Spectral indices as predictive tools for evaluating mungbean yellow mosaic virus resistance

Abstract

Mungbean is a protein-rich, nitrogen fixing pulse crop and nutritionally known as “Queen of pulses”.Its productivity is severely constrained by Mungbean yellow mosaic virus (MYMV). Reliable and rapid assessment of diseaseseverity is essential for resistance breeding as conventional visual scoring is often subjective and labour-intensive. Thisstudy evaluated the potential of non-destructive spectral tools, SPAD chlorophyll meter readings (SCMR) and the Normalized Difference Vegetation Index (NDVI) as indicators of MYMV resistance in twenty eight pre-screened mungbean genotypesunder field conditions at UAS, Dharwad (summer 2025). Results revealed that resistant genotypes (DGG 96 and IPM2-14) maintained significantly higher chlorophyll content (SCMR: 51.53,48.42 and 49.46, 45.96) and NDVI values(0.76, 0.73 and 0.75, 0.71) at 30 and 45 DAS whereas highly susceptible genotype DGGV 2 exhibited pronounced declines(SCMR: 30.77, 22.21; NDVI: 0.42, 0.33 at 30 and 45 DAS). Moderately resistant entries displayed intermediate physiologicalresponses. The findings confirmed that higher chlorophyll retention and canopy vigour are closely associated with resistanceto MYMV.Thus SCMR and NDVI provide reliable, rapid and non-invasive alternatives to visual scoring and their integrationinto breeding programs can accelerate the identification and development of durable MYMV-resistant mungbean cultivars.