Produção de algodoeiros de fibra naturalmente colorida sob estresse hídrico em diferentes fases fenológicas.

Abstract

The interest in the cultivation of colored cotton in Brazil, which emerged in the Northeast region, by family farmers, took the advantage of being produced in a consortium with subsistence crops such as beans, maize and sesame. However, in the semiarid region of northeastern Brazil, cotton is often subjected to different durations and intensities of water deficit in the soil, mainly due to the scarcity or lack of rainfall characteristic of this region. In this sense, the objective was to evaluate the morphophysiology and production of naturally colored cotton genotypes under water deficit at different stages of plant development. The plants were conducted in lysimeters in a greenhouse, at the Center for Agrifood Science and Technology belonging to the Federal University of Campina Grande, in the city of Pombal-PB. The design used was a randomized block in a 3x3 factorial scheme, with three colored fiber cotton genotypes (BRS Rubi, BRS Topázio and Safira) irrigated under water deficit where the volume obtained was determined by the water balance of the least applications. Volume drained from previous irrigation during the three stages of crop development (vegetative, flowering and fruiting) available in nine treatments, with three replications and three plants per plot, totaling 81 plants. Physiological characteristics, growth, phytomass and production components were evaluated. The water deficit significantly reduced the gas exchange of the cotton genotype during the vegetative phase and the flowering phase was the least affected for all variables. Cotton plants reduced their growth, pigment levels, root/shoot ratio and production components when subjected to water stress during flowering and fruit fruiting. Among the genotypes, BRS Topázio is the most tolerant to water deficit (40% of the ETR) during the vegetative phase for the cotton lint mass, average boll weight and seed production.