荔枝花芽分化期叶片的光谱特征及其养分预测

为实现荔枝营养状况的快速监测，提高荔枝的精细施肥管理水平，服务华南荔枝的高产优质安全生产，研究了广州白云区荔枝花芽分化期冠层高光谱4 种变化形式的特性，结果表明荔枝秋梢冠层叶片光谱具有植物光谱共性。结合试验测得的冠层叶片生化养分数据（全氮、全磷、叶绿素、有机碳）分别与光谱反射率这4种形式作相关性分析。选择最显著相关的波段进行曲线拟合，结果表明：叶绿素、有机碳含量的最佳光谱诊断敏感波段分别是反射率一阶导数的 1 562 nm (r=0.8944)、1 720 nm (r=0.7827)，全氮、全磷的最佳光谱诊断敏感波段分别是倒数对数一阶导数的2 059 nm (r=0.8073)，1 347 nm (r=0.7575)；全氮、叶绿素、有机碳指数函数拟合最优（RMSE分别为0.002730, 0.008138和0.000416），全磷线性模型最优（RMSE=0.000336）。研究结果对华南精细荔枝果业的实施和果业环境保护都具有一定的指导意义。

Spectral characterization and nutrient prediction of litchi canopy leaves during flower bud differentiation

In order to achieve efficient monitoring of litchi nutrient and elevate the litchi management level in precision fertilizing, the research on the litchi nutrient and the spectral data of litchi canopy leaves during flower bud differentiation was performed serving to high yield and safety production of litchi planting in South China. The four forms of spectral data were analyzed. The results showed that the spectrum of litchi canopy leaves had common spectral characteristics of a plant. Based on the laboratory analysis on total nitrogen, total phosphorus, chlorophyll, and organic C, the relationships between spectral data and nutrients were investigated. Those spectral bands with the most significant correlation were chosen to create regression forecasting equations. The results showed that the first-order derivative of reflectance had the capability to estimate chlorophyll and organic C, and the sensitive diagnostic bands were at 1 562 nm (r=0.8944) and 1 720 nm (r=0.7827), respectively. The most-sensitive diagnostic spectral bands of total nitrogen and total phosphorus were the first-order derivative of reflectance spectrum at 2 059 nm (r=0.8073), 1 347 nm (r=0.7575), respectively. The exponential function was best for predicting the total nitrogen (RMSE=0.002730), chlorophyll (RMSE=0.008138) and organic C (RMSE=0.000416). Linear function fitted the prediction of total phosphorus best (RMSE=0.000336). The results have great significance on implementation of precision fruit agriculture and the environmental protection of litchi agriculture in South China.