Simultaneous and Nondestructive Diagnostics of Nitrogen/Magnesium/Potassium-deficient Cucumber Leaf Based on Chlorophyll Density Distribution Features

Nitrogen (N), magnesium (Mg), and potassium (K) deficiency all result in the decrease of chlorophyll density (CH.D) in cucumber leaf, but it is difficult to differentiate N/Mg/K-deficient leaves using CH.D. New indicators based on CH.D distribution features of cucumber leaf were proposed to simultaneously diagnose N/Mg/K-deficient cucumber plants. CH.D distribution map of cucumber leaves in N/Mg/K-deficient and control groups were determined non-destructively using hyperspectral image data. Compared with control group leaves, a decrease in CH.D could be observed on the whole area of N-deficient leaves, Mg-deficient leaves presented pixels with low CH.D between main leaf vein, and pixels with low CH.D could be observed at the border of K-deficient leaves. Distribution features were extracted from the CH.D distribution map and were employed to diagnose N/Mg/K-deficient leaves simultaneously, with the diagnostics rates of 96.67%. The result indicated that CH.D distribution features have potential for simultaneous diagnosing N/Mg/K-deficient leaves in practical applications.