Tolerância de Vigna unguiculata à salinidade sob estratégias de irrigação em dois ciclos cultivos.

Abstract

Water is one of the main limiting factors for the growth and development of crops, which may affect the yield of plants, notably Vigna beans, justifying the use of irrigation. When cultivated in areas of the semiarid region, characterized by waters with high levels of salts, attention should be paid to the use of genotypes that are more tolerant to salt stress, in addition to adequate irrigation strategies, if they are with saline waters, in order to ensure sustainability of the production system. In this work, the objective was to evaluate, in two consecutive cultivation cycles, the tolerance of two genotypes of Vigna beans to saline stress applied in different phenological phases, analyzing the existence of epigenetic regulations in the second generation of the plants. The work was carried out in the field, with two experiments, the first one between September and December 2018 and the second experiment was conducted between August and November 2019, at the Rolando Rivas Experimental Farm, belonging to the Federal University of Campina Grande, UFCG, Campus de Pombal , PB, located in the city of São Domingos, PB. In the first experiment, the factors consisted of three genotypes of Vigna beans submitted to seven salinity management strategies, varying the development stages of the plants. Combined these factors resulted in 21 treatments where the experimental design was in randomized blocks in a 7 x 3 factorial scheme, with four replications, totaling 84 experimental plots, whose experimental unit was composed of 60 plants. In the second experiment, irrigation management strategies resulted from the combination of phenological phases between the two cycles, using water with high salinity, alternating with water with low salt concentration. Two genotypes of Vigna beans were studied, submitted to ten salinity management strategies, resulting in a 10 x 2 factorial, with four replications, totaling 80 experimental plots, each experimental unit was composed of 60 plants. Growth, physiological and genotype production variables were analyzed. The data obtained were subjected to analysis of variance, 'F' test (p <0.05) and grouping test of means, ScottKnott (p <0.05) for the factor of irrigation management strategies and Tukey test, (p<0.05) for Vigna bean genotypes. The plants were more sensitive to salinity in the vegetative phase, reflected in the formation of phytomass in both cultivation cycles. The acclimatization was reflected in the gas exchange and fluorescence of chlorophyll a.