Genetics of yield determining factors in spring wheat over environments

Genetics of yield determining factors was studied in a set of 10 X 10 half-diallel progenies (F1 and F2) of springwheat over three environments. The results of components of variance analysis pooled over environments revealed that both additive (D) and nonadditive (H1 and H2)components of variation were involved in the expression of almost all the characters in F1 as well as F2 generations. However, the nonadditive components were higher than additive component excegt in few cases in F1 where the additive component was preponderant. The {H1/D)1/2 values revealed overdominance for all the characters in both generations except for days to heading, plant height, peduncle length, spike length and spikelets per spike in F1, where partial dominance was recorded. The values of Fexhibited excess of dominant alleles for days to heading, days to maturity, spikelets per spike (F1 and F2) and peduncle length (F2), and directional dominance of the decreasing genes for plant height and spike length (F2. Biparentalmating and/ordiallel selective mating system could be the best breeding method for more tangible advancement in spring wheat.