Combining ability analysis of grain yield and other component characters in durum wheat (Triticum durum desf.)

Forty five hybrids developed by diallel mating design excluding reciprocals along with ten parents were studied for the estimation of combining ability variances and its effects. The analysis of variance for combining ability revealed that mean square values due to parents were significant for all the characters except for grain yield per plant and kernel length. Likewise, mean square values due to hybrids were significant for all the characters except for length of main spike, spike density and kernel length which revealed that existence of differences among the parents and hybrids. Significance of both σ²_GCA and σ_SCA for the characters days to 50% heading, days to maturity, peduncle length, number of spikelets per main spike, number of grains per main spike, grain yield per main spike, protein content, sedimentation value and ? carotene suggested that importance of both additive and non-additive gene effects for the inheritance of these characters. The estimates of potence and predictability ratio revealed preponderance of additive genetic variance for the characters days to 50% heading, number of spikelets per main spike and number of grains per main spike. The value of average degree of dominance was close to unit and zero for the characters days to 50% heading and specific sedimentation volume which suggested existence of complete dominance and absence of dominance for these characters, respectively. The parent GW 1 was good general combiners for the characters days to 50% heading, days to maturity, length of main spike, protein content and sedimentation value. Whereas, the cross GDW 1255 x GW 2007-112 was good specific combiner for days to 50% heading, days to maturity, number of spikelets per main spike, number of grains per main spike, grain yield per main spike, test weight, harvest index and sedimentation value.