Fiber Quality and Stability of Partially Interspecific Cotton Lines Under Irrigation and Nitrogen Environments

Cotton is one of the most important crops worldwide, having considerable economic importance in Greece. This study aimed to evaluate the fiber quality traits of partially interspecific cotton lines under contrasting irrigation and nitrogen environments within a strip-split block field design. Experiments conducted over two consecutive years include a control (commercial cultivar Celia) and four partially interspecific lines of the Pa7 generation (Gossypium hirsutum × G. barbadense). Three irrigation and two nitrogen fertilization levels were applied. Significant differences were observed among genotypes and environments for all fiber quality traits, with some year-to-year variation. Genotypic response for yellowness was influenced by fertilization. Across the two experimental years, a strong Fertilization × Environment interaction was observed, and in the second year, a Genotype × Fertilization × Environment interaction was detected for the uniformity index. Pa7 lines consistently outperformed Celia in fiber length (≈33 vs. 30 mm) and elongation (≈7.0 vs. 5.5%), while exhibiting higher yellowness values. Fiber strength, micronaire, uniformity, and reflectance varied between years but remained within acceptable ranges. Overall, Pa7 lines demonstrated superior fiber quality and stability under variable conditions, highlighting their potential for breeding programs. These findings support the importance of integrating interspecific germplasm with suitable irrigation–nitrogen management to improve cotton fiber performance and resilience under diverse cultivation environments.