Assessing Stability and Correlations Among Cotton Seed Quality Traits Across Multiple Environments Using the Stability Index

The stability of seed quality traits is a key factor for developing reliable cotton cultivars with consistent performance across diverse environments. This study evaluated six seed traits (1000-seed weight, crude protein, oil, ash, crude fiber, and moisture) across five commercial upland cotton cultivars grown in four distinct environments in Greece. Field trials were conducted in ten independent commercial fields per cultivar within each environment, with four samples collected from each field. Seed quality traits were analyzed using recommended official methods, and the Stability Index (SI) was calculated for each trait to quantify consistency across environments and cultivars. Traits such as 1000-seed weight, oil, and crude protein exhibited more consistent expression across environments and cultivars, whereas crude fiber and moisture showed substantial variation in stability across environments and cultivar × environment combinations, reflecting strong genotype × environment effects. Evaluation of relationships between traits revealed significant positive associations between 1000-seed weight and oil, and between crude protein and ash, as well as negative associations between 1000-seed weight and moisture and between crude protein and oil, indicating potential trade-offs among seed traits. Principal component analysis further highlighted trait associations and variability patterns across genotypes and environments. Overall, the combined use of Stability Index assessments and multivariate analyses provides a robust descriptive framework for evaluating cultivar performance and supporting cultivar selection under diverse agro-ecological conditions.