Isabel Precoce e Seibel 5455 são as mais produtivas. A cultivar Seibel 5455 possui maior requerimento término e ciclo mais tardio. A BRS Magna e BRS Violeta possuem menores requerimentos térmicos e ciclos mais precoces. As cultivares de videiras BRS Rúbea, BRS Violeta, Isabel, Moscato Embrapa, Moscato Bailey, Niagara Branca e Niagara Rosada apresentam teores de sólidos solúveis, pH e acidez desejáveis para a elaboração de sucos integrais de qualidade. O melhor ano-safra de cultivo foi 2016/2017 proporcionou as condições climáticas mais favoráveis à superação de dormência das gemas, brotação, floração e produção das videiras. / The Brazilian production of grapes for juice production has become an important income alternative for family farmers, motivated by the increase in the incentive of their consumption. There are several cultivars adapted to the production of juices, however, some of the cultivars recently launched in the Brazilian market have not yet been sufficiently tested in regions of subtropical climate, as in the southwestern region of Paraná, justifying this research work. In the present work, the objective of this study was to evaluate the thermal requirements, quality and productivity of the 15 grapes cultivar: Bordô, BRS Carmen, BRS Lorena, BRS Magna, BRS Rúbea, BRS Violeta, Concord, Concord Clone 30, Isabel, Isabel Precoce, Moscato Embrapa, Moscato Bailey, Niagara Branca, Niagara Rosada and Seibel 5455, produced in the agroecological system in two agricultural crops, 2015/2016 and 2016/2017, in Two Neighbors, Paraná state, Brazil. The vines were implanted in 2012, in the driving system of espaldeira. To stimulate bud buds, sulfer fertilizer solution (sulphocalcium) at 5,0% + mineral oil at 2,0% was used. The phenology of the plants was evaluated weekly using five phenological stages and the thermal requirements of the vines were obtained for different periods of the development of the plants, as well as the cycle of the same ones. The thermal requirement was defined by the calculation of day-degree accumulation (GD) since swollen buds stage to the harvest. Also evaluations of field agronomic variables were performed, such as determination of yield components, number of bunches per tree, fresh bunker biomass, yield estimate (kg.planta-1 e t.ha-1). Also, the quality of the juices (musts) obtained, such as: soluble solids (SS) in ° Brix, pH, titratable acidity (AT) in percentage and the ratio of SS/AT contents were evaluated. The cultivars BRS Violeta, Isabel Precoce and Seibel 5455 are the most productive. The cultivar Seibel 5455 has a higher end and later cycle requirement. BRS Magna and BRS Violeta have lower thermal requirements and earlier cycles. The cultivars of BRS Rúbea, BRS Violeta, Isabel, Moscato Embrapa, Moscato Bailey, Niagara Branca and Niagara Rosada grapevines have soluble solids, pH and acidity levels desirable for the production of quality whole juices. The best crop year was 2016/2017 provided the most favorable climatic conditions to overcome bud dormancy, budding, flowering and vines production.
124

Impacto da inclusão de leguminosa em pastagem hibernal sobre o milho cultivado em sucessão em sistema de integração lavoura-pecuária / The impact of including leguminous crops in a winter grazing on the corn grown in succession in a crop-livestock integration system

Oliveira, Jonathan Kaoan de 20 May 2016 (has links)
Os sistemas integrados de produção agropecuários (SIPA), tem como finalidade a diversificação, rotação, consorciação e/ou sucessão de atividades agrícolas, possibilitando que cada atividade contribua positivamente e beneficie a atividade em sucessão ou simultânea. O objetivo deste trabalho foi avaliar a produtividade do milho submetido a níveis de adubação nitrogenada em sucessão ao consórcio formado por ervilhaca, aveia-preta e azevém e à resposta a inclusão da ervilhaca na cultura do milho, assim como o efeito do pastejo em um sistema de integração lavoura pecuária. O trabalho foi desenvolvido na Universidade Tecnológica Federal do Paraná (UTFPR), onde na parcela principal foram alocadas a combinação de espécies forrageiras: aveia + azevém e aveia + azevém + ervilhaca. Utilizou-se como adubação de base 32 kg ha-1 de N, 80 kg ha-1 de P2O5 e 60 kg ha-1 de K2O. Nas subparcelas as cinco doses de nitrogênio, na forma de ureia, aplicado em cobertura no milho (0, 75, 150, 225 e 300 kg ha-1) nas áreas com pastejo, e (0, 150 kg ha1 nas subparcelas sem pastejo.Avaliou-se a produção de silagem (kg ha-1 de MS),rendimento de grãos de milho (kg ha-1), população de plantas (plantas ha-1) e os componentes de rendimento, fileiras por espiga, grãos por fileira, grãos por espiga, massa de mil grãos (g), nitrogênio absorvido (kg ha-1) e no tecido (g kg-1)de plantas de milho.Nos componentes rendimento de grãos de milho e produção de silagem foram superiores nas áreas com cultivo de ervilhaca e apresentou uma resposta até a dose 250 kg ha-1 de N, enquanto que nas áreas sem ervilhaca no cultivo anterior, a resposta foi linear até a dose máxima utilizada. A utilização da ervilhaca consorciada com aveia e azevém em áreas é uma alternativa para diminuir o uso da adubação nitrogenada na cultura de milho cultivada em sucessão no sistema de integração lavoura pecuária, tanto para produção de silagem quanto para produção de grãos, além de propiciar um aumento nos teores de nitrogênio no tecido de plantas de milho. / The integrated agricultural production systems (SIPA) has the purpose of diversification, rotation, intercropping and / or succession of agricultural activities, allowing each activity to contribute positively and benefit the activity in succession or a simultaneous one. The objective of this paper was to evaluate the productivity of corn submitted to nitrogen fertilization levels in succession to the consortium of vetch, oat and ryegrass and addressing the inclusion of vetch in maize, as well as the effect of grazing on a livestock farming integration system. The study was conducted at the Federal Technological University of Paraná (UTFPR), where in the main plot were allocated the combination of forage species: oat + ryegrass and oats + ryegrass + vetch. A base fertilizer of 32 kg ha-1 N, 80 kg ha-1 P2O5 and 60 kg ha-1 K2O was used. In the subplots, five levels of nitrogen, in the form of urea, were applied to cover the corn (0, 75, 150, 225 and 300 kg ha-1) in areas with grazing, and (0, 150 kg ha1) in subplots ungrazed . We evaluated the production of silage (kg ha-1 DM) yield of corn grain (kg ha-1), plant population (plants ha-1) and yield components, rows per ear, kernels per row, grains per ear, thousand grain weight (g) absorbed nitrogen (kg ha-1) and tissue (g kg-1) of corn plants. In the components, yield of corn grain and silage production were higher in areas with vetch cultivation and responded until the dose of 250 kg ha-1 N, while in areas without vetch in the previous crop, the response was linear up to the maximum dose used. The use of vetch intercropped with oats and ryegrass in areas is an alternative way to reduce the use of nitrogen fertilizer in corn grown in succession in livestock farming integration system, both for silage and for grain production, as well as providing an increase in nitrogen concentration in the tissue of maize plants.
125

Fenologia e produtividade de cultivares de videiras para suco em sistema agroecológico / Phenology and productivity of grapevine cultivars for juice in an agroecological system

Mariani, Josiane Aparecida 25 August 2017 (has links)
CAPES; UTFPR / A produção brasileira de uvas para elaboração de sucos vem se tornando uma importante alternativa de renda aos agricultores familiares, motivada pelo aumento no incentivo do seu consumo. Existem diversas cultivares adaptadas à produção de sucos, no entanto, algumas das cultivar recém-lançadas no mercado brasileiro ainda não foram suficientemente testadas em regiões de clima subtropical, a exemplo do Sudoeste do Paraná, justificando esse trabalho de pesquisa. Diante do exposto, objetivou-se com o presente trabalho avaliar o requerimento térmico, a qualidade e a produtividade das uvas de 15 cultivares: Bordô, BRS Carmen, BRS Lorena, BRS Magna, BRS Rúbea, BRS Violeta, Concord, Concord Clone 30, Isabel, Isabel Precoce, Moscato Embrapa, Moscato Bailey, Niagara Branca, Niagara Rosada e Seibel 5455,produzidas no sistema agroecológico em duas safras agrícolas, 2015/2016 e 2016/2017, em Dois Vizinhos, Paraná. As videiras foram implantadas em 2012, no sistema de condução de espaldeira. Para o estímulo da brotação das gemas foi utilizado calda sulfertilizante (sulfocálcica) a 5,0% + óleo mineral a 2,0%. Avaliou-se semanalmente a fenologia das plantas utilizando-se cinco estádios fenológico e obteve-se os requerimentos térmicos das videiras para distintos períodos do desenvolvimento das plantas, bem como o ciclo das mesmas. A exigência térmica foi definida pelo cálculo de acumulo de graus-dia (GD) desde o estádio de gema inchada até a colheita. Também foram realizadas avaliações de variáveis agronômicas a campo, como a determinação de componentes de rendimento, sendo número de cachos por planta, biomassa fresca de cachos, estimativa de produtividade (kg.planta-1 e t.ha-1). Também foram avaliados atributos químicos de qualidade dos sucos (mostos) obtidos, como: teores de sólidos solúveis (SS) em °Brix, pH, acidez titulável (AT) em percentagem e a relação entre os teores de SS/AT. As cultivares BRS Violeta, Isabel Precoce e Seibel 5455 são as mais produtivas. A cultivar Seibel 5455 possui maior requerimento término e ciclo mais tardio. A BRS Magna e BRS Violeta possuem menores requerimentos térmicos e ciclos mais precoces. As cultivares de videiras BRS Rúbea, BRS Violeta, Isabel, Moscato Embrapa, Moscato Bailey, Niagara Branca e Niagara Rosada apresentam teores de sólidos solúveis, pH e acidez desejáveis para a elaboração de sucos integrais de qualidade. O melhor ano-safra de cultivo foi 2016/2017 proporcionou as condições climáticas mais favoráveis à superação de dormência das gemas, brotação, floração e produção das videiras. / The Brazilian production of grapes for juice production has become an important income alternative for family farmers, motivated by the increase in the incentive of their consumption. There are several cultivars adapted to the production of juices, however, some of the cultivars recently launched in the Brazilian market have not yet been sufficiently tested in regions of subtropical climate, as in the southwestern region of Paraná, justifying this research work. In the present work, the objective of this study was to evaluate the thermal requirements, quality and productivity of the 15 grapes cultivar: Bordô, BRS Carmen, BRS Lorena, BRS Magna, BRS Rúbea, BRS Violeta, Concord, Concord Clone 30, Isabel, Isabel Precoce, Moscato Embrapa, Moscato Bailey, Niagara Branca, Niagara Rosada and Seibel 5455, produced in the agroecological system in two agricultural crops, 2015/2016 and 2016/2017, in Two Neighbors, Paraná state, Brazil. The vines were implanted in 2012, in the driving system of espaldeira. To stimulate bud buds, sulfer fertilizer solution (sulphocalcium) at 5,0% + mineral oil at 2,0% was used. The phenology of the plants was evaluated weekly using five phenological stages and the thermal requirements of the vines were obtained for different periods of the development of the plants, as well as the cycle of the same ones. The thermal requirement was defined by the calculation of day-degree accumulation (GD) since swollen buds stage to the harvest. Also evaluations of field agronomic variables were performed, such as determination of yield components, number of bunches per tree, fresh bunker biomass, yield estimate (kg.planta-1 e t.ha-1). Also, the quality of the juices (musts) obtained, such as: soluble solids (SS) in ° Brix, pH, titratable acidity (AT) in percentage and the ratio of SS/AT contents were evaluated. The cultivars BRS Violeta, Isabel Precoce and Seibel 5455 are the most productive. The cultivar Seibel 5455 has a higher end and later cycle requirement. BRS Magna and BRS Violeta have lower thermal requirements and earlier cycles. The cultivars of BRS Rúbea, BRS Violeta, Isabel, Moscato Embrapa, Moscato Bailey, Niagara Branca and Niagara Rosada grapevines have soluble solids, pH and acidity levels desirable for the production of quality whole juices. The best crop year was 2016/2017 provided the most favorable climatic conditions to overcome bud dormancy, budding, flowering and vines production.
126

Delimitation and analysis of homogeneous rainfall regions in the south-eastern Transvaal

Olivier, Jana 10 March 2014 (has links)
M.Sc. (Geography) / The 1982/1983 drought in the summer rainfall regions of South Africa highlighted the dependence of the agricultural sector as well as the general economy of the country on climatic vagaries. The results as indicated in this dissertation fonn a basis for the development of a yield prediction model for maize in the south-eastern Transvaal. The study consists of two parts, namely:- a) The delimitation of the south-eastern Transvaal into smaller homogeneous rainfall regions. b) An investigation of spatial and temporal rainfall patterns within each region and over the study area as a whole. a) The delimitation of the south-eastern Transvaal into smaller homogeneous rainfall regions: Various methods were investigated for this purpose and T-mode Principal Components Analysis with the subsequent clustering of component scores were found to be the most acceptable. b) An investigation of spatial and temporal rainfall patterns within each region and over the study area as a whole: Various parameters such as rainfall amount~ number of rain-days~ rainfall intensity~ seasonality and variability of rainfall were analysed. The presence of rainfall cycles and absence of linear trends were established. The orographic effect of the Eastern Escarpment on the spatial distribution of rainfall amount, frequency and intensity is clearly shown. Areas where conditions are less suitable for the dry-land cultivation of crops due to factors such as rainfall variability (in excess of 30%), steep slopes and relatively low rainfall intensity, were identified. Significant correlations were found between spring and late summer rainfall of a dry year
127

New insights on how changing hydroclimate might affect crop yields -- and a way to avoid the worst of it

Lesk, Corey Samuel January 2022 (has links)
Climate change threatens global food security by increasing extreme-weather shocks and reducing the productivity of major global crops. While recent research has highlighted the risk of rising extreme heat, comparatively little is known about how the intensity distribution of rainfall, and rainfall’s interactions with heat, influence global crops. Further, as the broader climate transition gains momentum, the industrial activities needed to mitigate and adapt to climate change will emit CO₂. These emissions remain unquantified and largely ignored in research and policy, and thus present an under-assessed risk to crops and society at large.This thesis advances the understanding of present and future agricultural risks from two aspects of hydroclimatic complexity: hourly rainfall intensity and temperature-moisture (T-M) couplings. Both aspects are expected to shift under climate change, with highly uncertain crop impacts. It further simulates the adaptation and mitigation emissions embedded in the broader climate transition, illuminating a previously under-appreciated benefit of enhance climate ambition. Climate warming is expected to intensify rainfall, decreasing the frequency of drizzle while boosting heavy and extreme events. I show that surprisingly heavy rainfall is optimal for US maize and soy yields, with yield loss due to drizzle and very extreme downpours. As a result, the future concentration of rainfall into fewer, heavier hourly events will benefit crop yields 2-3%, partly offsetting larger damages from warming. T-M couplings arising from land-air interactions and atmospheric circulation may shift under 21st Century warming, altering the likelihood of concurrent heat and drought extremes, with uncertain risks to crops. I demonstrate that maize and soy grown in regions with strong T-M couplings historically suffered enhanced crop sensitivity to heat. These couplings will strengthen over most of global croplands this century, worsening the impact of warming on crops by 5% globally, with large regional variations. The energetic demands of the broader climate transition – such as steel for wind turbines, and concrete for coastal barriers – will initially be satisfied by fossil fuels. I show that simulated mitigation and adaptation will emit 185GtCO₂ by 2100 under a transition path consistent with current policies (~2.7°C warming by 2100), equivalent to half the remaining carbon budget for 1.5°C. However, these emissions can be reduced by 90% under a 1.5°C transition path, a previously unidentified co-benefit of enhanced climate ambition.
128

The response of selected soil health variables to rainfed and irrigated maize-legume intercropping systems

Nong, Sello Simon January 2022 (has links)
Thesis (M.Sc. Agriculture (Soil Science)) -- University of Limpopo, 2022 / Soil health support crop production and answer to its sustainability and renewability. This study involved the use of under explored legumes in South Africa, Limpopo under maizelegume intercropping systems as a strategy to mitigate soil quality deterioration. The study was conducted at University of Limpopo (Syferkuil) and University of Venda (UNIVEN) Experimental farms during 2020/2021. A split plot experiment, with the main factor comprised of water regimes (irrigation and rainfed) and second main factor included cropping systems (Intercropping and monocropping). Five treatments comprised of 3 monocrops (Maize, Chickpea, and Mungbean) and 2 intercrops (maize-chickpea and maize-mungbean) replicated three times. Data collected from the soil before planting and after maturity were pH, Electrical conductivity (EC), particle size, bulk density, aggregate stability, organic matter (OM), organic carbon (OC), phosphorus (P), ammonium (NH4-N), nitrate (NO3—N), soil active carbon (SAC), and potentially mineralizable nitrogen (PMN). Plant parameters collected during vegetative and flowering stage included plant height, chlorophyll content, plant vigour, and leaf area index. All data was subjected to descriptive statistics and analysis of variance using GenStat software. Significant effect (p<0.05) was observed between treatments on soil pH (KCl), OM, organic carbon (OC), and ammonium (NH4) at Syferkuil Farm. Also, interaction between water regimes and cropping systems affected NH4 and pH (KCl). Cropping systems had significant effect (p<0.01) on pH (H2O), OM, OC, P, NH4, and NO3 at UNIVEN. Interaction between water regimes and cropping systems affected (p<0.01) pH (H2O), P but no significant effect was observed on OC, NH4, and NO3. Cropping systems and interaction at both locations did not affect particle size, bulk density, aggregate stability, EC, SAC, and PMN. Pure stands of maize and legumes had greater plant height, plant vigour, and chlorophyll content whereas intercrops had greater LAI. The results at both locations revealed that legume intercropping systems improved soil health variables without posing negative feedbacks and hence can be used to boost soil functioning. Keywords: Soil health, maize-legume intercropping, soil quality / National Research Foundation (NRF)
129

Simulation of irrigation requirements for Parana State, Brazil

Faria, Rogério Teixeira de January 1993 (has links)
No description available.
130

Seed treatment of maize, sorghum and sunflower with effective micro- organisms

Van Tonder, Nicolaas Christiaan Petrus January 2012 (has links)
Thesis (M. Tech. Agriculture) -- Central University of Technology, Free state, 2012 / A series of incubation studies and greenhouse experiments were conducted to evaluate the use of EM seed treatments, at different application levels, handling techniques and soil conditions on germination and seedling vigour of selected cultivars of maize, sorghum and sunflower. Two incubation studies were conducted to evaluate the germination and seedling vigour of maize, sorghum and sunflower seeds treated with M-EM from three different suppliers, multiplied at two different ratios (1% and 3%) and diluted at three different levels (0.01%, 0.1% and 1.0%) compared to a control treated with pure water. Results revealed no significant differences under optimum germination conditions, while seedlings under cold stress indicated that M-EM treatments positively affected germination and seedling vigour compared to the control treatments. Two incubation studies were also conducted to evaluate the germination and seedling vigour of maize, sorghum and sunflower seeds treated with M-EM from three different suppliers, multiplied at two different ratios (1% and 3%) and exposed to the influences of irradiation and temperature fluctuation. From the results became clear that the correct storage and handling is essential in optimizing the effect of M-EM on seeds. Even though M-EM was exposed to irradiation and temperature fluctuation, M-EM still had positive effects on germination and seedling vigour. Pot experiments were conducted to determine the effect of EM as seed treatment, at different dilutions, on germination, seedling vigour and dry mass of maize, sorghum and sunflower at different planted depths. Germination were not affected by the M-EM treatment, while shoot length results indicated that seed treated with M-EM could have significant effect on seedling survival. A greater effect was visible on the shoot length of shallow planted seeds, than on deeper planted seeds. From the results no single company, ratio or dilution could be prescribed as paramount. To further investigate the effect of M-EM subjected to the influences of irradiation and temperature fluctuation; maize, sorghum and sunflower seeds were treated with M-EM from three different suppliers, multiplied at two different ratios (1% and 3%) and exposed to the influences of irradiation and temperature fluctuation and planted in soil. M-EM treatments only benefited the germination of deeper planted sorghum seeds compared to the control treatments. The shoot lengths of deeper planted maize and sunflower seed were positively increased by the M-EM treatments while also resulting in significant results for the overall shoot length of sorghum. The third pot study was conducted to determine the influence of EM as a seed treatment on maize, sorghum and sunflower planted in three different soils, namely: sterilized soil, soil treated with M-EM and Fusarium containing soil. Germination and seedling vigour results of the sterilized and M-EM treated soil revealed to be superior to that of the Fusarium containing soil. From the results was concluded that M-EM treatments will probably improve early seedling growth of maize, sorghum and sunflower compared to untreated seed and that M-EM seed treatment and a pre-plant EM soil treatment might assist seeds in unfavourable germination and growth conditions.

Page generated in 0.2742 seconds