Genetic Studies on Agro-Morphological Traits in Rice (Oryza sativa L.) under Water Stress Conditions

The present investigation was carried out at the farm of Rice Research and Training Center (RRTC), Sakha, Kafr El-Sheikh, Egypt during 2014, 2015 and 2016 seasons. The evaluation were done based on estimation of heterosis, gene action, heritability, genetic advance and phenotypic correlation coefficient, some root and grain quality traits in rice using six populations technique, viz., P1, P2, F1, BC1, BC2 and F2 generation of three rice crosses namely Sakha 105 x WAB 450-T-B-P 3811-B (cross I); Sakha 104 x IR 66946-3R-178-1-1 (cross II) and Sakha 106 x Sakha 178 (cross III) were raised in a randomized complete block design. Flashing water irrigation was added after 10 days intervals. The current study aimed to determine the heterosis, gene action, heritability, genetic advance and phenotypic correlation response to selection and prediction by the new lines for the traits of days to 50 % heading, plant height, panicle length, number of panicles / plant, number of filled grains/ panicle, 100- grain weight, sterility % and grain yield/ plant. The results obtained from the mean of parents, F1 and F2 generations showed wide range in mean values between the parents and the presence of partial and over-dominance were found for all studied characters. Significant and highly significant positive estimates as a deviation from mid and better parents in all crosses for panicle length, number of panicles/plant and grain yield/plant, also highly significant positive estimates as a deviation from mid and better parents in the first two crosses for plant height. Scaling test provide evidence of non-allelic interaction in controlling all the characters studied in most crosses, the additive gene effect (d) was more important in the genetic system for all studied characters, dominance gene effects (h) and additive x additive gene effects (i) were played an important role in the inheritance of plant height, panicle length, number of filled grains/panicle, 100-grain weight, sterility percentage and grain yield/ plant. The additive x dominance (j) were significant and involved in the inheritance of days to 50% heading, plant height, number of panicles/plant, number of filled grains/panicle, 100-grain weight, sterility percentage and grain yield/plant. However, the dominance x dominance (l) were involved in the genetic control of all characters. Heritability estimates in broad sense were high. Meanwhile, heritability estimates in narrow sense were mostly low. The maximum genetic advance of the mean values was found to be high for number of panicles/plant, plant height and days to 50% heading characters. Highly significant and positive correlation was found for grain yield/plant with panicle length, number of panicles/plant, number of filled grains/panicle and 100-grain weight in all studied crosses. From the foregoing results, Sakha 105 x WAB 450-T-B-P 3811-B (cross I) and Sakha 104 x IR 66946-3R-178-1-1(cross II) could be recommended for growing under water deficit condition to achieve the highest rice grain yield and the highest values of saving water at the same time.