Diagnosis of nitrogen nutrition in winter wheat (Triticum aestivum) via SPAD-502 and GreenSeeker

Leaf SPAD and canopy NDVI of winter wheat under different nitrogen treatments were analyzed using GreenSeeker and SPAD-502 with the aim of building a quick, timely and accurate method for diagnosing nitrogen nutrition. The results show significant positive correlations among leaf SPAD, canopy NDVI and chlorophyll content. Correlation coefficients for leaf SPAD and leaf N and chlorophyll content are significant, except during heading and reviving stages. Correlations for canopy NDVI with leaf N and chlorophyll content at jointing and milking stages are similar to that for leaf SPAD. While SPAD can be used to evaluate chlorophyll content, NDVI can be used to assess nitrogen content. The recommended period for diagnosing nitrogen status is jointing stage. Using SPAD and NDVI, a linear regression model is developed for assessing yield of winter wheat.