Host response of elite maize inbreds and hybrids against maydis leaf blight under epiphytotic conditions

Maydis leaf blight (MLB) incited by ascomycetes fungus Bipolaris maydis is a serious foliar disease of maize under warm and humid conditions. The fungus has a wide host range and may cause significant yield losses by producing symptoms that appear as young, small and diamond-shaped lesions under favourable conditions. MLB can be managed by various means, but host resistance is most effective, environment friendly and practical approach to manage this disease. In order to find out new sources of genetic resistance, the present investigations were carried out at CCS HAU, Regional Research Station, Karnal, Haryana, India, to evaluate 104 inbreds and 35 hybrids during kharif 2019 and 2020 under artificial epiphytotic conditions. Data on disease severity were recorded using 1–9 disease rating scale, and screened genotypes were grouped into four categories, viz ., resistant, moderately resistant, moderately susceptible and susceptible based on disease reaction. A significant difference was observed in disease severity of the genotypes screened where 13 inbred lines, viz., HKI 193–2, HKI-323, HKI-295, HKI-488 T, HKI-1128, MBR-139, HKI-161, HKI-193–1, HKI-193–2, HKI-488-1RG, HKI-1025, HKI-1128, HKI-1344, were found resistant, 32 inbred lines exhibited moderately resistant reaction, 46 were found moderately susceptible, while 13 inbreds exhibited susceptible reaction against MLB. Amongst 35 hybrids screened eight hybrids, viz ., HQPM-1, HQPM-4, HKI1651 × HKI193-2, HKI 193–2 × L-287, HKI-1105 × IMR 307, HKI-295 × L-287, HKI 488 T × L-287, HKI 659–3 × L-287, were found to be resistant, 23 were observed moderately resistant, 3 were observed moderately susceptible, and one hybrid exhibited susceptible reaction against the disease. Two inbreds, viz., HKI-1128 and HKI-193–2, and one hybrid HQPM-1 were found resistant during both years of screening. The resistant genotypes may be further utilized in order to determine the nature of resistance or in breeding programmes to develop promising MLB-resistant hybrids.