Genetic analysis of grain yield and its contributing traits in four bread wheat (Triticum aestivum L.) crosses using six parameter model

In order to create a successful and efcient breeding programme, it is highly helpful to analyse the gene action governing the expression of diferent traits. The objective of the present study was to use generation mean analysis to ascertain the kind and extent of gene action in bread wheat utilizing six generations (P₁, P₂, F₁, F₂, BC₁ and BC₂) of the four crosses, cross I (HD 2967 × PBW 752), cross II (RSP 561 × PBW 779), cross III (RSP 561 × PBW 780), and cross IV (JAUW 584 × WH 1184). These crosses included elite stripe rust resistant wheat genotypes in addition to locally adapted cultivars. The results showed that all the traits in all crosses had highly signifcant estimated mean efects (m), showing the quantitative inheritance of the selected traits. For grain yield and most of the selected characters, it was found that additive gene efects was shown to be less signifcance than dominance type gene efects. Among the diferent characters studied in the four crosses, the degree of dominance × dominance was large and negatively signifcant, whereas additive × additive gene actions were high and positively signifcance. In wheat breeding, it was found that selection for the improvement of grain yield and its contributing traits must be postponed until later generations because additive × dominant gene efects was of lesser signifcance.