Water status evaluation of grapevine leaf by means of NIR spectroscopy for a better irrigation scheduling

Crops quality depends on controlled factors as the irrigation timing and/or the amount of water applied, and uncontrolled ones as the environmental conditions and/or the differential phenological sensitivity of fruit to cultural practices. This results in a need of rapid water status monitoring systems in order to better manage crop and irrigation scheduling for a high water use efficiency. Non-destructive methods are a potential solution, replacing the tedious conventional techniques which are time consuming and not easily to perform water status directly in field. The objective was to test the potential effectiveness of a NIR spectrophotometer for a rapid and non-destructive evaluation of the water status of grapevine leaves. Moreover, a variable selection was proposed to determine a set of candidate variables for the prediction of water potential (Ψ; MPa) related to leaf water status in a view of a simplified optical device. The statistics of the PLS models showed in validation R2 ranged from 0.77-0.85. Regarding the wavelengths selection, acceptable MLR models were obtained using fourteen effective variables (R2 ranged 0.63-0.69). The wavelengths selection could be useful for the design of a simplified handheld device in a view of a foreseeable application for real time leaves measurement capable to support small-scale growers in determining water status to optimize the irrigation scheduling.