Abstract: 【Objective】 To clarify the regulation mechanism of photosynthetic characteristics and yield of cotton under wide-row spacing with high-density conditions in the hope of providing theoretical basis and practical guidance for the management of high-efficiency nitrogen fertilizer.【Methods】 By taking the early-maturing cotton cultivar Xinluzao 64 as the test variety, this paper measured the gas exchange parameters, chlorophyll fluorescence parameters, yield and yield components of cotton at the yield formation stage under 5 different treatments, namely nitrogen application rates of N₀ (kg/667 m²), N₈ (8 kg/667 m²), N₁₆ (16 kg/667 m²), N₂₄ (24 kg/667 m²) and N₃₂ (32 kg/667 m²).【Results】 There was no significant difference in the single boll weight under various nitrogen application rates; the total number of bolls and yield treated by N₁₆ and N₂₄ were relatively high, while those by N₀ and N₈ treatments were the lowest. From the full-bloom stage to the later stage of boll development, the net photosynthetic rates of cotton treated by N₁₆, N₂₄ and N₃₂ were always at a high level. The transpiration rates and stomatal conductance of N₁₆ and N₂₄ treatments at the boll development stage were much lower than those of N₃₂ treatment were, yet their intercellular CO₂ concentrations were significantly higher than that of N₃₂ treatment. From the full-bloom stage to the boll development stage, no significant difference was observed in the maximum photochemical efficiencies of various nitrogen application treatments except that the maximum photochemical efficiencies of N₀ and N₈ treatments were significantly lower than those of other treatments at the later stage of boll development; the actual photochemical efficiencies and photochemical quenching coefficients of N₁₆ and N₂₄ treatments were high in the later stage of boll development. Furthermore, the non-photochemical quenching coefficient of N₁₆ treatment was significantly lower than those of N₂₄ and N₃₂ treatments.【Conclusion】 Under wide-row spacing with high-density conditions, a nitrogen application rate of 16-24 kg/667 m² contributes to the high photosynthetic capacity of leaves at the flowering and boll setting stages of cotton, as well as the best utilization of light energy by leaves in the later stage of boll development, thereby greatly raising the yield of cotton.

Key words: cotton; wide-row spacing with high density; nitrogen application rate; photosynthesis; yield

摘要： 【目的】 研究施氮量对等行距密植棉花光合特性及产量的调节机制,为等行距密植模式下棉花高效氮肥管理提供理论依据和实践指导。【方法】 以早熟棉品种新陆早64号为材料,设5个施氮量(N)处理:N₀(0 kg/667 m²)、N₈(8 kg/667 m²)、N₁₆(16 kg/667 m²)、N₂₄(24 kg/667 m²)和N₃₂(32 kg/667 m²),测定棉花关键生育时期的气体交换参数、叶绿素荧光参数、产量及其构成因子。【结果】 不同施氮量条件下单铃重无显著差异,总铃数和产量以N₁₆和N₂₄处理较高、N₀和N₈处理最低。盛花至盛铃后期,N₁₆、N₂₄和N₃₂处理的净光合速率始终均处于较高水平,但N₁₆和N₂₄处理盛铃期的蒸腾速率和气孔导度显著低于N₃₂处理,胞间CO₂浓度显著高于N₃₂处理。不同施氮量处理的最大光化学效率在盛花至盛铃期无显著差异,但N₀和N₈处理的最大光化学效率在盛铃后期显著低于其他处理,N₁₆和N₂₄处理的实际光化学效率和光化学猝灭系数在盛铃后期保持较高值,且N₁₆处理的非光化学猝灭系数在盛铃至盛铃后期显著低于N₂₄和N₃₂处理。【结论】 在等行距密植条件下,施氮16~24 kg/667 m²有利于保持花铃期叶片较高的光合能力,维持盛铃后期叶片对光能的利用,获得较高的棉花产量。

关键词: 棉花, 等行距密植, 施氮量, 光合作用, 产量