DETCTION OF CORN CHLOROPHYLL CONTENT USING CANOPY SPECTRAL REFLECTANCE
The canopy spectral reflectance and chlorophyll content of corn were measured and analyzed under different nitrogen treatments. The characteristics of canopy spectral reflectance were described at different stages. Investigation of canopy reflectance under the different nitrogen treatment showed that RNormal>RLow>RHigh at 550nm at shooting stage. At trumpet stage, the canopy reflectance in low fertilizing region was higher than others were in the visible region and the corn canopy reflectance of normal fertilizing region was same as high fertilizing region. It was obvious that the over-fertilizer could not help to increase the corn nitrogen uptake. The correlation between spectral reflectance and chlorophyll content was discussed based on different growth stages and different nitrogen levels. The results showed the relation under normal nitrogen treatment was better than others were, rNormal>rHigh>rLow. Analysis of the relations at different growth stages showed on the band of 400~1000nm the absolute value of correlation coefficient increased and reached the maximum at shooting stage, it decreased until anthesis-silking stage, and then rebounded at milking stage. The positive correlations were found at shooting and milking stage, while negative correlations were found at tilling, trumpet and anthesis-silking stage. It was indicated that the sensitive stages to detect the chlorophyll content were shooting and trumpet stage which with high absolute value of correlation coefficient above 0.6 around 550nm. In order to detect the chlorophyll content of corn, 558nm, 667nm, 714nm and 912nm were selected to establish the MLR model and PLSR model. The results showed that PLSR was more capable of building chlorophyll content models reflecting correct relations among multi-variables compared with MLR. In the meanwhile, 558nm, 667nm and 714nm were selected to build different vegetation indices such as GDVI, GRVI, NDCI, DVI, RVI and NDVI. The correlation coefficient between DVI and chlorophyll content was higher than others were and DVI was used to establish binomial model and exponential model at shooting stage (r2=0.80) and trumpet stage (r2=0.66) respectively which were higher than PLSR. It also provided a feasible method to detect chlorophyll content non-destructively.
Spectral reflectance Chlorophyll detection Vegetation indez
Sun Hong Li Minzan Zhang Yane Zhao Yong Wang Haihua
“Key Laboratory of Modern Precision Agriculture System Integration ResearchMinistry of Education,China Agricultural University,Beijing 100083,PR China
国际会议
北京
英文
1-10
2009-10-14（万方平台首次上网日期，不代表论文的发表时间）