Nitrogen Status Diagnosis of Fertilized Alfalfa during Budding Stage Using Digital Photography Analysis Temporal and Spatial Distribution of Leaf Nitrogen Content and Its Relationship with Plant Nitrogen Status in Winter Wheat Diagnosis of N nutrient status of corn using digital image processing technique Tradeoff study on N nutrition status assess approaches of cotton Image analysis method in application of digital image on diagnosing wheat nitrogen status Predicting Wheat Grain Quality with Canopy Reflectance Spectra Research progress on diagnosis of nitrogen nutrition and fertilization recommendation for rice by use chlorophyll meter