Inheritance pattern of yield attributes in spring wheat at grain filling stage under different temperature regimes

Abstract

One hundred spring wheat accessions were assessed for heat tolerance under plastic sheet tunnel resulting in seven parents with diverse heat tolerance. Tolerant and susceptible genotypes were graded on the bases of their relative cell injury percentages and relative values for different yield components. The analysis of variance for relative cell injury % revealed highly significant differences among the genotypes with a range from 28 to 98 %. These 7 parents were crossed in a full diallel system to evaluate the inheritance pattern of some spike related yield attributes (spike length, spikelets per spike, spike density, spike weight, grains per spike and grain yield per plant) under different temperature regimes at grain filling stage. Preliminary ANOVA revealed significant genotypic variation (P<0.01) for all the traits studied under both environments. Spike length, spikelets per spike and spike density revealed partial fitness of data for additive dominance model under normal conditions while other traits like spike weight, grains per spike and grain yield per plant showed full adequacy. Under heat stress all traits showed partial adequacy except for grains per spike which showed full adequacy. Formal ANOVA displayed significant effects for both additive and dominance effects in most characters under both regimes. Grain yield per plant showed significancy for only 'a' item under normal conditions and both 'a' and 'b' under high temperature regime. The additive component of variance (D) was significant and more than dominance variance H1 and H2 for spike length, spike density and grain yield per plant under both temperature regimes showing preponderance of additive effects. Grains per spike showed prevalence of dominant gene action under both conditions. Spikelets per spike and spike weight showed dominance effects under normal conditions and additive ones under heat stress. Estimates of narrow sense heritability were moderate to high in almost all the traits except for spikelets per spike under normal conditions in which it was low. Predominance of additive genetic effects in majority of traits under heat stress suggested early generation selection through pedigree method while presence of non-additive effects may respond to heterosis breeding.

Publication Title

Australian Journal of Crop Science

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