STUDY ON COMBINING ABILITY AND HETEROSIS IN TOMATO (Lycopersicon esculentum Mill)

Abstract

To asses the combining ability a genetically diverse seven parent diallel set (without reciprocal) of tomato (lycopersicon esculentum Mill.) was grown in order to reveal the nature and magnitude of various gene action involved and test the percent hcterosis in the expression of yield and its components. Both General Combining Ability (GCA) and Specific Combining Ability (SCA) were estimated for eleven morphological and reproductive characters. The variances due to GCA and SCA were highly significant for almost all the characters indicating the predominance of both additive and non-additive gene actions. The parent P3 appeared as the best general combiner for early flowering, fruits per cluster and fruits per plant, P7 for plant height at 50% flowering, fruits per cluster, fruits per plant, individual fruit weight, yield per plant and brix%, Pl for plant height at 50% flowering, plant height at last harvest, individual fruit weight, fruit breath, brix% and locules per plant and P2 for individual fruit weight, yield per plant, fruit length, fruit breath and locules per plant. The cross combinations P3xP6, Pl xP3 and P3xP7 were the superior for earliness as these showed significant negative SCA effects, P2xP6, P4xP7 and P6xP7 for fruits per cluster, P4xP7, P2xP7, P2xP6 and P3xP5 for fruits per plant, Pl xP7, PlxP2, P3xP7 and P3xP6 for individual fruit weight, P4xP7 and P2xP6 for yield per plant, Pl xP7 and P3xP6 for brix%. Considerable heterosis over the better parent was found in a number of characters in many hybrids. Highest significant positive heterobeltosis for fruits per cluster was observed in the cross P4xP6 (23.73%), for fruits per plant cross P4xP7 (83.88%), for individual fruit weight cross Pl xP7 (16.67%), for fruit yield per plant cross P4xP7 (62.3 I%) and for brix% highest heterosis was observed in the cross Pl xP7 (31.89%).