Gas exchange and growth of colored cotton subjected to saline stress and foliar application of H2O2

Abstract

Cotton is one of the main agricultural crops in the world, being widely cultivated in the Brazilian Northeast. However, its exploration in the semi-arid region of Northeastern Brazil is limited by the salinity of the irrigation water, making it necessary to adopt strategies capable of mitigating the effects of saline stress, such as the foliar application of hydrogen peroxide. The objective of this study was to evaluate gas exchange and growth of naturally colored cotton fiber ‘BRS Jade’ subjected to saline stress and foliar application of hydrogen peroxide. The experiment was carried out under field conditions at the Center for Agro-Food Science and Technology of the Federal University of Campina Grande, Pombal, Paraíba, Brazil. The experimental design was in randomized complete block with a 5 × 5 factorial scheme, consisting of five levels of irrigation water electrical conductivity – ECw (0.3, 2.0, 3.7, 5.4, and 7.1 dS m^-1) and five concentrations of hydrogen peroxide – H₂O₂ (0, 25, 50, 75, and 100 μM). The salinity of the irrigation water reduced gas exchange and the growth of ‘BRS Jade’ cotton. Foliar application of H₂O₂ at concentrations of 62.5 and 50 μM promoted a beneficial effect on stomatal conductance and transpiration of cotton plants under ECw of 0.3 dS m^-1. The internal CO₂ concentration and CO₂ assimilation rate were higher in plants grown without H₂O₂ application at the ECw levels of 0.3 and 3.7 dS m^-1, respectively. The 100 µM concentration of H₂O₂ stimulated the growth in plant height and leaf area of the cotton plant ‘BRS Jade’ under conditions without saline stress (ECw 0.3 dS m^-1).