Efeito do déficit de água sobre a produção do feijoeiro (Phaseolus vulgaris L.).

Abstract

This work was conducted to study the phenological response of beans (Phaseolus vulgaris L., cultivar IPA-74-19) to water stress, and to study the drought tolerance capa city, At the Bebedouro Experimental Station .EMBRAPA, Petrolina, PE., two experiments were setted up using randomized block designs with 9 trataments and 3 replicates.The first experiment had water stress periods inspecific stages of plant growth, while the other experiment had different numbers of water stress days starting at the begining of flowering. In all the treatments, the irrigation was maintained at optimum level before and after a water stress period. At harvest, data for grain yield, number of pods per plant, and grains per pods were obtained. From the results, the following conclusions can be drawn. 1. In connection with phenological water stress - For grain yield, significative difference was found between treatments at 0.01 level.- For pods per plant data, significative difference was found between treatments at 0.05 level , whereas no significative difference was fóund between treatments for grains per pods. - Flowering was the most critical period to water stress,where a soil matric potential level of -5 bars produced 36.85% yield reduction. - At the begining of flowering, water stress of -7 bars of soil matric potential produced 20.49% yield reduction. - At the initial and later stages of fruitformation, soil water deficit of-2.7 bars caused 24% of yield reduction. 2. In çonnection with drought tolerance- For grain yield, significative difference was found between treatments at 0.01 level- For pods per plant, and grains per pods data significative differences were found between treatments at 0,05 and 0.01 leveis, respectively. - Yield reduction of 20% was observed when the crop was 14 days without irrigation during the flowering stage. After 17 and 20 days without irrigation, yield reductions of 38 and 52%, respectively, were observed. After 20 days, yield reductions remained constant until 29 days of water stress. - Variations in soil water content for the 0-30 cm layer followed an hyberbolic function on , with -0.2; -0.7; -0.9; -1.7; -3.8; -6.4; -8.2; -10, and -12,2 bars of matric potential for 3, 8, 11, 14, 17, 20, 23, 26 and 29 days of water stress, respectively.