Components of Genetic Variances, Heritability and Genetic Advance in Maize Lines for Resistance to Northern Corn Leaf Blight in North-west Himalayas

The study on components of variances, genetic advance and heritability of northern corn leaf blight (turcicum leaf blight) was conducted at VPKAS, Almora during 1999–2001. Four susceptible (CM 128, V 327, V 128 and V 17) and two resistant inbred lines (V 335 and V 13) and their 15 F₁s, 15 F₂s, 15 BC₁s and 15 BC₂s, were generated for study of components of variances, genetic advance and heritability. Additive genetic variance (D), dominance (H) and environmental variance (E) were more in environment E₁ than in environment E₂ in most of the crosses which showed the importance of additive as well as non-additive components and also environmental variance. The broad and narrow sense heritability varied from cross to cross. However, their magnitude was higher in E₁ than E₂. The higher magnitudes of heritability estimates in E₁ were encouraging as it offered viable scope for selection in this environment. The estimates also revealed greater scope of genetic advance in E₁, nevertheless, high genetic advance expressed as percentage of mean were evident for turcicum leaf blight in both environments. The results showed that all types of gene effects viz., additive, dominance and epistasis were operating in the crosses in controlling resistance to turcicum leaf blight.