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

Abstract

In order to create a successful and efficient breeding programme, it is highly helpful to analyse the gene action governing the expression of different 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 x PBW 752), cross II (RSP 561 x PBW 779), cross III (RSP 561 x PBW 780), and cross IV (JAUW 584 x 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 significant estimated mean effects (m), showing the quantitative inheritance of the selected traits. For grain yield and most of the selected characters, it was found that additive gene effects was shown to be less significance than dominance type gene effects. Among the different characters studied in the four crosses, the degree of dominance x dominance was large and negatively significant, whereas additive x additive gene actions were high and positively significance. 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 x dominant gene effects was of lesser significance. Keywords:  wheat; grain yield; additive; dominance; epistatic gene effects