Cultivo de algodoeiro BRS 286 inoculado com Azospirillum Brasiliense e submetido ao estresse salino.

Abstract

Water scarcity and high levels of salinity in irrigation water limit irrigated cotton cultivation in the semiarid region of northeastern Brazil. Therefore, it is necessary to adopt strategies that make the production system viable. In this sense, the inoculation of seeds with Azospirillum brasilense can help in the tolerance of plants to salt stress. In this context, the objective of this study was to evaluate the growth, phytomass accumulation and production of BRS 286 cotton irrigated with water of different salinity levels and inoculated with Azospirillum brasilense. The research was conducted in a protected environment (greenhouse) in drainage lysimeters. The treatments resulted from the combination of two factors: five levels of electrical conductivity of irrigation water - ECw (0.4; 3.1; 4.1; 6.1 and 7.1 dS m-1 ) associated with inoculation or not of cotton seeds with Azospirillum - IA (with and without inoculation), distributed in a completely randomized design, in a 5 × 2 factorial arrangement, with six replications, totaling sixty experimental units. Irrigation with water with electrical conductivity above 0.4 dS m-1 negatively affected the growth of BRS 286 cotton, at 110 and 140 days after sowing. However, inoculation with azospirillum favored the growth in stem diameter, number of leaves and leaf area; The accumulation of phytomass in the cotton plant was reduced with the increase in the electrical conductivity of the irrigation water. Being the variable dry leaf phytomass the most affected by salt stress; The number of bolls, the number of seeds, the seed mass and the cotton lint mass were drastically reduced by irrigation with saline water, reaching the lowest values under irrigation with ECw of 7.1 dS m-1 ; Inoculation with Azospirillum neither influenced nor mitigated the deleterious effects of the salinity of the irrigation water on the production components of cotton BRS 286; BRS 286 cotton can be classified as moderately sensitive according to the criterion of reduction in relative yield.