Exogenous superoxide dismutase alleviates drought stress in cotton genotypes1

ABSTRACT In drought-tolerant plants, adverse effects caused by water deficit can be mitigated by antioxidant enzymes, which activate the plant’s defense mechanisms. This study aimed to evaluate the mitigating effect of exogenous superoxide dismutase (SOD) supplementation on cotton plants subjected to drought stress. Four cotton genotypes (BRS Seridó, FM 966, FMT 705 and CNPA 7MH) were grown in a greenhouse and evaluated under the following treatments: control (daily irrigation), drought stress (plants subjected to 6 days without irrigation) and drought stress with exogenous SOD supplementation at concentrations of 11, 22 and 33 µg mL-1. The experimental design was a randomized block arrangement, in a 4 × 5 factorial scheme, with four replications. Plant growth, biomass accumulation and gas exchange parameters were evaluated. Overall, the exogenous SOD supplementation at 33 µg mL-1 effectively mitigated the adverse effects of drought stress on cotton growth and gas exchange, with a more pronounced response observed for the drought-sensitive genotypes.