Multi-Environment Testing Based G x E Interactions Reveal Stable Host-Plant Resistance against Sterility Mosaic Disease in Pigeonpea

Sterility mosaic disease (SMD) is a serious biotic restraint in pigeonpea-growing regions of the Indian subcontinent. Disease control using chemicals like acaricides is not economical or sustainable, pointing towards host plant resistance as the ideal strategy for its management. In this study, from preliminary screening of 75 pigeonpea germplasm accessions and breeding lines, 21 pigeonpea genotypes showing moderate resistance to SMD were selected and again assessed at two multi-environment locations during Kharif 2021/2022 and 2022/2023. Analysis of variance partitioned the variation between the main effects of genotype and genotype x environment (GGE). The results revealed a significant variation (p < 0.05) in the SMD incidence between the tested genotypes, environment, and their interactions. Genotype variance contributed the greatest effect (63.56%) to the total variation and it represents the maximum disease variation. Furthermore, a significant positive correlation was found for the levels of SMD incidence between the test environments. We observed that SMD incidence had a high negative correlation with the maximum temperature (r = -0.933), and positively correlated with the rainfall (r = 0.502). Analysis of principal components 1 and 2 of the GGE explained 95.33% of the total variation and identified 10 genotypes (G1, G3, G4, G8, G10, G12, G13, G15, G20, and G21) showing moderate resistance stability across the environments. As new sources of resistance to SMD, these genotypes should be incorporated in pigeonpea breeding trials for further release. This research broadens the area of phenotyping and identifies stable resistance sources that can be used in future SMD resistance breeding projects.