Genetic analysis through different generation means for grain yield and attributing traits in bread wheat (Triticum aestivum L.)

Abstract

Wheat is the second most important crop after rice in India. Information on nature and magnitude of gene action controlling grain yield and its attributing traits is prerequisites for selection of parents. An experiment was conducted in randomized block design with two replications under timely and late sowing environments at Gwalior during Rabi season of 2013 -14 and 2014-15. The six generations (P1, P2, F1, F2, BC1 and BC2) of bread wheat in three crosses viz., ‘HPW -296 X LOK -1’; ‘HPW - 296 X SONALIKA’ and ‘HPW - 296 X HW - 5205’ were evaluated for gene effects. The scaling test revealed the presence of non-allelic gene interaction for most of the characters, thereby, signifying inadequacy of additive-dominance model to interpret the gene effects. Gene action analysis revealed significant magnitudes of both additive and dominance gene effects for most of the traits. Both additive and additive X additive effects were significantly contributed in the expression of grain yield, grain filling period, days to physiological maturity, flag leaf area, and harvest index. The magnitudes of additive gene effects were relatively lower to corresponding dominance effects in most cases. Further both dominance and dominance x dominance effects were highly significant for plant height, days to physiological maturity, leaf canopy temperature, harvest index, biological yield and grain yield in all crosses. Whereas, only dominance x dominance effects were highly significant for spikes per plant, grains per spike, days to flowering, flag leaf area, seed index and in all crosses, thereby, showing importance of non- fixable components. Most of the traits were under the control of duplicate type of epistasis gene action. Heterosis over better and mid-parent in F1 generation and inbreeding depression in F2 generation showed significant for most of the characters also confirmed that these traits are highly under the control of non- fixable genetic components. Both additive as well as non additive effects were controlled expression of grain yield and some important attributing characters. Thus improvement of the characters needs intensive selection through later generation for fixing both additive as well as non additive gene action.