Identification of Drought Tolerant Rice Genotypes Based on Morpho-Physiological and Yield Traits Under Normal and Drought Stress Conditions

Abstract

Water shortage is a serious climatic factor that drastically limits rice productivity. Thereupon, the development of better adapting rice genotypes under water deficit stress is imperious to maintain rice yield to ensure food security worldwide. The current study focused on genetic variability of morpho-physiological traits of rice to discover relationships between morpho-physiological and yield contributing traits under drought stress conditions in 24 rice genotypes during 2019 and 2020 seasons. Results showed highly significant mean squares of combined analysis for treatments and environment of all studied traits under normal and drought stress conditions. Results reported that the earliest rice cultivars were Giza177 and Giza179; however, the highest yield and its components traits were detected for Giza179, followed by Giza178, Sakha101 and Sakha108 under normal and water deficit conditions; moreover, generally, PCV was higher than GCV for all studied traits. High heritability coupled with high genetic advance was noted for plant height and relative water content under normal and drought conditions, suggesting a preponderance of additive gene action in expressing these traits that could be improved by selection in early segregating generations. While, high heritability coupled with moderate genetic advance was noticed for duration, grain yield/plant and harvest index under both conditions. Giza179 and Giza178 showed the best values for drought tolerance and were produced from same genetic background. Moreover, grain yield/plant showed a highly significantly positive correlated with panicle length, number of panicles/plant, panicle weight and 100-grain weight under normal and water deficit conditions; moreover, these traits were the main components of grain yield, so any selection based on these traits may lead to enhancement in grain yield. As a result, Giza178 and Giza179 varieties can be introduced as donors in breeding programs to tolerate water shortages to improve morphological and yield characteristics.

Genetic Variability Parameters for Yield and Related Traits in Rice (Oryza sativa L.) under Irrigated Normal and Drought Stress Condition

“…In our research, traits such as leaf proline content, flag leaf area, fresh shoot weight and spikelet fertility exhibited high heritability and high GAM. The outcomes inferred were in tune with the results observed by Ganapathy et al [10]; Mina et al [9]; [22][23][24] suggesting least amount of environmental influence indicating the prevalence of the additive gene effects. As a consequence, under water stress conditions, genotypes can be altered and chosen for these features to improve drought tolerance.…”

Studies on Combining Ability and Heterosis for Some Traits of Root and Yield Characters of Some Rice Genotypes Under Normal and Water Deficit Conditions

“…Significant and highly significant mean square estimates were recorded for genotypes, parents, crosses and the interaction among them for all these traits under both water deficit and normal conditions, except root/shoot ratio under both conditions for all sources of variance, chlorophyll content and relative water content under water deficit and 1000-grain weight under normal condition for parents vs. crosses which were insignificant. These results agree with those obtained by Saleem et al, (2010), El-Hity et al, (2015, Daher (2018), Abdelaty et al, (2022) and Hassan et al, (2023). Estimates of both general (GCA) and specific combining ability (SCA) variances were found to be highly significant for all root traits, yield and its components and some physiological traits under both water deficit and normal irrigation conditions, except root/shoot ratio under both conditions and root length for testers under water deficit condition which were insignificant, indicating the importance of additive and non-additive genetic variances in determining the inheritance of these studied traits.…”

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“…There are 34 million ha of rainfed rice fields and 8 million ha of upland rice fields troubled by drought stress [19]. This abiotic stress can occur during rice development [20], for instance, in seedlings, where it causes improper growth and decreased yield [21]. Some investigations found that drought stress negatively affected the germination phase, seed vigor, photosynthesis activity, leaf membrane stability and osmotic content [22,23].…”