基于叶片SPAD的棉花氮营养指数估算研究

Nitrogen Nutrition Index of Cotton:Estimation Based on Leaf SPAD

为了探究不同施氮处理对棉花叶片SPAD值、生物量和氮营养指数(NNI)的影响,通过两年田间试验,设置5个施氮水平(即0、120、240、360、480 kg/hm^(2)),开展棉花叶片SPAD值、氮素吸收分配规律和生物量变化的研究。研究结果发现:棉叶SPAD值随施氮量增加呈增加趋势,在N4处理下获得最大值;建立棉花氮浓度稀释模型:N_(c)=3.02W_(max)^(-0.24),分析表明棉叶SPAD与NNI之间呈正相关关系,相关系数R^(2)为0.05~0.74;经验证,棉花不同生育时期的模型模拟性能较好,出苗后97天时相关系数达到最大。棉花叶片SPAD值与临界氮浓度存在显著的正相关关系,可以作为棉花氮营养诊断的指标。

To explore the effects of different nitrogen application treatments on the SPAD value,biomass and nitrogen nutrition index(NNI)of cotton leaves,through a 2-year field experiment,5 nitrogen application levels(0,120,240,360,480 kg/hm^(2))were set to study the SPAD value of cotton leaves,the law of nitrogen absorption and distribution,and the change of biomass.The results showed that the SPAD value of cotton leaves increased with the increase of nitrogen application rate,and reached the maximum value under N4 treatment.The dilution model of cotton nitrogen concentration was established:N c=3.02W_(max)^(-0.24).The analysis showed that there was a positive correlation between SPAD and NNI of cotton leaves,and the correlation coefficient R^(2) was 0.05-0.74.It is proved that the simulation performance of the model at different growth stages of cotton is relatively good,and the correlation coefficient could reach the maximum at 97 days after seedling emergence.There is a significant positive correlation between the SPAD value of cotton leaves and the critical nitrogen concentration,which can be used as an index for cotton nitrogen nutrition diagnosis.