The combination of limited irrigation and high plant density optimizes canopy structure and improves the water use efficiency of cotton

Abstract

Increasing plant density under insufficiency or deficit irrigation is considered a new water-saving technique in cotton production, especially in Xinjiang, China, an arid area with a short growing period. Increasing plant density reduces light intensity within the canopy; therefore, we hypothesized that resource use efficiency may be the main factor affecting cotton yield and water use efficiency under limited irrigation conditions. To test this hypothesis, 2-year field experiments were conducted to explore the effects of two irrigation patterns (I500, conventional irrigation; I425, limited irrigation) and three planting densities (D12, 12; D24, 24; D36, 36 plants m−2) on cotton yield, fiber quality, light interception rate, canopy photosynthesis and irrigation water use efficiency (IWUE). I425D36 raised yield and IWUE by 1.40–22.4% and 13.4–34.5%, respectively, but it did not affect fiber quality compared with other treatments. Further, I425D36 increased the leaf area index and the top- and middle-canopy light interception rates after 105 days after sowing, which improved the canopy apparent photosynthetic rate. Seed cotton yield was associated with leaf area index and the top- and bottom-canopy light interception rates. We conclude that irrigation of cotton with limited irrigation at a 425-mm level and a plant density at 36 plants m−2 had significant benefits in terms of economized irrigation without reducing yield in arid areas.