初花后土壤碱解氮浓度对棉花生物量和氮素累积特征的影响

试验于2009—2010年分别在江苏省棉花科技示范基地东台市(120°19'' E, 32°52'' N)和大丰市(120°28'' E，33°12'' N)进行。设置6个水平(0、150、300、375、450和600 kg hm^–2)施氮量，研究土壤碱解氮浓度变化特征及对棉花生物量和氮素累积特征的影响。结果表明，棉花初花后土壤碱解氮浓度的动态变化可用三次函数方程模拟，棉花生物量、氮素累积动态可用Logistic方程拟合；土壤碱解氮浓度快速下降期的平均速率、持续时间分别与棉株生物量、氮素快速累积期的最大相对累积速率、持续时间有较高的相关性；在375 kg hm^–2施氮量下，土壤碱解氮浓度快速下降期具最佳平均速率和持续时间，棉株生物量和氮素快速累积期有最优的累积特征值，棉花具有最优的生物量、氮素累积特征值，棉花产量最高、综合品质最优。高施氮量和低施氮量皆不利于棉花生物量和氮素的累积。因此，适宜的施氮量及施氮运筹可调节棉花初花后土壤碱解氮浓度的动态变化，优化棉花生物量和氮素的累积以及产量和品质。

Effects of Soil Alkaline Hydrolyzed Nitrogen Concentration on Biomass and Nitrogen Accumulation Eigenvalues of Cotton after Initial Flowering

Two field experiments were conducted at Dongtai City (120°19'' E, 32°52'' N) and Dafeng City (120°28'' E, 33°12'' N) , Jiangsu province, in 2009 and 2010, severally. Six nitrogen rates (0, 150, 300, 375, 450, and 600 kg ha^–1) were set to study the effects of soil alkaline hydrolyzed nitrogen concentration (SAHNC) on biomass and nitrogen accumulation of cotton. The result showed that, the change of SAHNC could be simulated with a cubic function, biomass and nitrogen accumulation of cotton could be simulated with logistic formula; average rate and duration of the SAHNC’s speedy reducing had significant correlation with the biggest rate and duration of speedy accumulation period of cotton’s biomass and nitrogen. Under the nitrogen applied level of 375 kg ha–1, the SAHNC speedy reducing had optimal average rate and duration, cotton plant had optimal biomass and nitrogen accumulation eigenvalues, and had the highest fiber yield and optimal fiber qualities. Too high or too low nitrogen application was not benefit for biomass and nitrogen accumulation of cotton. Therefore, optimal nitrogen applied level and nitrogen applied strategy can adjust the dynamic change of SAHNC, and be beneficial for optimizing biomass and nitrogen accumulation eigenvalue and the lint yield and qualities after initial flowering.