Evaluation of maize (Zea mays L.) germplasm for resistance to maydis leaf blight disease

Fungus Cochliobolus heterostrophus (Drech.) known as maydis leaf blight (MLB) or southern corn leaf blight, causes significant damage to maize crops and substantially reduces grain production. It is prevalent in warm and humid maize-growing areas throughout the world. The present study was aimed at the identification of stable sources of resistance to MLB. A set of 82 diverse inbred lines of maize were evaluated under artificial epiphytotic conditions at MLB hotspot location Delhi for two years (2020 and 2021) and in the third year at three MLB hotspot locations, namely, Delhi, Ludhiana, and Karnal during kharif 2022. The incidence of MLB was meticulously scored using a 1-9 rating scale. Based on two years’ pooled data (2020 and 2021), eight genotypes, namely, IC0620945 (DML-1278), IC0620960 (DML-1390) (Score 1.95–2.85); IC0620992 (DML-1575) (Score 0.47–2.50), IC0620997 (DML-1634), IC0621026 (DML-1828), IC0621030 (DML-1834), IC0621040 (DML-1851) and IC0612726 (DML-212-1) were resistant to MLB with score ranging from 0.47 to 3.00. These eight lines were further subjected to multi-location evaluations, Ludhiana, Karnal, and Delhi, for validation of MLB resistance. Only four lines, viz., IC0620960 (Score 1.4–2.4), IC0620992 (Score 2.0–2.5), IC0621026 (Score 1.1–2.0) and IC0621040 (2.0–2.8) could confirm resistance to MLB at all the three locations. Thus, the identified four resistant maize inbred lines may be utilized for developing promising maize hybrids with a high degree of resistance to the devastating MLB disease. Further studies can focus on understanding the genetic basis of resistance in these resistant sources and accelerate the variety development using marker-assisted breeding.