Epistasis Effects of Yield and some Morphological Traits in Maize by Triple Testcross

Choice of efficient breeding program depends on the knowledge of the genetic system controlling the character to be improved. To estimate the genetic parameters for yield, yield components and some other morphological traits in corn (Zea mays L.), B73×MO17 and B73×K74/1 crosses were studied by triple testcross method. The experiments were conducted at research field of Seed and Plant Improvement Institute (SPII) in 1999-2001. Significant differences were observed among means of F1 , P1 and P2 testcrosses for all of the traits in both crosses. The B73 testcrosses generally had greater means than MO17 and K74/1 testcrosses except for number of leaves in two crosses, cob weight in cross B73×MO17 and anthesis silking interval in cross B73×K74/1. B73 testcross seems to contribute significantly in the expression of positive epistatic effects. Epistasis effects were significant for all of the traits in both crosses. Partitioning of the epistasis effects into fixable and non-fixable components revealed that additive×additive effects (fixable) were not significant for the traits except for days to silking in both cross, anthesis silking interval and plant height in cross B73×MO17, but additive×dominance and dominance×dominance effects (non-fixable) were significant for all of the traits in both crosses.