Threshold values of canopy reflectance indices and chlorophyll meter readings for optimal nitrogen nutrition of tomato

Sustainable and optimal economic N management requires correct and timely on-farm assessment of crop N status to detect N deficiency or excess. Optical sensors are promising tools to assess crop N status throughout a crop or at critical times. The ability of optical sensor measurements of canopy reflectance (Crop Circle ACS 470) and leaf chlorophyll (SPAD 502 chlorophyll meter) to assess crop N status was evaluated weekly throughout an...