DIALLEL ANALYSIS FOR STUDYING HETEROSIS AND COMBINING ABILITY OF SOME ECONOMICAL YIELD TRAITS IN PUMPKIN
This study was conducted in research farm and laboratories of Horticultural Research Institute, Agric. Res. Center during the period from 2012 to 2014 to estimate heterosis, and both general and specific combining abilities of some pumpkin (Cucurbita maxima Duch. ex Poir. economical traits, viz. main stem length, number of branches/plant, number of nodes to first female flowers, average length, diameter and weight of fruit, average flesh thickness, number of fruits/plant, and total yield/plant. Five different inbred lines of pumpkin, namely PK 27A (P1) PK 27 (P2) PK 26 (P3) PK 33 (P4) and PK 31A (P5) were used for carrying out half diallel cross in all possible combinations excluding reciprocal. Results showed that the maximum significant true heterosis in desirable direction (71.8% was recorded for TY followed by NB (67% AFW (41.9% NF (40.5% MSL (39.5% NNF (29.1% AFL (28.7% and AFD (12.4% Analysis for combining ability indicated that general (GCA) and specific combining ability (SCA) variances were highly significant, indicating that both additive and non additive gene effects involved in the expression of all studied traits except for NB and NF traits which were mainly controlled by non additive and additive types of gene action, respectively. The ratios of GCA/SCA were higher than unity suggesting that the additive and additive by additive type of gene action was more important for most traits. Based on general combining ability effects, the parental lines P3, P4 and P5 were good combiners for most studied traits. The highest desirable SCA and heterotic effects were obtained from the crosses; (P1 x P4) (P2 x P3) and (P3 x P5) for yield and most of the studied traits, which are the best and promising hybrids.