Abstract

                                A 10 x 10 diallel analysis was made to assess the combining ability for yield and yield contributing characters involving divergent varieties of American cotton (Gossypium hirsutum L.) at Regl. Agrl. Research Station, Lam in four environments. The pooled analysis of variance revealed that GCA x E (except for monopodia per plant and sympodia per plant) and SCA x E (except for number of monopodia per plant) was important for all the characters. Though the magnitude of gca variance was considerably higher than the sca variance, both additive and non additive genetic variances were important for number of bolls per plant, boll weight and seed cotton yield per plant. Non additive genetic variance was found important for days to 50% flowering, number of monopodia per plant, number of sympodia per plant and number of seeds per boll. The parents NA 1325, NDLH 1678 and CWROK 165 were the best general combiners for number of sympodia per plant, number of bolls per plant, boll weight and seed cotton yield per plant. NA 1325 and NDLH 1678 also exhibited good general combining ability for days to 50% flowering in desired direction. The crosses NDLH 1678 x CWROK 165, L 604 X NDLH 1678 and MCU 5 x NA 1325 were identified as the best crosses on the basis of per se performance and combining ability.

Key words : Combining ability, Cotton, Additive, Non-additive.