Phenotypic Diversity Analysis and Screening for Northern Corn Leaf Blight Resistance in Maize (Zea mays L.) Landraces Grown in North Eastern Hill Region of India

A total of 139 diverse maize landraces from seven hill states of North East India were evaluated for genetic diversity and resistance to Northern Corn Leaf Blight (NCLB) in an augmented design. ANOVA for cob and flowering characteristics were highly significant. PCA revealed cob traits contributed to PC 1 while flowering traits loaded on PC 2. Agglomerative Hierarchical Clustering (Ward's method) grouped the landraces into four distinct classes on cob weight variation. For NCLB resistance, qualitative disease assessment under natural field conditions followed by controlled quantitative assessment based on AUDPC scores were consistent for the landraces studied implying genetic basis of inheritance. SSR markers which map close to resistant Ht genes when run on a subset of the landraces showed distinct polymorphism specifically between the most susceptible T(9)8) and resistant landrace M9(4) collected from Tripura and Meghalaya, respectively for markers close to resistant Ht2 gene. Diversity and disease screening studies hereby establish presence of genetic variability for initiating or fortifying resistance breeding programmes.