Study of the gene action in controlling agronomic traits in maize (Zea mays L.) -using diallel crossing design

Study of the action of genes involved in controlling grain yield, plant height, ear height, ear length, ear diameter, grain/ear row, row no./ear, grain no./ear, 100 grain weight, cob percent, grain weight/ear, in maize, a diallel cross with 14 inbred lines was carried out. Parents and their F1's were tested using randomized complete block (RCB) design with three replications in Research station of Seed and Plant Improvement Institute, Karaj in 2006 cropping season. Significant (p<0.01) differences were observed among genotypes for all traits, therefore Griffing’s method 2, model 1 was used for subsequent diallel analysis. Variances due to general combining ability (GCA) and specific combining ability (SCA) were significant (P < 0.01), for all traits. Results indicated that for ear diameter, number of grain row per ear, 100 grain weight and additive gene effects were more important than non additive gene effects, but for grain yield, plant height, ear height, number of grain per row and number of grain per ear, non-additive gene effects were more important. For ear length, cob percent and grain weight per ear, both additive and non additive gene effects were important. High broad sense heritability observed for all traits (>60%), the estimate of narrow sense heritability for yield was 25%, high value belonged to the number of grain row per ear (71%) and low value obtained for ear height (18%). Parents with high GCA for grain yield were K19/1, K166B and K3615/2 inbred lines. For other traits, GCA effect was significant in about 50% of the inbred lines. SCA effect was significant in few crosses for all the traits. The highest heterosis for grain yield was observed in A679 × K3493/1 cross.