| The staple food of potato start strategy in China, making it the fourth largest staple food. The yield of potato has important significance in ensuring food security in our country. The effect of nitrogen fertilizer on the yield and quality of potato is very important. It is essential to use nitrogen fertilizer scientifically and accurately. With the development of precision agriculture, the researchers put high value on the application of spectrum technology and digital image technology in agriculture. Potato is researched in this study. Hyperspectral technology and digital image technology are measured in potato leaves to monitor the potato growth and nitrogen status. There are 6 different application levels of nitrogen N0-N6 in two year pot experiment. Hyperspectral remote sensing technology, digital image technology and physiological index of testing technology were been used in this experiment. The change of spectral reflectance, canopy digital images, growth parameters, physiological indexes and nitrogen status of potato leaves under different nitrogen levels were analyzed. Uses the correlation analysis method carries on the statistical analysis to spectral index, digital image index and growth parameters, physiological indexes and the nitrogen status of the leaves. The spectral index and the digital image index were selected to reflect the growth status and nitrogen status of potato.The verification feasibility of application by spectrum technology and digital image technology on potato growth potential and nitrogen nutrition monitoring. Provide a research idea and technical support for potato production and nitrogen nutrition monitoring.The main conclusions of research were as follows:1. The growth parameters, physiological indexes, leaf nitrogen status, spectral indices and digital image indexes were researched under different nitrogen levels. With the increasing of nitrogen applied, the fresh weight per plant, dry matter per plant, SPAD and the nitrogen accumulation of potato leaves were increased, the yield, leaf area of potato, nitrate content and nitrate reductase activity increased first and then decreased. The spectral reflectance of potato leaves was decreased in 350nm-680nm with increasing nitrogen rates. The spectral reflectance of potato leaves was increased in 700nm-1050nm with increasing nitrogen rates. With the increasing of nitrogen applied. The spectral reflectance of potato leaves appeared red shift phenomenon, the REP (red edge position), Lwidth(red edge width, FD_Max(the maximum value of the first derivative) were increased, while the Lo (Red Valley location) decreased. The potato digital index of G/B, (G-B)/(R+G+B) showed a decreasing trend, while the B/(R+G+B) is increased.2. The correlation analysis of potato growth parameters, physiological indexes, leaf nitrogen status and spectral indices and digital image indexes were researched to explore the possibility application of spectrum technology and digital image technology in the monitoring of nitrogen status and growth status in potato. The results showed that the highest correlation coefficient between origin spectrum and growth parameters, physiological indexes, leaf nitrogen accumulation were -0.93,-0.93 and 0.87; The highest correlation coefficient between first derivative spectrum and growth parameters, physiological indexes, leaf nitrogen accumulation were 0.98, 0.97 and 0.96. A negative and positive correlation between original spectrum and growth parameters, physiological indexes, leaf nitrogen accumulation in 520nm-700nm and 740nm-1050nm respectively. There were better correlation coefficient between the REP (red edge position), Lwidth(red edge width) of red edge parameter and growth parameters, physiological indexes, leaf nitrogen accumulation. The correlation of REP and Lwidth with growth parameters and physiological indexes reached a significant level, there was an extremely significant correlation between REP, Lwidth and leaf nitrogen accumulation. There were significant correlation between 11 vegetation index and growth parameters in 12 vegetation index. The correlation between vegetation index and physiological index, leaf nitrogen accumulation reached extremely significant level. There were 8 spectral parameters based on the spectral position with growth parameters, physiological index reached a significantly correlation, and a very significantly correlation with leaf nitrogen accumulation. There were significant correlation between the G/B, B/(R+G+B), (G-B) /(R+G+B) of digital image index and growth parameters, physiological indexes, leaf nitrogen accumulation.3. The spectrum of 520nm-700nm and 740nm-1050nm can be used for monitoring the status of potato growth and nitrogen nutrition through analyzing the correlation of each index. The spectral characteristic variables of the red edge parameters, vegetation index, REP, modified normalized difference index, area of red edge and blue border area normalization value can be used as the potato growth and nitrogen nutrition status monitoring index. G/B and B/(R+G+B) in digital image index could be a potato growth and leaf nitrogen accumulation monitoring and prediction index. |
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