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Study on Heritance of Resistance to Common Smut in Maize

In order to study the genetic control of common smut in maize, eight inbred lines (two resistant, K1264/1 and K47/2-2-1-21-2, two moderately-resistant K74/1 and K47/2-2-1-4-1, two susceptible K19/1 and K19, and two very susceptibles K3304/1-2 and K47/2-2-1-3-3-1-1, were crossed in diallel in 2005 and evaluated in 2006 under artificial inoculation. All diallel crosses and parents were inoculated with a suspension of 106 sporidia per ml, 7-10 days after silking using tip injection method. At physiological maturity, disease severity was evaluated in each ear. Diallel analysis revealed the role of genes with additive and non-additive effects in genetic control of resistance. Lines K1264/1 and K74/1 with the highest negative GCA, had the least disease severity, while, K3304/1-2 with the highest positive GCA, had the highest infection. Cytoplasmic effect was also revealed for heritance of resistance to common smut. Ressesive alleles revealed to act as increasing and dominant alleles as decreasing factors of the disease severity. Wr/Vr graph showed K47/2-2-1-3-3-1-1 as holding the highest number of ressecive alleles, while, K1264/1 and K74/1 holding the highest dominant alleles..