Evaluation of genetic parameters and heritability of traits in rice (Oryza sativa L.) using diallel method

To study the genetic control of grain yield and its components in rice using Hayman graphical method, 56 progenies obtained from diallel mating with eight parents (64 genotypes in total) were evaluated using randomized complete block design with three replications at research field of the Rice Research Institute of Iran in 2013. Agronomic traits, grain yield and its components were measured and recorded. Estimation of genetic parameters for grain yield by Hayman’s method showed that the additive variance (D) was less than the two components of dominance variance (H1) and (H2), and the average degree of dominance of genes is greater than one (1.741). Results showed that grain yield, filled grain number per panicle, 100-grain weight, panicle number per plant, and plant height were under the control of additive and non-additive effects as well as maternal and non-maternal effects. Line RI184421 (Sepidrood × Hasansaraei) and line 23 (IR75479-199-3-3) had the highest number of dominant and recessive alleles for grain yield, respectively. Plant height and panicle length was affected by the incomplete dominance effect, and grain yield, filled grain number per panicle, 100-grain weight and panicle number per plant were controlled by the overdominance effect. The broad-sense heritability of studied traits was high (˃ 90%). Narrow-sense heritability was high for plant height, indicating the importance of additive effects in the genetic control of this trait. Based on the results of this study, it is recommended that to improve grain yield and its components in rice that are controlled by the non-additive gene effects by using hybrid technology and to improve traits such as plant height and panicle length using selection based breeding methods due to the key role of additive effects in their genetic control.