Variações na morfofisiologia e no rendimento do feijoeiro submetido a diferentes lâminas de irrigação.

Abstract

The research work was conducted at the Experimental Station of Lagoa Seca, located in the Empresa Estadual de Pequisa Agropecuaria da Paraiba, EMEPA-PB, with the objective of identifying the consequences of soil moisture content, in the growth variables, yield components and components of water stress, in the bean (Phaseo/us vulgaris L.) crop. The statistical design used was the randomized blocks, with four treatments and four replications. The treatments were based on different irrigation levels: 80, 160, 320 e 140,2 mm, distributed in the different phynological phases of the crop and based on the results of the previous studies and in the soil humidity. The effects of the different irrigation regimes were evaluated by means of the distribution of the phytomass, total phytomass, leaf area, leaf area index, net assimilation rate, leaf area ratio, respiration, yield components and variations in the components of water stress. The growth variables showed differentiated values in response to the water treatments employed. The respiration was insensitive to the water stress, strengthening condition of the bean crop in exhibiting the physiological responses that result in the development of adaptation mechanisms. The other growth variables had variation directly proportional to the employed treatments, presenting higher values in plants supplied with higher levels of irrigation. The increases in the yield components were also higher in plants with higher supply of water. Values of water stress components, obtained through the infrared thermometer, showed a good consistence of results, with larger canopy temperatures in plants with moisture restrictions. The differences between the canopy and air temperatures presented positive values that indicate the occurrence of water stress when the crop was submitted to lower supply of water. The stress degree day index evidenced increased stress levels during the whole cycle of the crop with limited water supply. The results indicated that the growth variables and the yield components are related to the components of water stress, determining morphop hy si o logical variations of the bean crop, in its different phenological stages.