A methodological approach for defining spectral indices for assessing tomato nitrogen status and yield

Efficient use of fertilizers is a main goal that research in agriculture shall address. Dynamic fertilization management is a way of bringing nutrients to the plant when they are crucial for its development. However, destructive measurements of crop nitrogen status are still too costly and time consuming to justify their use, and the implementation of methodologies based upon non-destructive, quick and easy to use tools for plant nutritional status monitoring appears as an appealing opportunity. In this paper vegetation indices based on crop reflectance through the use of a multispectral radiometer (MSR-87, Cropscan Inc.) are compared. Results from three years of experimentation are provided in order to evaluate (a) relations existing between several vegetation indices and both leaf chlorophyll and nitrogen content; (b) the ability of the tool to respond to different nutrient supply and/or (c) to predict yield. A methodological approach for the definition of the most reliable index is proposed and the adopted procedure allows to define the NIR/R560, even with some degrees of incertitude, as the most suitable index for the evaluation of tomato crop nutritional status.

► In this paper vegetation indices based on crop reflectance are compared.
► Results from three years of experimentation are provided.
► The paper assess relations with chlorophyll and N content, N supply and yield.
► A methodological approach for the definition of the most reliable index is proposed.
► NIR/R560 appears as a reliable tool for the evaluation of tomato crop N status.