Atenuação do estresse salino em genótipos de algodão colorido pela aplicação de peróxido de hidrogênio.

Abstract

Cotton is a socioeconomically important crop for Brazilian agribusiness, as it is the main fiber supplier for the textile industry. Its naturally colored fiber genotypes have received attention from the industry and producers, as they do not require fiber dyeing. However, the advancement of cotton farming in semi-arid regions may be limited by the salinity of irrigation water and the scarcity of low-salt water. Thus, the adoption of cultivation strategies, such as exogenous applications of hydrogen peroxide and the use of salinity tolerant genotypes, may enable the use of saline water in irrigation. In this perspective, the objective of this research was to evaluate the morphophysiology, production and fiber quality of colored cotton genotypes irrigated with saline water and foliar applications of hydrogen peroxide. The research was carried out in a greenhouse under a randomized block design, in a 4 × 3 × 2 factorial arrangement, referring to four concentrations of hydrogen peroxide – H2O2 (0, 25, 50 and 75 µM), three cotton genotypes (BRS Rubi, BRS Verde and BRS Topázio) and two electrical conductivities of irrigation water - CEa (0.8 and 5.3 dS m-1), with three replications. Foliar application of 50 µM of hydrogen peroxide attenuated the saline stress in cotton plants BRS Rubi under irrigation with water of 5.3 dS m-1. Irrigation with 0.8 dS m-1 water associated with foliar application of 50 µM of hydrogen peroxide promoted the highest levels of photosynthetic pigments and maximum fluorescence, variable fluorescence and quantum efficiency of PSII from the cotton plant BRS Rubi. Irrigation with water of 0.8 dS m-1 together with foliar application of 75 µM of hydrogen peroxide promoted cottonseed mass, plume mass, resistance, micronaire index, maturity of BRS Topázio cotton, at 130 days after planting. sow. In addition, the 5.3 dS m-1 water associated with 25 µM applications can be used to irrigate the BRS Topázio cotton plant, as it promotes greater production and fiber quality.