Aspectos fisiológicos e de produção do feijoeiro submetido a estresse por déficit hídrico

Abstract

Cowpea beans (Vigna unguiculata) is of African origin and introduced in Brazil by Portuguese colonists in the second half of the 16th century. It is cultivated in more than half of the Brazilian states, in a regime of three harvests. It is very important for food security, due to the presence of proteins and carbohydrates, in addition to its production generating employment and income in drier regions of the country. It’s a plant resistant to the stress caused by water deficit, a factor that benefits its third crop production, when the rains have already stopped. The aim of this study was to analyze the influence of water stress stress on the physiology and production of the cowpea crop. For this, four cultivars of cowpea beans, cultivated in the state of Paraíba, were selected, namely, Corujinha, Macaíba Branca, Roxinho and Sempre Verde. We sought to know the minimum need for irrigation and its influence on physiological variables such as net photosynthesis values, stomatal conductance, transpiration, internal carbon, water use efficiency and instantaneous carboxylation efficiency and on production variables such as number of pods ripe seeds, number of seeds, number of seeds per mature pods and weight of 100 seeds. The experimental design completely randomized. The water deficit caused a reduction in gas exchange evaluated from the net photosynthetic rate, stomatal conductance, internal CO2 concentration, transpiration, vapor pressure deficit, instantaneous water use efficiency and carboxylation, throughout phenological development and in all the genotypes. Lower plant height observed, with a significant reduction in flower fixation, pod production and grain filling. In the initial growth phase, tolerance to water deficit observed, but the deviation from the mean by the Roxinho phenotype was visible, when compared to the other phenotypes, characterizing a delay in its physiological development in relation to the other phenotypes. On the other hand, the Evergreen phenotype showed greater tolerance to water stress, resulting in higher productivity.