A Kind of Rice Nitrogen Status Rapid Diagnostic Tool

Using data from three deformation positions (680 nm, 730 nm, and 765 nm) of spectral reflectance and derivative spectra curves from red to near infrared spectral bands, red edge reflectance spect ra index was developed. Nitrogen contents of rice canopy leaves were found to be significantly correlated with the red edge reflectance spectra index values at 0.01 probability level for different rice growth stages and genotypes studied. Four models established for four rice growth stages were used to predict the nitrogen content of canopy leaves. Significant correlations were found between measured nitrogen contents and predicted nitrogen contents with high coefficient of determination (R2 = 0.97) at 0.01 probability level. Based on the four field experiments, we developed a new rice nitrogen status rapid diagnostic meter. The working principle of the meter was introduced, and the measuring accuracy of the meter was analyzed. Results showed that the precision of nitrogen status rapid diagnostic meter for predicting nitrogen content was more than 80% at tiller stage and more than 90% at booting stage at 0.01 probability level. The nitrogen status rapid diagnostic meter appears to be a promising tool for rapid, on-farm analysis of rice nitrogen status.