Resposta produtiva do feijão carioca (Phaseolus vulgaris L. TAA DAMA) sob déficit hídrico em diferentes fases fenológicas
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Data
2021-07-30
Autores
Santos, Rafaela Magalhães
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Universidade Estadual Paulista (Unesp)
Resumo
O Brasil está entre os dez países que mais irrigam no mundo. Tendo em vista que somente as águas pluviais não são suficientes para suprir a demanda hídrica das culturas, pois os índices pluviométricos apresentam grande desuniformidade de distribuição, a irrigação apresenta-se como ferramenta fundamental para a segurança hídrica no campo. Estudos sobre o uso racional da água na irrigação são de suma importância, tendo em vista a economia de água, energia e para um bom desempenho de produtividade agrícola. Nesse sentido, a determinação dos coeficientes de resposta hídrica (Ky) surge como alternativa para realizar o manejo da irrigação. O objetivo deste trabalho foi determinar os valores de Ky em diferentes fases fenológicas da cultura do feijão carioca nas condições de Botucatu-SP. Para tanto, foi instalado um experimento na Fazenda Lageado, no Departamento de Solos e Recursos Ambientais em casa de vegetação. O delineamento experimental foi em blocos casualizados, constituído por 4 tratamentos e 12 repetições. Os tratamentos consistiram na aplicação de déficit hídrico controlado, na tensão de 70kPa, representado 50% da capacidade de água disponível (CAD), em diferentes estádios fenológicos: T1: controle (não houve déficit hídrico em nenhum momento); T2: estádio vegetativo; T3: estádio de floração e T4: estádio de enchimento de grão. Foram analisados área foliar; altura de planta; diâmetro do caule; leitura indireta de clorofila; trocas gasosas: assimilação líquida de CO2 (fotossíntese líquida), condutância estomática, concentração interna de CO2, transpiração, eficiência do uso da água, matéria seca, matéria fresca e produtividade. Os dados obtidos foram submetidos à análise de variância e ao teste Tukey a 5% de probabilidade. Foi possível concluir que a fase de enchimento de grão, aos 82 dias após plantio, foi a fase que obteve a maior perda de produtividade na cultura, e consequentemente a taxa de evapotranspiração inferior à taxa potencial, acarretando em um decréscimo de 47,84% de produtividade com relação ao controle. Assim os valores de Ky nas fases vegetativa, floração e enchimento de grãos foram 1,32, 1,63 e 1,85 respectivamente.
Brazil is among the ten countries that most irrigate in the world. Considering that only rainfall is not enough to supply guarantee water crop demand, since the rainfall indexes present a great uneven distribution, irrigation presents itself as a fundamental tool for water security in agriculture. Studies on the rational irrigation water use are of paramount importance for a good productivity performance, while at the same time ensuring water and power costs. Savings in this sense, a determination of water response coefficients (Ky) appears as an alternative to carry out irrigation management. Thus, the objective of this work was to determine the Ky values for different bean phenological phases at Botucat-SP. An experiment was installed in a greenhouse at Fazenda Lageado, Department of Soils and Environmental Resources. The experimental design was randomized blocks, consisting of 4 treatments and 6 repetitions. The treatments were application of water control deficit tension of 70kPa, represented 50% of the available water capacity, a different phenological stages: T1: control (there was no water up to deficit at any time); T2: vegetative stage; T3: flowering stage; T4: grain filling stage. It were measured leaf area; plant height; stem diameter; indirect chlorophyll reading; gas exchange: net CO2 assimilation (liquid photosynthesis), stomatal conductance, internal CO2 concentration, transpiration, dry matter, fresh matter and productivity. The collected data had an analysis of variation and Tukey test at 5% probability. It was possible to conclude that the grain filling stage, at 82 days after sowing, was the phase that obtained the greatest loss of productivity and, consequently, an evapotranspiration rate lower than the potential rate, resulting in a 47.84% decrease in productivity compared to the control. Thus, Ky values in the vegetative, flowering and grain filling stages were 1.32, 1.63 and 1.85 respectively.
Brazil is among the ten countries that most irrigate in the world. Considering that only rainfall is not enough to supply guarantee water crop demand, since the rainfall indexes present a great uneven distribution, irrigation presents itself as a fundamental tool for water security in agriculture. Studies on the rational irrigation water use are of paramount importance for a good productivity performance, while at the same time ensuring water and power costs. Savings in this sense, a determination of water response coefficients (Ky) appears as an alternative to carry out irrigation management. Thus, the objective of this work was to determine the Ky values for different bean phenological phases at Botucat-SP. An experiment was installed in a greenhouse at Fazenda Lageado, Department of Soils and Environmental Resources. The experimental design was randomized blocks, consisting of 4 treatments and 6 repetitions. The treatments were application of water control deficit tension of 70kPa, represented 50% of the available water capacity, a different phenological stages: T1: control (there was no water up to deficit at any time); T2: vegetative stage; T3: flowering stage; T4: grain filling stage. It were measured leaf area; plant height; stem diameter; indirect chlorophyll reading; gas exchange: net CO2 assimilation (liquid photosynthesis), stomatal conductance, internal CO2 concentration, transpiration, dry matter, fresh matter and productivity. The collected data had an analysis of variation and Tukey test at 5% probability. It was possible to conclude that the grain filling stage, at 82 days after sowing, was the phase that obtained the greatest loss of productivity and, consequently, an evapotranspiration rate lower than the potential rate, resulting in a 47.84% decrease in productivity compared to the control. Thus, Ky values in the vegetative, flowering and grain filling stages were 1.32, 1.63 and 1.85 respectively.
Descrição
Palavras-chave
Coeficiente de resposta hídrica (Ky), Evapotranspiração, Tensiômetria, Hargreaves samani, Produtividade, Water response coefficient (Ky), Evapotranspiration, Tensiometer, Yield