Recuperação de genótipos de vigna ao estresse hídrico variando o estádio de desenvolvimento

Abstract

The bean Vigna is cultivated in the Brazilian Northeast, being an important source of food for the population. In the semiarid region, Vigna is one of the most important crops, mainly in cultivation by family farming. For its socioeconomic importance and need for research, this work was carried out, aiming to evaluate components of growth, development and production of four genotypes of the Vigna bean. The plants were grown in drainage lysimeters submitted to managments practices in distinct phases of the phenological cycle, varying the conditions of presoaking

of seeds, by evaluating the degree of plant recovery after ceased the stress factor. Genotypes: G1- BRS Itaim; G2 - BRS Cauamé; G3 - BRS Guariba; G4 - BRS Pajeú were used. Irrigation managements were: S0 - full irrigation throughout the cycle of the plants; S1- full water supplementation until the phase V3, when irrigation was suspended, until the appearance of the first flower bud, turning to irrigate until the end of the cycle; S2 - full water supplementation, until the phase R2, when the supply of water was suspended for 20 days, starting to irrigate again until the end of the cycle. Pre-soaking seeds: Eo - without soaking; E1- soaking in water during 8 hours, with sowing then; E2 - soaking during 8 hours followed by drying in the shade by 3 hours and then sowing. In factorial scheme, the factors resulted in 36 treatments, on split plot, with 4 replications. In plots were distributed the genotypes (G) and the managements of irrigation (S) and in sub plots the conditions of pre-soaking (E). Germination, growth, physiological and production variables and degree of recovery of the genotypes to water stress were evaluated. The treatment of presoaking did not affect the germination and emergency variables. The length of the hypocotyl and

of the epicotyl

were not influenced by the treatment of pre-soaking. The water stress damage is most evident in the gas exchange (transpiration and photosynthesis), and these variables are useful tools in evaluating the effects of stress of water in Vigna. There was damage to the photosystem II, caused by water deficit. The components of production and dry matter were more affected by stress during the reproductive phase. The genotype`BRS Pajeu` is the most tolerant to water stress and the ‘Guariba’ is the most sensitive one, especially in situations of water shortage.