Multi-environmental and multi-trait evaluation of elite finger millet genotypes for blast resistance using GGE biplot and stability analysis

Finger millet blast caused by Magnaporthe grisea poses a major threat, particularly in high-rainfall agroecological zones of India. Identifying stable and broad-spectrum resistance is crucial for sustaining productivity and ensuring food security. In the present study, a diverse panel of 58 finger millet genotypes was evaluated against finger millet blast across six distinct blast hotspot regions during the Kharif 2022–2023. Field evaluations under artificial inoculation revealed significant genotypic variability for blast severity across locations, with Mandya and Vizianagaram exhibiting the highest leaf blast severity. None of the genotypes found immune, however, 19 (32.76 %) showed resistant (R) and 35 (60.34 %) moderately resistant (MR) reactions. Genotypes such as GE4837, GE1559, GE4796, GE5812, GE1026 and VL149 consistently exhibited low disease severity across all blast stages and locations. Stability analyses using AMMI, Eberhart and Russell's regression model, CV% and AMMI stability value (ASV) identified GE5812, GE1559, GE1026 and GE4796 as the most stable and resistant entries. GGE biplot analysis further confirmed their stable performance and delineated two mega-environments, with Bangalore emerging as the most representative and discriminative site for resistance screening. Genetic variability analysis revealed high heritability and genetic advance for grain yield, fodder yield and blast traits indicating predominance of additive gene action and amenability to selection. Cluster analysis grouped genotypes into five clusters with the most resistant and stable entries aligning with GGE and AMMI findings. MGIDI analysis identified genotypes with lowest MGIDI index that were closest to ideotype across multiple traits. The findings of current investigation provide critical insights into the genetic architecture of blast resistance and its interaction with agronomic traits. The identified stable and resistant genotypes serve as promising donors for resistance breeding and pre-breeding and lays a strong foundation for breeding high-yielding, blast-resistant finger millet cultivars adapted to diverse agroclimatic regions.