Trocas gasosas e produtividade em acessos de feijão-caupi do Banco Ativo de Germoplasma da Universidade Federal do Ceará

Abstract

Cowpea is a legume of African origin of great importance for food and employment generation and income for the tropical and subtropical regions of the world, mainly in the North and Northeast regions where its cultivation is concentrated. Water stress is one of the most impacting factors affecting plant growth and physiological responses, due to the decrease in the rate of photosynthesis, which is related to the limitation of gas exchange, due to the closure of the stomata. The objective of this study was to characterize and evaluate the physiological parameters and productivity from the gas exchange evaluations of 59 genotypes of cowpea under rainfed conditions, identifying the genotypes that are more tolerant to drought. The experiment was conducted in the area of cowpea multiplication of the Federal University of Ceará. Two gas exchange evaluations were carried out, one in the vegetative phase and the other in the reproductive phase. The variables were the photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), US water efficiency and efficiency EiC carboxylation flash. The experimental design was the completely randomized (DIC) in a factorial scheme 59 x 2, with 59 genotypes and 2 phenological stages, with 3 replicates. The experimental results were submitted to analysis of variance and the means compared by the Scott Knot test at 5% significance. The results showed that, in relation to the variable photosynthesis (A), stomatal conductance (gs) and productivity, accesses CE693, CE701 and CE880 obtained better results. In the transpiration variable (E) the accessions CE693, CE880 and CE570 obtained better results in the vegetative phase and accesses CE735, CE880 and CE659 in the reproductive phase. In relation to US, accessions CE109, CE659 and CE735 obtained better results in the vegetative phase, and accessions CE701, CE693 and CE109 had better results in the reproductive phase. In the variable instantaneous carboxylation efficiency (EiC), there was no significance between the phases. Thus, it was possible to conclude that, in general, CE880, obtained better results, being the most suitable for the semiarid region, then accesses CE701, CE693, CE735.