Winter wheat（Triticum aestivum L.） is one of the most important crops in China.Severe epidemic of yellow rust is the main reason of winter wheat yield loss and quality degradation.Hyperspectral remote sensing

acquiring images in narrow and continuous spectral bands

has been recognized as a reliable method for crop health monitoring.In researches related to hyperspectral data analysis

the region of the red-near infrared（NIR） transition has been shown to have high information content for vegetation status.This region is generally referred to as the "red edge".It represents the region of abrupt change in leaf reflectance between 680 and 780nm caused by the combined effects of strong chlorophyll absorption in the red wavelengths and high reflectance in the NIR wavelengths due to leaf internal scattering.In this article

the first derivative of red edge spectra（Dred） was analyzed for winter wheat with different stripe rust disease severity.Results indicated Dred had characteristic of multi-peak;for diseased wheat

the front peak（700nm） was more dominant and the back peak（725—735nm） was more flat;red edge position（REP） shifted towards shorter wavelength;both maximum value of Dred（Dr） and sum of Dred（Sr） decreased.Two new red-edge indices（DSr

Ar） were proposed based on the difference in the shape of Dred between healthy and diseased wheat.DSr

an index describing thinness of Dred

was defined by the ratio of Dr and Sr.When winter wheat is healthy（diseased）

Dred is very steep（flat） and hence DSr is very large（small）.Ar

an index describing asymmetry of Dred

was defined as（S2-S1）/（S2+S1）

where S1 and S2 was the sum of Dred in 680—700 nm and 701—775 nm respectively

which corresponded to the spectral region adjacent to front peak and back peak.When winter wheat is healthy（diseased）

the difference between S2 and S1 is very significant（non-significant） and hence Ar is very large（small）.Compared to other conventional red edge indices

DSr and Ar can predict stripe rust disease severity more accurately.