Use of soil and vegetation spectroradiometry to investigate cropwater use efficiency of a drip irrigated tomatos

An agronomic research was conducted in Tuscany (Central Italy) to evaluate the effects of an advancedirrigation system on the water use efficiency (WUE) of a tomato crop and to investigate the ability of soiland vegetation spectroradiometry to detect and map WUE. Irrigation was applied following an innovativeapproach based on CropSense system. Soil water content was monitored at four soil depths (10, 20,30 and 50 cm) by a probe. Rainfall during the crop cycle reached 162 mm and irrigation water appliedwith a drip system amounted to 207 mm, distributed with 16 irrigation events. Tomato yield variedfrom 7.10 to 14.4 kg m-2, with a WUE ranging from 19.1 to 38.9 kg m-3. The irrigation system alloweda high yield levels and a low depth of water applied, as compared to seasonal ET crop estimated withHargraves' formula and with the literature data on irrigated tomato. Measurements were carried outon geo-referenced points to gather information on crop (crop yield, eighteen Vegetation indices, leafarea index) and on soil (spectroradiometric and traditional analysis). Eight VIs, out of nineteen onesanalyzed, showed a significant relationship with georeferenced yield data; PVI maps seemed able toreturn the best response, before harvesting, to improve the knowledge of the area of cultivation andirrigation system. CropSense irrigation system reduced seasonal irrigation volumes. Some vegetationindexes were significantly correlated to tomato yield and well identify, a posteriori, crop area with lowWUE; spectroradiometry can be a valuable tool to improve irrigated tomato field management.