烟蚜为害特征的高光谱比较

Comparison of hyperspectral characteristics in tobacco aphid damage.

利用手持式高光谱仪测定不同蚜量为害后烟草冠层光谱反射率的变化,同时使用叶绿素计测量叶绿素含量。结果表明,烟草光谱呈现标准植被光谱曲线,烟蚜Myzuspersicae(Sulzer)为害造成烟草光谱反射率下降,近红外波段反射率下降更为明显。和健康烟株相比,轻度(单株顶尖和上部5片叶蚜量≤15头)、中度(15头<单株顶尖和上部5片叶蚜量≤50头)、重度(单株顶尖和上部5片叶蚜量>50头)危害在绿光波段反射率分别下降12%,27%,52%,在近红外波段分别下降15%,20%,38%。对反射率曲线进行微分分析,健康烟株、轻度、中度和重度为害后的一阶导数最大值分别为0.031,0.022,0.026和0.019,其值随着蚜量增加而下降,对应的波长重度为害为718.45nm,其它为716.91nm,红边位置向长波方向移动1.46nm。蓝光、绿光、红光和近红外4个波段反射率和叶绿素含量SPAD值存在良好的线性回归关系,相关系数都达到极显著,绿光波段反射率对叶绿素含量的回归关系尤为显著;同时SPAD值越大,光谱反射率越高。该研究对于应用遥感技术大面积监测烟草生产中病虫害的发生,确定防治适期以及适宜的防治措施具有重要的应用前景。

Using ASD Hand-held Spectroradiometers and Chlorophyll Meter SPAD-502 measured the canopy reflectance of tobacco damaged by the tobacco aphid Myzus persicae （Sulzer） and the chlorophyll content of tobacco. The results showed that the spectrum of tobacco is a standard vegetation spectrum and the reflectance decreased due to the damage of tobacco aphid, especially in the near infrared band. Based on the results of field investigation, we divided the aphid damage into four degrees： healthy, gentle, moderate and severe. The reflectance of light, moderate and severe decreased 12% ,27% ,52% and 15% ,20% ,38% in green and near infrared band respectively compare to the healthy. With the damage of tobacco aphid, the maximal value of first derivative is 0.031, 0.022, 0.026 and 0.019, moreover, the spectrum move to the direction of long wave. The correlation between all the four bands reflectance and the SPAD value are significant. This research is prospective for applying remote sensing monitoring the insect pests and diseases in tobacco and determining the appropriate control time and methods.