盐碱旱地减氮增施叶肥对棉花光合特征产量和品质的影响

【目的】 滨海盐碱旱地条件下,研究不同水平减施氮肥配合增施叶面肥对棉花光合特征、产量和品质的影响,分析增施叶面肥对棉花氮肥减施的补偿效应,研究棉花稳产前提下的氮肥减施补偿策略,为滨海盐碱旱地棉花减肥增效规模化种植提供数据支持和理论依据。【方法】 设置施氮量分别为0(CK)、60(N₁)、90(N₂)、120(N₃)、150(N₄)、180(N₅)、225(N₆) kg/hm² 7个水平,其中N₁~N₄喷施叶面肥4次,测定处理植株农艺性状、主茎叶SPAD值、光合特征指标、籽棉产量和纤维品质指标。【结果】 花铃期处理棉花主茎叶SPAD值随氮肥施用量的减少而降低,增施叶面肥后各减氮处理主茎叶SPAD值差异不显著;主茎叶净光合速率(Pn)和蒸腾速率(Tr)随施氮量的减少而降低,胞间CO₂浓度(Ci)逐渐增加;施氮量225~60 kg/hm²时,籽棉产量、单株铃数、单铃重和衣分随氮肥施用量减少而降低,其中施氮量90~150 kg/hm²增施叶面肥处理与180 kg/hm²处理间的籽棉产量差异不显著;纤维断裂比强度和整齐度随氮肥用量的减少先升高再降低,马克隆值逐渐升高,对纤维长度和伸长率没有显著影响。【结论】 盐碱旱地减施氮肥配合增施叶面肥,对棉花主茎叶片光合速率、籽棉产量及纤维品质的负面影响有一定减缓作用,“减氮肥+增叶肥”施肥模式有助于产量稳定,减少氮肥投入,降低环境污染。

Effects of Reduced Nitrogen and Increased Leaf Fertilizer Application on Photosynthetic Characteristics,Yield and Quality of Cotton in Saline-alkali Dryland

【Objective】 To study the effects of reducing nitrogen fertilizer combined with increasing foliar fertilizer on photosynthetic parameters, yield and quality of cotton under the saline and dry land conditions in the hope of assessing the compensation effect of increasing foliar fertilizer on reduced nitrogen fertilizer of cotton. 【Method】 There were 7 nitrogen application rates: 0 (CK), 60 (N₁), 90 (N₂), 120 (N₃), 150 (N₄), 180 (N₅), and 225 (N₆) kg/hm². Among them, N₁-N₄ was sprayed four times. Then leaf SPAD values, photosynthetic parameters, plant agronomic traits, yield and fiber quality were measured. 【Result】 The leaf SPAD value at the flowering and boll-setting stage decreased with the reduction of the nitrogen application. No differences were found in the SPAD value between N₁, N₂, N₃ and N₄ after the application of foliar fertilizer. Leaf net photosynthetic rate (Pn) and Transpiration rate (Tr) decreased with the reduction of nitrogen application rate, while the intercellular CO₂ concentration (Ci) gradually increased. In general, cotton yield, boll number per plant, boll weight and lint percentage decreased with the reduction of nitrogen application. No differences in cotton yield were found among N₂, N₃, N₄ and N₅. Fiber quality parameters specific breaking strength and uniformity index increased first and then decreased, micron value decreased along with the reduction of nitrogen, but no significant differences were found in fiber length and elongation rate. 【Conclusion】 The application of nitrogen fertilizer in saline-alkali dry land combined with the application of foliar fertilizer has a certain effect on the negative effects of photosynthetic rate, seed cotton yield and fiber quality. This technique might be helpful to reduce nitrogen fertilizer input, stabilize cotton production and reduce environmental pollution.