Optimizing brackish water irrigation using magnetoelectric treatment for sustainable cotton cultivation in the arid region of southern Xinjiang

Brackish water irrigation is of great significance for alleviating water resource shortages and improving saline-alkali land utilization in southern Xinjiang, an arid region. This study conducted a two-year (2020–2021) field experiment considering two water quality treatments—brackish water (BW) and magnetoelectric brackish water (MW)—under five irrigation gradients: 262.5, 337.5, 412.5, 487.5, 562.5 mm. The effects of irrigation amount on cotton growth characteristics, photosynthetic parameters, abiotic stress resistance, yield, quality, and water use efficiency were analyzed. The results showed that MW treatment exhibited 1.41 %–8.50 % higher SPAD values compared to BW during the boll stage. The MW treatment increased the light compensation point by 2.46 %–37.29 % and reduced the light saturation point by 0.43 %–14.63 % relative to BW. Compared with BW, malondialdehyde levels under MW treatment were 2.25 %–9.77 % lower, whereas peroxidase, catalase, and superoxide dismutase levels were 1.98 %–11.09 %, 1.03 %–9.47 %, and 2.18 %–16.89 % higher. These physiological changes enhanced cotton's dry matter accumulation, which was 3.43 %–21.58 % higher under MW treatment. Considering the water use efficiency, the recommended irrigation quota for MW is 346.58–508.75 mm, and the theoretical yield can reach 4.90–5.84 t·ha −1 , 2.29 %–12.69 % higher than BW. Under the yield-dominated condition, the recommended irrigation quota for MW is 512.31–556.07 mm. The theoretical yield can reach 5.55–5.97 t·ha −1 , which provides a sustainable approach and theoretical guidance for the safe utilization of BW.