Rapid screening for resistance of maize inbred and hybrid lines against southern corn leaf blight

Bipolaris is one of the most important phytopathogenic fungal genera to cause disease in cereal crops. Southern corn leaf blight (SCLB) is a pandemic and widespread disease; it's found everywhere corn is grown, causing a noticeable reduction in crop yield. Most cultivated varieties of maize do not resist SCLB disease where it is reported. Nevertheless, previous researchers have reported some resistant varieties of maize. In this study, we tested inbred and hybrid lines collected from ICAR-IIMR based in Ludhiana against the disease. The field experiment was setup using a Randomized Block Design with three replications in natural conditions. Here we evaluated lines by quantifying disease pressure, yield, and their attributes. Moreover, model-based clustering allowed the identification of five groups. For the SCLB disease confirmation, infected maize leaves were collected and used for pathogen isolation, and a pure culture was maintained. Both disease assessment and data analysis focused more specifically on characters that showed significant differences between means, especially leaf area, percentage of leaf infection, disease incidence, disease severity, disease index by plot basis, number of grain rows formed per ear, weight of maize kernels per ear, each corn ear weight, shelling percentage, and grain yield. The two best clusters identified, namely Group 1 and Group 2, together comprise 11002, 11009, 11026, 11030, 11069, 11149, 11153, 11185, 11328, 11333, 11337, 11347, 11370, 11385, 11074, 11351, 11356, 11357, 11608, and Karav-8523 lines. As per disease reaction, CM-500 is individually one of the best lines in terms of SCLB resistance. Specific symptoms were clearly found on leaves, and pseudo-septate conidia were observed under the microscope. Thus, several lines exhibited highly resistant reactions against SCLB, especially 11002, 11009, 11026, 11069, 11074, 11337, 11347, 11385, and CM-500, and can still be recommended for farmers and in breeding programmes, for future usefulness as industries are complaining of maize shortages, and they present a great commercial potential.