Soybean [Glycine max (L.) Merr.] is the leading Indian oilseed crop grown under rainfed conditions. Meticulous understanding of genotype × environment interaction patterns is essential to develop superior and widely adaptable soybean varieties. In the current study, 32 soybean genotypes were evaluated at eight locations for two consecutive years. Additive main effect and multiplicative interaction ANOVA revealed that only 41.6% of variance was explained by the first two interaction principal component axes (IPCAs), leaving 58.4% to the remaining 13 IPCs. The weighted average of absolute scores (WAASB) stability index, a best linear unbiased prediction–based mixed model that takes in to account all the IPCAs, has been used in stability analysis. SL1171 (WAASB score, 4.09) was found to be highly stable among the genotypes under study, with grain yield (2,050.87 kg ha−1) lower than the grand mean (2,082.50 kg ha−1). A superiority index that allows weighting between mean performance and stability (WAASBY) was used to select stable and high yielding genotypes. MACS 1620 (WAASBY score, 74.47) was found to be high yielding (2,476.05 kg ha−1) and widely adaptable. A simultaneous selection index (i.e., multi‐trait stability index [MTSI]) has been used for selecting early‐maturing and high‐yielding genotypes. DSb 33 was found to have the lowest MTSI (0.001) and can be used as a parent for breeding for early maturity and higher yield. The 100‐seed weight was found to be positively correlated with grain yield and can be used in direct selection for grain yield. Through genotypic cluster analysis, NRC 146 was found to be more divergent, with the highest mean 100 seed weight (16.39 g), and therefore can be used as a parent for breeding solely for grain yield.

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Breeding for higher yield and wider adaptability are major objectives of soybean crop improvement. In the present study, 68 advanced breeding lines along with seven best checks were evaluated for yield and attributing traits by following group balanced block design. Three blocks were constituted based on the maturity duration of the breeding lines. High genetic variability for the twelve quantitative traits was found within and across the three blocks. Several genotypes were found to outperform check varieties for yield and attributing traits. During the same crop season, one of the promising entries, NRC 128,was evaluated across seven locations for its wider adaptability and it has shown stable performance in Northern plain Zone with > 20% higher yield superiority over best check PS 1347. However, it produced 9.8% yield superiority over best check in Eastern Zone. Screening for waterlogging tolerance under artificial conditions revealed that NRC 128 was on par with the tolerant variety JS 97–52. Based on the yield superiority, wider adaptability and waterlogging tolerance, NRC 128 was released and notified by Central Varietal Release Committee (CVRC) of India, for its cultivation across Eastern and Northern Plain Zones of India.

Anthracnose caused by Colletotrichum truncatum is a major soybean disease in India. Genetic resistance is the viable option to combat yield losses due to this disease. In the current study, 19 soybean genotypes were evaluated for anthracnose disease resistance at five locations (Medziphema, Palampur, Dharwad, Jabalpur and Indore) for three consecutive years (2017–2019) to identify stable and superior genotypes as resistant sources and to elucidate genotype (G) × environment (E) interactions. Genotype effect, environment effect and G × E interactions were found significant (P < 0.001) where G × E interactions contributed highest (42.44) to the total variation followed by environment (29.71) and genotype (18.84). Through Weighted Average of Absolute Scores (WAASB) stability analysis, PS 1611 (WAASB score = 0.33) was found to be most stable and through WAASBY superiority analysis NRC 128 (WAASBY score = 94.31) and PS 1611 (WAASBY score = 89.43) were found to be superior for mean performance and stability. These two genotypes could be candidate parents for breeding for durable and stable anthracnose resistance. Through principal component analysis, disease score was found to be positively associated with relative humidity, wind speed at 2 m above ground level, effect of temperature on radiation use efficiency and global solar radiation based on latitude and Julian day. Among the five locations, Indore was found to be highly discriminative with the highest mean disease incidence and could differentiate anthracnose-resistant and susceptible genotypes effectively, therefore can be considered an ideal location for breeding for field resistance against anthracnose disease.

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