Estratégias de manejo da irrigação em fases fenológicas do feijão vigna sob adubação potássica.

Abstract

In subtropical and tropical regions, Vigna beans are considered one of the most important and strategic food sources. In the Northeast region, due to seasonal changes in rainfall, with changes in the availability of water in the soil, in this region the proper management of resources is essential in order to guarantee the sustainability of the production system. Thus, the objective of the present work was to evaluate the gas exchanges and production components of Vigna cv. BRS Marataoã cultivated under water deficit management strategies and potassium fertilization. A randomized block statistical design was used, in a 5 × 5 factorial scheme, with three replications, with the treatments being defined according to the five potassium fertilization doses (50, 75, 100, 125 and 150% of K2O) associated with five water deficit management strategies in the different phenological stages of the crop. The dose of 150% K2O, in Vigna bean plants, intensifies the negative effects of water stress, reducing stomatal conductance, pod length, pod weight and total number of beans in all phenological stages. The irrigation management of Vigna bean plants, with 50% of the ETr, did not cause significant difference for the instantaneous efficiency in the use of the water between the studied phenological phases. Vigna beans fertilized with 50% of the recommended dose of K2O had the lowest CO2 assimilation rates when subjected to water stress in the phenological stages.