Assessing Resistance in Maize Genotypes to Banded Leaf and Sheath Blight (Rhizoctonia solani f. sp. sasakii) under Artificial Epiphytotic Condition

Maize (Zea mays L.), the second principal cereal crop in Nepal, faces severe yield constraints due to biotic stressors, notably banded leaf and sheath blight (BLSB), a fungal pathogen incited by Rhizoctonia solani f. sp. sasakii. This disease manifests devastating yield losses, quantified between 11% to potentially 100% failure under optimal environmental conditions. Host resistance constitutes a cornerstone of integrated disease management (IDM) strategies to ensure agricultural sustainability. In this study, 120 maize genotypes were subjected to artificial inoculation under controlled epiphytotic conditions at the National Maize Research Program (NMRP), Chitwan, to delineate genetic resources conferring resistance to BLSB. Inoculation was administered at the knee-high stage, followed by systematic evaluation of disease incidence percentage (PDI), percent disease severity (PDS), Area Under Disease Progress Curve (AUDPC) and grain yield. Twenty genotypes demonstrated superior resistance profiles, exhibiting mean PDI (40%), PDS (19%), and AUDPC (468), alongside a mean grain yield of 3.91 t/ha. Linear regression analysis elucidated that AUDPC accounted for 97% of the phenotypic variance in grain yield (R² = 0.97), underscoring a significant inverse correlation. These genotypes represent novel genetic reservoirs for introgression into elite cultivars, advancing the development of BLSB-resistant maize hybrids to mitigate yield losses in Nepal’s agroecosystems.