Effect of Moderate Drought in the Early Stage on Cotton Yield,Fiber Quality and Water Use Efficiency

Objective] A 2-year field experiment was conducted to determine the effect of a moderate drought regime in the early-stage on cotton yield, fiber quality and water use efficiency. Method] An experiment was set up in 2015 and 2016 on the Qingyuan Experimental Plot of Hebei Agricultural University based on a split plot design with two main plots: (1) conventional irrigation (W1) and (2) drought (limited irrigation before sowing with no irrigation during the growing period, W2). Three sub-plots with different cotton cultivars were established: CCRI 50 (early maturity), Nongdamian 601 (ND 601, moderate earliness), and Jimian 958 (JM 958, intermediate maturity). Result] (1) Drought stress affected the ratio of seasonal bolls. Under drought stress, the ratio of summer bolls decreased and that of autumn bolls increased. Because the precipitation peak in 2016 was higher than normal and mainly concentrated in July, which was later than in 2015, the ratio of autumn bolls increased in 2016. (2) Drought stress affected cotton yield but had no significant effect on fiber quality. Under moderate drought, the boll number per plant and boll weight of ND 601 and JM 958 decreased, the ratio of boll setting increased (P < 0.05), the boll weight of CCRI 50 increased, and the yields of all three cultivars decreased. Because CCRI 50 is an early-maturing cultivar and sensitive to water, its yield decreased significantly (41.0%). (3) Reducing irrigation by an appropriate amount was able to improve water use efficiency. The water use efficiencies of ND 601 and JM 958 averagely increased significantly, by 15.75% and 10.05%, respectively, between 2015 and 2016 under drought stress. The water use efficiency of CCRI 50 decreased significantly, by 15.9%, because of its early maturity and sensitivity to water stress. Conclusion] Moderate irrigation has a significant effect on yield, fiber quality, and water use efficiency. Cotton yield losses caused by water stress can be ameliorated by making the best use of natural precipitation and by increasing planting density.