A memória ao estresse preserva a produtividade da soja?

Abstract

The intensification of drought events has significantly compromised soybean productivity, especially in regions subjected to climatic variability. In this context, the objective was to identify the importance of physiological memory to stress in the growth and grain production of soybeans. The experiment was conducted in a greenhouse at the State University of Goiás, using a completely randomized design composed of treatments with different continuous and discontinuous water deficit regimes, applied in one or two cycles, in addition to a fully irrigated control treatment. Water deficit reduced relative water content and promoted changes in vegetative growth. However, severe and moderate deficit treatments showed distinct responses, even under similar reductions in plant water status. The severe deficit treatment maintained greater leaf area and productive performance comparable or superior in some variables, such as 100-grain weight. Regarding biochemical responses, increases in total chlorophyll and carotenoid contents were observed, in addition to changes in the activity of antioxidant enzymes CAT, SOD, and POD. The relative maintenance of CAT activity under severe deficit suggests the participation of antioxidant mechanisms associated with drought tolerance. Multivariate analysis evidenced integration among morphophysiological, biochemical, and productive responses. The obtained results suggest the occurrence of physiological mechanisms compatible with acclimation processes and possible physiological memory in plants subjected to successive water deficits, reinforcing the adaptive potential of soybean under conditions of water variability.