Evaluation of some Rice Genotypes (Oryza sativa L.) Under Normal and Heat Stress Conditions تقييم تراکيب وراثية مختلفه من الأرز تحت الظروف الطبيعية والإجهاد الحراري

Abstract

The aim of the current study was to evaluate 25 rice genotypes under normal at Sakha, Kafr El-Sheikh, Egypt and under heat stress conditions at New Valley, Egypt during two rice growing seasons of 2017 and 2018. Data were collected on eight traits i.e., flag leaf area, flag leaf angle, plant height, panicle length, panicles plant-1, 1000-grain weight, fertility percentage and grain yield plant-1. High amount of genetic variation was found among the studied genotypes under normal and heat stress conditions. All studied genotypes were negatively affected by high temperature. The most affected traits by heat stress were fertility percentage, grain yield plant-1, flag leaf area and panicles plant-1 with average reductions of 73.59, 64.22, 42.46 and 41.31%, respectively. Correlation and path coefficient analysis showed that number of panicles plant-1 and fertility percentage were good indicators for grain yield under heat stress condition. Based on the HSI values of grain yield plant-1 and fertility percentage, both genotypes N22 and Giza178 could be identified as heat tolerant (HSI value was ≤0.5 for both traits). Based on the results of PCA analysis, the most desirable genotypes under heat stress were Giza178, N22, Bala, Dular, WAB56-104, Sakha104 and Egyptian Yasmin. According to the current investigation, it could be concluded that those eight genotypes could be used in breeding programs as donors for developing high yielding heat tolerant promising lines. In addition, Egyptian rice varieties; Giza178, Sakha104 and Egyptian Yasmin are suitable for cultivating under both normal and heat stress conditions in Egypt.