Abstract
A 5 x 5 complete diallel cross of wheat was analysed for combining ability of traits like plant height, number of fertile tillers per plant, days to heading, days to maturity, grain weight per ear, 100-grain weight and grain yield per plant. General and specific combining ability variances were significant except for grain weight per ear. Specific combining ability variances were significant for plant height, days to heading as well as maturity and grain yield per plant. While reciprocal effects were also significant for plant height, days to heading, number of fen& tillers per plant, grain weight per ear and grain yield per plant. Additive gene effects controlled the expression of all the traits under study as is evident by greater mean squares for general combining ability.
INTRODUCTION
For any breeding programme aiming at hybridization, the knowledge of genetic system controlling quantitative characters and combining ability of parents are the pre-requisites. Combining ability analysis developed by Grilling (1956) helps the plant breeders in providing such information in early generations. The present study was conducted to assess the relative magnitudes of GCA and SCA of some wheat cultivars so as to accelerate wheat breeding efforts of this department.
The results of Ahmad et at. (1984) revealed that general and specific combining ability (GCA & SCA) effects in wheat were significant for plant height. Guseinova (1985) found that general combining ability variances in wheat were significant for productive tillers while general and specific combining ability mean squares differed non-significantly for grain weight per ear. Widmer and Lebsock k973) revealed significant general and specific combining
ability mean squares for days to maturity and grain yield per plant. Shen et al. (1982) found highly significant general and specific combining ability mean squares in days to heading. Bhullar es al. (1981) estimated highly significant general combining ability mean squares for 100-grain weight.
MATERIALS AND METHODS
The experimental material comprised five different litres varieties of bread wheat, namely Pb-85, LU-26, Pak-81, S-1018 and S-131, All the twenty crosses, derived from these varieties by crossing in a dialtel fashion, were planted along with their parents in a triplicated randomized complete block design during 1986-87. Each replication had one row of 5 meter long for each treatment while plant to plant and row to row distance was 15 cm and 30 cm, respectively. Other cultural and agronomic treatments were kept constant for the whole experiment
