Method for measuring the water content of a leaf by means of terahertz waves, which comprises subjecting a leaf (LS) to terahertz radiation, detecting the transmitted terahertz radiatio (TTB) through the leaf (LS), determining the water content of the leaf from the transmitted terahertz radiation (TTB) detected. The method further comprises the determination of the total projective area (A) of the leaf. The determination of the water content of the leaf (LS) includes the determination of the optical density (T) of the leaf starting from the transmitted terahertz radiation (TTB) detected, the determination of the product of the optical density (T) with the total projective area (A) of the leaf, and the determination of the absolute water content (Mw) of the leaf by comparing the product with a calibration curve which associates the data of the water content with the product data of the optical density with the projective area of leaves of the same variety. Application number: IT 102016000106179; EP 3312590A1
