Objective To explore the coupling effects of spring irrigation quota and growth-stage irrigation level on the growth, yield and fiber quality formation of cotton in saline cotton fields of southern Xinjiang, so as to provide theoretical basis for optimizing regional cotton irrigation regimes.
Methods A split-plot experimental design was adopted. Two spring irrigation quotas of (1800 m3/hm2) (T1) and (2250 m3/hm2) (T2), as well as four growth-stage irrigation quotas of 2250, 3375, 4500 and 5625 m3/hm2(W1–W4) were set up. Cotton growth indicators, dry matter accumulation, seed cotton yield and fiber quality under each treatment were measured, and the regulatory differences among coupled drip irrigation treatments were compared and analyzed.
Results The increase of irrigation quota during the growth period significantly promoted the growth of cotton plant height, stem diameter and leaf area. The T2W4 treatment achieved the optimal values of all growth indicators, reaching 84.37 cm, 11.87 mm and (2177.25 m3/hm2) respectively. Under the same spring irrigation level, the dry matter accumulation followed the order of (W4>W3>W2>W1); the T2W4 treatment obtained the highest seed cotton yield of (6321 m3/hm2).
Conclusion The spring irrigation quota of (2250 m3/hm2) (T2) was more conducive to the vegetative growth and dry matter accumulation of cotton than (1800 m3/hm2) (T1), and significantly improved single boll weight, lint percentage and seed cotton yield. Under the same spring irrigation level, cotton yield rose with the increase of growth-stage irrigation quota, while fiber length, uniformity index and breaking tenacity showed a declining trend. In practical production, a balance should be struck between yield and fiber quality. The T2W4 combination is the optimal coupled irrigation scheme for pursuing high yield in the Xiaohaizi Irrigation Area; if high fiber grade is required, the irrigation quota in the growth period should be appropriately reduced.
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