科研之友
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摘要
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 R(Normal) > R(Low) > R(High) at 550 nm 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, r(Normal) > r(High) > r(Low). Analysis of the relations at different growth stages showed on the band of 400 similar to 1000 nm 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 550 nm. In order to detect the chlorophyll content of corn, 558 nm, 667 nm, 714 nm and 912 nm 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, 558 nm, 667 nm and 714 nm 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 (r(2) = 0.80) and trumpet stage (r(2) = 0.66) respectively which were higher than PLSR. It also provided a feasible method to detect chlorophyll content non-destructively.
- 出版日期2010-2
- 单位中国农业大学
