[Potato Spectrum and the Digital Image Feature Parameters on the Response of the Nitrogen Level and Its Application].

In order to know the potatoes nitrogen situation rapidly and accurately, promoting the efficient use of nitrogen fertilizer on the potatoes. Using the feature of portable hyperspectral spectrometer, digital cameras and SPAD-502 chlorophyll meter to abtain the potato digital indicators, leaf spectral and SPAD. Analysing the change status of digital indicators, leaf spectral index, SPAD and production of potatoes under different nitrogen levels in two key periods. Analysing the correlation between canopy image, leaf spectral and SPAD and production, with SPAD as auxiliary validation index, nitrogen fertilizer efficiency evaluation of yield to make sure potato canopy image under the most economic nitrogen application levels and leaf spectral’s critical value to explore the methods of nitrogen nutrition diagnosis quickly and simply. The results show: (1)With nitrogen levels increased, potato tuber formation stage and tuber bulking stage leaf spectral reflectance is the emergence of the "red shift" phenomenon, and the red edge parameters REP, Lwidth, FD_Max increased, Lo decreased. (2)With the nitrogen levels increased, potatoes tuber formation stage and tuber bulking stage digital indicators G/B, (G-B)/(R+G+B) decreased gradually, B/(R+G+B) increased gradually. (3) with the increase of nitrogen application rate SPAD is increased.It is obvious low nitrogen levels increase production with nitrogen increased. It is not obvious the high level of nitrogen stimulation effect. Potato canopy image, leaf spectral and red edge parameters have good correlation with SPAD value and productions, establishing the index evaluation of nitrogen nutrition abundance or lack of quantitative standard of potatoes. Indicating digital image and spectrum technology to nitrogen nutrition diagnosis of potatoes is feasible, provide research ideas and technical support for the potato accurate monitoring of nitrogen nutrition.