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Chinese Agricultural Science Bulletin ›› 2014, Vol. 30 ›› Issue (3): 85-90.doi: 10.11924/j.issn.1000-6850.2013-0800

Special Issue: 玉米

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Monitoring Leaf Nitrogen Accumulation in Summer Maize with Canopy Reflectance Spectra

  

  • Received:2013-03-21 Revised:2013-04-23 Online:2014-01-25 Published:2014-01-25

Abstract: To realize non-destructive and quick assessment of leaf nitrogen status in summer maize, two field experiments were conducted with different maize cultivars and nitrogen levels across two growing season, and time-course measurements were taken on canopy spectral reflectance and leaf nitrogen accumulation during the period of experiment. Base on the canopy reflectance and derived vegetation index, we analyzed the quantitative relationships between leaf nitrogen accumulation and canopy reflectance in different maize cultivars under varied nitrogen rates, and put forward the sensitive parameters and monitoring equation for leaf nitrogen accumulation. The results showed that, leaf canopy nitrogen accumulation in maize increased with increasing nitrogen rates. Wavelengths at 460-670 nm and 780-1100 nm were sensitive to leaf nitrogen accumulation for nitrogen diagnosis. Leaf nitrogen accumulation was highly correlated with normalized difference vegetation index (NDVI), modified simple ratio (MSR), optimal soil-adjusted vegetation index (OSAVI), modified soil-adjusted vegetation index (MSAVI), soil-adjusted vegetation index (SAVI), respectively. Comparing the R2 and standard error of regression model, the spectral index of OSAVI was the test parameter for predicting leaf nitrogen accumulation. The monitoring models were tested with an independent dataset, and the predictive precision (r) was 0.6745, and RMSE was 1.2368. It was concluded that leaf nitrogen accumulation in summer maize could be monitored by key vegetation indices, with more reliable estimation from OSAVI.