Abstract: A soil column culture experiment was conducted under the ecological an d climatic conditions of Xinjiang to study the effects of water storage in deepe r (>60 cm) soil layers on the root physiological characteristics and leaf photo synthetic traits of cotton variety Xinluzao 13. Two treatments were installed, i.e., well-watered and no watering. The moisture content in plough layer was controlled at 70%±5% and 55%±5% of field capacity by drip irrigation under mulch d uring growth season. It was shown that the water storage in deeper soil layers e nhanced the SOD activity and the vigor of cotton root, and increased the water u se efficiency of plant as well as the leaf water potential, chlorophyll content, and net photosynthesis rate, which finally led to a higher yield of seed cotton and higher water use efficiency. Under well-watered condition and when the moi sture content in plough layer was maintained at 55% of field capacity, the senes cence of roots in middle and lower soil layers was slower, and the higher root v igor compensated the negative effects of impaired photosynthesis caused by water deficit to some extent. The yield of seed cotton was lower when the moisture co ntent in plough layer was maintained at 55% of field capacity than at 70% of fie ld capacity, but no significant difference was observed in the water use efficie ncy. Our results emphasized the importance of pre-sowing irrigation in winter or in spring to increase the water storage of deeper soil layers. In addition, pro per cultivation practices and less frequent drip irrigation (longer intervals be tween successive rounds of irrigation) were also essential for conserving irriga tion water and achieving higher yield.

Key words: wheat, drought resistance, GGE biplot, drought-resistance coefficient, subordinate function.