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.