Genetic analysis of rice genotypes with contrasting response to aerobic conditions

Climate change and emerging water scarcity have seriously threatened the rice production systems which necessitate developing drought tolerant genotypes for ensuring food security. A trial was conducted to explore the genetic divergence among rice genotypes with an ultimate aim to sort out drought tolerant genotypes with high grain yield potential. The trial was comprised of seven rice genotypes along with their twenty one hybrids grown under aerobic conditions. The results revealed that hybrids of Azucena x Giza177 and Azucena x Giza179 remained superior by recording the maximum leaf diffusive resistance, leaf transpiration rate, and grain yield. In contrast, IRAT112 x N22 and IRAT112 x Azucena hybrids exhibited the lowest stomatal conductance. Besides rice hybrids, three parents N22, Azucena and Giza179 were identified as promising general combiners in terms of drought tolerance, physiological robustness and better grain yield components and thus these might be recommended as potent candidates for future breeding programs to increase drought tolerance. Additionally, grain yield per plant was positively correlated with leaf diffusive resistance, net photosynthesis rate, CO2 concentration, photosynthetic active radiation, panicles numbers, 100-grain weight, and fertility percentage, while it had negative association with stomatal conductance, leaf transpiration rate, leaf temperature, and leaf rolling. Moreover, the crosses of Azucena x Giza177, IRAT 112 x Azucena, IRAT 112 x N22, and Azucena x Giza179 showed good SCA effects and significant heterosis indicating that the hybrid combinations could be an introgression to drought.