Multi-year evaluation of planting date and cultivar effects on cotton yield, fiber quality, and their temporal stability in a cotton–wheat double-cropping system in the Yellow River Valley of China

Optimizing planting date and cultivar choice is essential for balancing lint yield, fiber quality, and production stability in wheat-cotton double-cropping systems. However, their combined effects on yield-quality trade-offs and temporal stability (defined as the temporal mean divided by the temporal standard deviation) remain insufficiently quantified. A five-year field experiment (2019–2023) was conducted in the Yellow River Valley to evaluate four planting dates (PD1-PD4; May 10-June 10) and two contrasting short-season cotton cultivars (high-quality JK707; high-lint yield LM2387) with respect to lint yield, fiber quality, temporal stability, and trait trade-offs. Lint yield was significantly affected by both planting date and cultivar, peaking under the earliest planting (1229 kg ha −1 at PD1) and declined by 34.4 % under the latest planting (PD4). Fiber quality was predominantly genotype-driven, with cultivar significantly affecting all traits and planting date influencing only micronaire. JK707 achieved substantially higher Q-scores than LM2387 (66.84 vs. 46.97). Temporal stability indices revealed contrasting cultivar strategies: LM2387 showed high lint yield temporal stability under early planting (TS_LY=6.30 in PD1) but sharp declines under later dates (TS_LY=2.29 in PD4), whereas JK707 maintained relatively consistent lint-yield temporal stability across planting dates (TS_LY = 2.11–3.16) and greater stability in fiber quality traits. Yield-quality trade-offs were stronger in LM2387 (index 0.713 vs. 0.208) and were weakened by delayed planting due to concurrent reductions in yield and quality. A TOPSIS multi-criteria evaluation integrating lint yield, Q-score, and their temporal stability identified JK707 sown in PD2 as the optimal combination (Cᵢ = 0.57), followed by LM2387 in PD1 (Cᵢ = 0.531), whereas PD4 consistently produced the poorest performance. Aligning planting time with cultivar traits thus enhances production robustness and reduces climate-related risk, offering practical guidance for sustainable and climate-resilient intensification of wheat–cotton double-cropping systems and potentially benefiting similar systems worldwide. • Yield–quality trade-offs were stronger in LM2387, and delayed sowing weakened the trade-off but reduced yield. • Later sowing lowered micronaire and improved fiber length but caused major yield losses. • TOPSIS identified JK707 at normal sowing as the optimal yield–quality–stability combination.