AGRONOMIC AND PHYSIOLOGICAL INDICATORS FOR SELECTION OF WATER RESTRICTION-TOLERANT GRAIN SORGHUM GENOTYPES

Selection of tolerant plants is essential to meet the challenges of food production. The objective of this study was to evaluate agronomic and physiological characteristics as indicators for the selection of water restriction-tolerant grain sorghum genotypes. The experiments were conducted in 2014, 2015 and 2016. Two trials were installed in each year, one subjected to full irrigation and the other to water restriction. In the first one, irrigation was performed periodically, at a 2-day interval, to maintain soil moisture close to field capacity. In the second one, irrigation was suspended in the pre-flowering period, keeping the restriction for 30 days. Four sorghum genotypes were used: 9503062 and 9618158 - drought sensitive (S); 9910032 and P898012 - drought tolerant (T). The experimental design was randomized blocks with four replicates. Stomatal conductance, relative chlorophyll content, photosynthetically active leaf area, plant height and yield were evaluated. Joint analysis of the experiments subjected to full irrigation and water restriction of the three years was performed. Under water restriction it was not possible to distinguish between sensitive and tolerant materials. The characteristics evaluated in this experiment did not allow a conclusive distinction between tolerant and sensitive genotypes.