Detection of salinity stress in soilless tomato based on crop reflectance

Salinity is one of the most serious abiotic factors limiting the productivity of agricultural crops, with adverse effects on germination, plant water relation and crop yield. Until recently, salinity stress management techniques were based on electric conductivity measurements that indicate the salinity level in the root zone or destructive sampling methods, something difficult to realise in real time. Hyperspectral sensing is a non-destructive sensing technology that can be used to extract information from a target object based on spectral data. In the present work, the effect of salinity level on leaf reflectance measured by a portable hyperspectral sensor (ASD Inc.) is studied. For this purpose tomato plants were cultivated under two levels of salinity (electrical conductivity: 2.7 and 5 dS m^‑1). Plant spectral data were transformed into vegetation indices to define the physiological status of the crop. The results of the study are promising and show that hyperspectral sensors could be used for early salinity stress detection.