Genetic analysis of yield and yield components in Oryza sativa x Oryza sativa cross
The number one goal of most rice improvement programmes around the world is breeding for high potential to take care of the increasing consumption of rice. The objective of this experiment was to study the inheritance of yield and yield components and to estimate the heritabilities of important quantitative traits in rice (Oryza sativa L.). Six generations viz., P1, P2, F1, F2, BCP1 and BCP2 of a cross between IET6279 and IR70445-146-3-3 were used for the study. Generation mean analysis suggested that additive effects had a major role for the expression of plant height, number of panicles, number of spikelets per panicle, percentage spikelets fertility per plant and grain yield per plant, which further suggested that phenotypic selection was possible at an early stage. Both additive and non-additive gene actions were important for the expression of number of fertile spikelets per panicle and 100-grain weight. Therefore, selection for these characters would be fruitful, if delayed till epistasis effects are reduced to a minimum. High broad sense heritability estimates were observed for characters viz. plant height and 100-grain weight, suggesting that the characters under study are less influenced by environment in their expression. Thus, selection based on phenotypic value of these characters would be reliable and effective. Low estimates of broad sense heritability were observed for number of panicles per plant, number of spikelets per panicle, number of fertile spikelets per panicle, percentage spikelets fertility per plant and grain yield per plant, indicating that influence of the environment was high for these characters. Therefore, superior genotypes selection based on phenotypic performance for these characters may not effective.
Key Words: Additive, gene action, heritability, inheritance, non- additive, rice