Thresholds and moderating factors for cotton fiber quality under deficit irrigation: A global meta-analysis

Deficit irrigation has emerged a key strategy to mitigate water scarcity in arid and semi-arid regions. However, its impact on fiber quality remains inadequately understood. This meta-analysis provided a systematic quantitative assessment of how various external environmental factors affect cotton fiber quality under deficit irrigation. Results demonstrated that deficit irrigation generally compromised fiber quality, leading to shorter fiber length, reduced strength, and unstable Micronaire, but key environment and agronomic practices have been confirmed mitigate fiber quality loss, including cultivated in sandy soil, irrigated by surface irrigation, adopted appropriate deficit irrigation stage and optimal density (10–20 plant m−2). Crucially, we identified irrigation thresholds for fiber length, fiber strength, and Micronaire correlation analysis at 0.992, 0.882, and 0.897 of full irrigation, respectively, providing actionable irrigation strategies to main fiber quality under water-saving regimes.