Optimal planting pattern of cotton is regulated by irrigation amount under mulch drip irrigation

OBJECTIVE: It is of great importance to explore agronomic management measures for water conservation and cotton yield in arid areas. METHODS: A four–year field experiment was conducted to evaluate cotton yield and soil water consumption under four row spacing configurations (high/low density with 66+10 cm wide, narrow row spacing, RS(66+10H) and RS(66+10L); high/low density with 76 cm equal row spacing, RS(76)H and RS(76)L) and two irrigation amounts (CI:conventional drip irrigation; LI:limited drip irrigation) during the growing seasons in Shihezi, Xinjiang. RESULTS: A quadratic relationship was observed between the maximum LAI (LAI(max)) and seed yield. Canopy apparent transpiration rate(CAT), daily water consumption intensity (DWCI) and crop evapotranspiration (ET(C)) were positively and linearly correlated with LAI. The seed yields, lint yields, and ET(C) under CI were 6.6–18.3%,7.1–20.8% and 22.9–32.6%higher than those observed under LI, respectively. The RS(66+10H) under CI had the highest seed and lint yields. RS(76)L had an optimum LAI(max) range, which ensured a higher canopy apparent photosynthesis and daily dry matter accumulation and reached the same yield level as RS(66+10H); however, soil water consumption in RS(76)L was reduced ET(C) by 51–60 mm at a depth of 20–60 cm at a radius of 19–38 cm from the cotton row,and water use efficiency increased by 5.6–8.3%compared to RS(66+10H) under CI. CONCLUSION: A 5.0<LAI(max)<5.5 is optimum for cotton production in northern Xinjiang, and RS(76)L under CI is recommended for high yield and can further reduce water consumption. Under LI, the seed and lint yield of RS(66+10H) were 3.7–6.0% and 4.6–6.9% higher than those of RS(76)L, respectively. In addition, high-density planting can exploit the potential of soil water to increase cotton yields under water shortage conditions.