Evaluation of Morpho-Physiological Traits in Rice Genotypes for Adaptation under Irrigated and Water-Limited Environments

Drought is one of the major limitations to rice productivity worldwide. The present study compared variation in seventeen rice genotypes of Egyptian origin for morpho-physiological traits to identify the best genotypes with combination of adaptive traits under water-limited condition (DS). The DS reduced days to heading (DTH), plant height (PH), flag leaf angle (FLA), flag leaf area (FLAR), chlorophyll content (CHC), relative water content (RWC), grain yield (GY), and its components. Among genotypes, Hybrid 2 expressed the highest GY, panicle length (PL), number of tillers (NT), panicles per plant (NPP), and harvest index (HI) with maximum spikelet sterility (SS) under non-stress condition (NS), while the same genotype expressed ≈ 41% yield reduction under DS. The genotype Giza 179 had earlier DTH, higher and stable GY, FLAR, and yield component traits such as NPP, PW, and HI across the water regimes with least yield reduction (30.5%) under DS. The GY and FLAR, RWC, PL, NT, NPP, PW, and HI were positively correlated under DS. The cluster analysis showed a similarity index of 25% among genotypes. The high yielding genotypes Giza 179, IET 1444, and IRAT 170 had also increased yield components (PL, NT, NPP, PW, TGW and HI) under DS that were attributed to highest FLAR, RWC, and PH, while having reduced LR, FLA, TR, and SS; therefore, these genotypes were categorized as drought-tolerant. The Hybrid 2 and Giza 179 genotypes can perform well under NS; however, the cultivation of Giza 179, Sakha 107, IET 1444, and IRAT 170 would give an advantage in DS-prone areas, hence, these can be used as a donor parental line in future rice breeding programs