Abstract
Combining ability studies were carried out for plant height, yield and yield components such as tillers per plants spike length, spikelets per spike and 1000-kernel weight, in a 7 x 7 complete dialleI cross of spring wheat varieties using Grillingss rnethod I and model 1. Mean squares for general and specific combining ability were highly siignificant fot all the characters under investigation. Significant reciprocal effects were also found for plant heigi:a, tillers per plant and spike length. The parents C 273, Va. 711 and LLT 26 showed high general combining ability for yield and most of its components under observation. The ranking of the best cross combinations for yield per plant on the basis of per se performance was almost similar to that placed upon SCA effects. The best crosses, in general, involved high a high and high x low general combiners. Additive gene action was found to predorni. nate all the characters except tillers per plant which showed non-additive type of gene action. Selection of the best combinations was suggested to be based on both per se performance and SCA effects,
INTRODUCTION
Reoorit breeding programmes which aim towards the evolution of new cultivars mostly depend upon blending different gcrimplasms from local and introduced varieties in such a way as would be advantageous in securing high yielding and widely adapted types. For the last couple or years it has been kit that the breeding programmes involving hybridization should be built on the basic knowledge of genetic make up and the nature of gene action.
