Breeding values, stability, and heterotic grouping of Asian Saccharum spontaneum collection for parental selection in...

Sugarcane breeding is constrained by a narrow genetic base, limiting progress in ratooning ability, stress tolerance, and climate resilience. Although Saccharum spontaneum harbors valuable genetic diversity, its systematic utilization in breeding remains limited by a lack of multi-environment evaluations. Therefore, 100 Asian S. spontaneum clones were assessed across six environments (two locations × three crop cycles) during 2022-2025 using an integrated framework that combined BLUP breeding values, AMMI-based stability indices (ASV, GSI, HMRPGV, WAASB), and the multi-trait selection index MGIDI. Heritability, repeatability, and genetic correlations were estimated to support selection decisions. Moderate heritability was observed for stalk diameter and stalk height, while juice Brix and stalk weight showed low heritability. The clones were classified into four heterotic groups; only three clones (C059, C086, and C089) met both high-performance and high-stability thresholds, forming Group A (elite + stable). Group B (high performance, low stability) included 22 clones, Group C (low performance, high stability) included 22 clones, and Group D (moderate) comprised the remaining 53 clones. Repeatability from first to second ratoon was remarkably high (≥0.90) for most morphological traits, except stalk weight (0.07). Genetic correlations revealed a trade-off between juice Brix and internode length, and a positive association between tillering rate and fresh biomass. Crossing strategies should prioritize Group A × Group B and crosses between geographically distant origins (e.g., Yunnan × Hainan) to maximize heterosis. The three elite clones are recommended as immediate parents for climate-adaptive breeding programs.