Analysis on spring wheat spectrum characteristics influenced by dry-hot wind in Ningxia

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 λ 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.