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.
Highlights
Soybean plants are affected by various abiotic stresses such as high salinity, low temperatures, mineral element toxicity, drought and others (Ferreira et al, 2020; Escalera et al, 2021; Gontijo et al, 2021; Pimentel et al, 2021)
According to Food and Agriculture Organization of the United Nations (FAO) (2015) the international research community should be aware to solutions that reduce the problems caused by abiotic factors in agriculture, including drought
According to the classification of experimental precision proposed by Gomes (1990), the values found for the experiments of physiological parameters and activity of antioxidant enzymes, obtained a medium experimental precision (10.7% and 20.02%, respectively), which is favorable, as it strongly attests to the inferences raised
Summary
Soybean plants are affected by various abiotic stresses such as high salinity, low temperatures, mineral element toxicity, drought and others (Ferreira et al, 2020; Escalera et al, 2021; Gontijo et al, 2021; Pimentel et al, 2021). Drought or continuous water deficiency is one of the most important factors affecting growth, development, survival and productivity of the crop (Manavalan, Guttikonda, Tran, & Nguyen, 2009; Fried, Narayanan, & Fallen, 2019). According to Food and Agriculture Organization of the United Nations (FAO) (2015) the international research community should be aware to solutions that reduce the problems caused by abiotic factors in agriculture, including drought. They suggest that one of the possible solutions is the development and use of new plant cultivars. The development of new cultivars tolerant to abiotic stresses, to water stress, has a greater importance in soybean breeding programs. The use of biotechnological tools has favored more detailed information involving the identification, interaction and quantification of genes involved in Soybean water deficit tolerance (Langridge & Reynolds, 2015; Cilliers, Heerden, Kunert, & Vorster 2018; Khan et al, 2018; Ye et al, 2020)
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