Physiological alterations and enzymatic evaluation of soybean cultivars under water deficit

Abstract

Drought is one of the main abiotic factors limiting agricultural productivity, capable of having a major impact on the yield of most crops. The knowledge of the physiological and biochemical mechanisms that differentiate resistance and susceptibility to water deficit among soybean strains can be used in the generation of more tolerant cultivars. In this sense, the objective of this study was to characterize physiologically, two soybean cultivars with different patterns of tolerance to drought in the field, by determining photosynthetic rates, lipid peroxidation levels and antioxidant enzyme activity under three levels of water potential. Upon reaching the V4 development stage, the irrigation of the plants was suspended and three data collection were performed: full irrigation (control); moderate water deficit (Ψ = -1.5 ± 0.2 MPa) and severe deficit (Ψ = -3.0 MPa ± 0.2 MPa). Variations in perspiration rate, stomatal conductance, as well as decrease in photosynthetic rate were significant between the two cultivars, where the water potentials in cultivar BR 16 anticipated on average two days achieving the same water potentials in Embrapa 48 cultivar, thus presenting better efficiency in water use. In addition, the increased activity of enzymes and lipid peroxidation were more significant in the cultivar BR 16, demonstrating that this cultivar is less tolerant to drought than Embrapa 48 cultivar, corroborating to agronomic data previously found in the field.