Studies on generation mean analysis in rice (Oryza sativa L.)

Abstract

Genetic analysis using generation mean analysis is a tool for designing the most appropriate breeding approaches for developing rice varieties. An attempt was made with seeds of five generations viz., P1, P2, F1, F2 and F3 for each of four cross combinations IR 75000-69-2-1-B x ADT 45, IR 75000-69-2-1-B x ADT 36, IR 63311-B-3R-B-2-4-3 x ADT 45 and IR 63311-B-3R-B-2-4-3 x ADT 36 were constituted and raised in RBD design with three replications. Observations were recorded for days to first flower, plant height, total number of tillers per plant, number of productive tillers per plant, panicle length, number of grains per panicle, grain weight per panicle, thousand grain weight and grain yield per plant. The results revealed the presence of additive, dominance and two types of interactions along with complementary and duplicate interaction were found to govern yield and all its component traits. For improvement of grain yield and its components additive, dominance and epistatic interactions viz., additive x additive and dominance x dominance along with complementary and duplicate type of gene actions were important. Thus, predominance of unfixable and non-additive gene action was observed for all the traits, hence it appeared to be difficult to adopt pedigree breeding as simple pedigree breeding will not be able to fix the superior lines in the early segregating generations. Hence, selection should be postponed to later generations or one or two cycles of reciprocal recurrent selection may be followed by pedigree breeding for improvement of the economic traits.