Genetic parameters related to gas exchange and production components in cowpea populations under drought

Drought is the main abiotic stress in many crops which is affected by the high number of genes involved and intense genotype × environment interactions. However, gas exchange represents a new approach with a high detection efficiency. This study aims to evaluate genetic parameters; determine population performances based on data linked to gas exchange and production components; and determine whether gas exchange is useful for selecting Vigna unguiculata populations that are drought tolerant using six populations from crosses between BR3-Tracuateua (sensitive to drought) and Pingo de ouro-1–2 (drought-tolerant). Our results revealed that production components, mainly grain production, water-use efficiency and carboxylation instantaneous efficiency, and gas exchange presented higher means and variances in the F2 generation. In general, the additive variances were higher than the dominance variances, suggesting intense additive allelic interactions for the evaluated characteristics. Gas exchange is efficient for selecting cowpea populations with tolerance to drought because they present high correlation coefficients with production components, such as between grain production and the carboxylation instantaneous efficiency (0.91), as well as grain production and water-use efficiency (0.89).