Heritability of and correlations among genotype-by-environment stability statistics for grain yield in bread wheat

Several genotype-by-environment stability measures are in use, but little i nformation exists about their inheritance or genetic inter-relationships. A mong those measures in common use are the linear regression coefficient (b) , deviations from regression (S-b), coefficient of determination (R-2), coe fficient of phenotypic variation (CPV) and, more recently, interaction prin cipal components (IPCA) of the additive-main-effect-and multiplicative-inte raction (AMMI) model. Because of the factorial structure of the data, the d iallel cross is well suited to study these parameters and their relationshi p to quantitative traits. For this study a complete diallel cross, derived by mating eight lines from a broad based bread wheat breeding population, w as grown for several growing seasons at two Ugandan locations, one of which was prone to yellow rust. Stability parameters and grain yield were measur ed for each cross. CPV had the highest narrow-sense heritability (h(2)=0.52 2) followed by IPCA1 of the AMMI (h(2)=0.461). Lowest narrow-sense heritabi lities were calculated for b and R-2 (h(2)=0.150 and 0.100 respectively). T here were high additive genetic correlations (r(A)) between grain yield and CPV (r(A)=-0.933), grain yield and IPCA1 (r(A)=0.707), and grain yield and IPCA2 (r(A)=0.751). The genetic association between CPV and IPCA1 was also high and negative (r(A)= -0.934). These results suggest that it may be pos sible to select simultaneously for high and stable grain yield in this broa d-based bread wheat breeding pool by selecting outyielders that exhibit a l ow CPV.