基于冠层尺度的花生叶片糖氮比高光谱监测

Hyperspectral Monitoring of Sugar and Nitrogen Ratio in Peanut Leafat Canopy Scale

摘要:

通过分析花生叶片糖氮比与冠层高光谱参数的定量关系，确立花生叶片糖氮比的定量监测模型。选用丰花1号花生品种作为研究对象，在不同施氮水平下进行了田间试验，于花生不同生育时期采集田间冠层高光谱数据并测定叶片糖氮比，进而分析建立冠层高光谱参数与叶片糖氮比的回归模型。结果表明，花生叶片糖氮比随生育进程呈“高-低-高-低”的动态变化模式；从出苗到结荚之前，均是施氮处理低于对照，在花生收获期，施氮处理高于对照。利用高光谱参数对叶片糖氮比进行监测的适宜时期是出苗期到饱果成熟期，开花下针期冠层植被指数与糖氮比相关性均达显著水平，且利用DVI建立的回归方程更为可靠，R2为0.866~0.993，SE为0.026~0.083。花生结荚期以后，利用EVI建立的回归方程更可靠，R2为0.893~0.927，SE为0.054~0.082。通过模拟值与实测值的拟合，发现DVI和EVI两个特征光谱参数表现良好，可分别对生长前期和后期的花生叶片糖氮比进行可靠监测。

Abstract:

Carbon and nitrogen metabolism of plants reflect the physiological status and growth vigor, which is the physiological basis of peanut yield and quality formation. Therefore monitoring the ratio of sugar to nitrogen in real-times important for growth diagnosis and nitrogen management for peanut plant. The main purpose of this study was to establish a quantitative model for monitoring the ratio of sugar to nitrogen in peanut leaves, through analyzing the relationship between the ratio of sugar to nitrogen and the canopy hyper-spectral parameters. The experiment was carried out on peanut variety NO.1. Different nitrogen level treatments were applied, and canopy hyper-spectral parameters were collected in different growth stages of peanut. Then the regression model of canopy hyper-spectral parameters and leaf ration of sugar to nitrogen was established The results showed that peanut leaf sugar to nitrogen ratio was in the dynamic change pattern of “high-low-high-low” within the growth process. And from seedling to pod, peanut leaf sugar to nitrogen ratio for all N treatment group was lower than the control group, and in the peanut harvest period N treatment, it was the opposite. The most suitable period for monitoring hyper-spectral parameter of leaf sugar to nitrogen ratio is seedling stage to full fruit maturity stage. Flowering and knit stitch stages vegetation index and the ratio of sugar to nitrogen correlation reached a significant level, and in these two stages, the regression equation established by DVI was more reliable. The R2 value of it was 0.866~0.993, and SE value was 0.026~0.083. After the peanut pod, using the EVI to establish regression equation is more reliable. The R2 value was 0.893~0.927, and SE value is 0.054~0.082. It is found that the characteristics DVI and EVI have the best performance, which could be used to monitor the ratio of sugar to nitrogen in the early and late growth stages reliably.