Combining ability analysis over environments in bread wheat

Thirty-eight genotypes of wheat including 8 parents, their 28 F1s and 2 checks evaluated in 4 different environments i.e. early sown, normal sown, late sown and very late sown conditions was undertaken to study the combining ability in bread wheat for grain yield and its component traits. From pooled analysis, it was found that mean square due to GCA and SCA were significant for all characters which revealed difference between parents for GCA and difference between crosses for SCA. Significant mean square for GCA x E and SCA x E for proline content, chlorophyll content, chlorophyll stability index and heat injury was observed. In addition, SCA x E for grain yield was also significant. This suggested that additive and non-additive genetic components were sensitive to environments. Variance for GCA was higher than their respective SCA variance for grain yield per plant, leaf canopy temperature, proline content and chlorophyll stability index which suggested that additive component was less stable over the environment than dominant component. Parents HD 2987 was good general combiners for grain yield over different environments. Cross HI 1544 x HD 2987 was the best specific combiner for grain yield per plant followed by HI 1544 x RAJ 4079.