Genetic analysis of resistance to Turcicum Leaf Blight in semi-temperate early maturing genotypes of maize (Zea mays)

摘要

Turcicum leaf blight (Exserohilum turcicum) is the most common and chronic disease of maize, especially in Himalayan hilly region. Studies on inheritance of the disease were conducted using six generations derived from 4 susceptible (CM 128, V 327, V 128 and V 17) and 2 resistant inbred lines (V 335 and V 13) having early maturity suited to hilly region. The 6 parents and their 15 F-1's, 15 F-2's, 15 BC1's and 15 BC2's, were studied for reaction to turcicum leaf blight at 2 locations namely, Hawalbagh Research Farm of Vivekananda Parvatiya Krishi Anusandhan Sansthan, Almora during kharif 2000 and at Sihora Farm, Rudrapur during rabi, 2000-01. Significant additive and dominance variances were observed in most of the crosses in the two environments mentioned above. The study suggested that both additive and dominance components were important in the inheritance of turcicum leaf blight, the magnitude of additive component being relatively higher than non-additive component. Gene interactions and environment were also found to be important. The resistant lines V 335 and V 13 were found to be the best general combiners. Highly significant SCA effects were observed in both environments in 3 crosses, viz. V 327 x V 335, V 335 x V 17 and V 13 x V 128, which involved one disease resistant parent. Significant GCA and SCA variance also indicated that the additive and nonadditive components were important in the inheritance of resistance to turcicum leaf blight in maize. Low to high H-ns estimates were observed with good genetic advance, especially at Hawalbagh during kharif 2000. The higher estimates of additive component of variance, heritability and genetic advance during kharif 2000 indicated that selection for turcicum leaf blight resistance was likely to be more effective at Hawalbagh during kharif than at Rudrapur during rabi. Population improvement approach, preferably, reciprocal recurrent selection may be followed for the development of early maturing and turcicum leaf blight resistant cultivars of maize, especially for the Himalayan hilly region.