Analysis dynamics and influence elements of winter wheat normalized difference vegetation index in mountain-foot plain

Normalized difference vegetation index(NDⅥ)is calculated from reflectance measurements in the red-NIR of the spectrum：NDⅥ =(NIR-R)／(NIR+R)．The amount of energy reflected from a plant in the visible and near inflared portion of the spectrum has been correlated to many crop characteristics．In this paper we have measured the daily and seasona1 NDⅥ dynamics and the effects of 1eaf area index (LAI)and wheat variety on NDⅥ ．The results show that with the development of winter wheat，NDVI changes，and during daytime，from sunrise to sunset，NDⅥ changes too．There is high correlation between NDVI and LAI and different wheat varieties have different NDV1．