宁夏春小麦干热风危害的光谱特征分析

摘要

In order to apply remote sensing technology to study the effects of the wheat dry-hot wind, the canopy spectrum on different hazard degree were measured before and after dry-hot wind occurring by Unspec-SC spectrum remote sensing instrument. By resampling the observed data, the spectrum response curves under different hazard degree were obtained. Classification of hazard degree of dry-hot wind and high spectral characteristics of each degree were studied combined with the observation of the opened awn rate, thousand-grain weight, etc. By constructing the RVI, NDVI and the other vegetation indices according to the spectral range of the EOS/MODIS visible channel, each hyperspectral vegetation index of wheat dry-hot wind level indicators and discriminant equation were established. The results showed that the reflectance spectrums of the different wheat dry-hot wind damages were certainly obvious differences. With the aggravation of wheat dry-hot wind, near-infrared platform were reduced, red valley elevation, slope of the red edge were declined, red edge position blue were shifted. The correlations were highly significant among wheat dry-hot wind hazard degree with RVI, NDVI, PVI, red edge vegetation index NDVI rededge and position X rep. Synthesized EOS MODIS corresponding channel value RVI, NDVI could reflect the difference of dry-hot wind hazard degree, and NDVI was more significant than RVI. It indicated that the use of EOS MODIS remote sensing data could distinguish the wheat dry-hot wind harm degree. The results provide a reference for monitoring and evaluation the wheat dry-hot wind hazard degree on large wheat field by remote sensing.%为利用遥感监测春小麦干热风受害程度,在春小麦发生干热风前后,利用Unispec-SC单通道光谱仪测定了春小麦群体不同干热风受害程度的高光谱.对光谱进行重采样,获得了不同干热风危害程度的光谱响应曲线.结合春小麦炸芒率、千粒质量等田间调查,对干热风危害程度进行了分级,研究了不同危害程度的高光谱特征.按照EOSMODIS可见光通道的波谱范围,构建了RVI、NDVI等多种指数.通过显著性分析,建立了判定春小麦干热风等级的高光谱植被指数指标和判别方程.结果表明,春小麦不同干热风受害程度的反射光谱差异明显.随着春小麦干热风的加重,近红外平台降低,红谷抬高,红边斜率下降,红边位置向短波方向移动.RVI、NDVI、PVI、红边植被指数NDVIRededge和红边位置λrep均与春小麦干热风受害等级关系极显著.模拟EOS MODIS相应通道值合成的RVI、NDVI指数能反映出不同干热风危害程度,NDVI指数比RVI指数反映更明显.研究表明利用EOS MODIS遥感资料可以分辨出大面积春小麦干热风受害程度,这为开展春小麦干热风危害的遥感监测评估提供了依据.