Genetic analysis of resistance to common smut in maize (Zea mays L.) using triple test cross

Abstract

Understanding of gene action for resistance to maize common smut is essential for maize breeding programs, therefore, triple test cross analysis was employed to assess gene action controlling resistance to common smut in maize. Parental inbred lines and their progenies were evaluated using randomized complete block design with three replications in Karaj Field Station, Seed and Plant Improvement Institute, in 2007 and 2008 cropping seasons. Epistasis was observed for resistance to maize common smut. Partitioning of the total epistasis revealed that [i] type (additive × additive) and [I+J] types (additive × dominance and dominance × dominance) were highly significant. Additive (L1i+L2i) and dominance (L1i – L2i) effects for resistance to maize common smut were also significant, over two growing seasons. Dominance ratio (H/D) 1/2 indicated that resistance to maize common smut was controlled by dominance effect. However, the direction of dominance (rs,d) for this character in two growing seasons was not-significant which implies that dominant alleles were distributed in parents, therefore they did not express any directional dominance for this attribute. Since F′ was positive, therefore, dominant alleles increased disease severity of maize common smut. Cytoplasmic effects were also important for resistance to maize common smut. Combined analysis of variance showed that the effect of year and genotype × year interaction were highly significant. Generally, the additive, dominance and epistatic components were important in resistance to maize common smut. It is concluded that Genetic analysis of Resistance to Common Smut in Maize (Zea mays L.) using triple test cross recurrent selection procedure may be efficient in breeding for resistant to maize common smut, since it exploits additive and non-additive components of genetic variation for improvement resistance to maize common smut. Key words: Zea mays, triple test cross, common smut, gene action.