Morphological and physiological response of hemp to different levels of water availability and salinity

A study was conducted to assess the plant morphological and physiological response of hemp grown under LED light to different levels of water availability and salinity. Chlorophyll, fluorescence, and flavonoids were measured at 15 and 24 days after transplant (DAT). Plants were harvested at 25 DAT, when they were at full flowering stage, and the number of leaves per plant, stem height, and plant fresh weight were measured, and laboratory analysis were carried out for malondialdehyde (MDA), proline, and cannabidiol (CBD) content measurement. Moderate water replenishment (60 % ETc, I60) had negligible effects on morphological traits, whereas a low level of water replenishment (30 % ETc, I30) exerted a significant depressive effect. Salinity negatively affected all morphological traits already at mild level (−0.2 MPa water potential). MDA was higher under moderate (+24 % in I60) and low (+26 % in I30) water replenishment, and picked at 17.4 μmol g−1 FW at the highest level of salinity (−0.4 MPa water potential, +41 %). Proline content was maximized under restricted water conditions (30 % ETc), and at the highest level of salinity (−0.4 MPa). Water limitation significantly increased CBD only at the highest level (30 % ETc, +45.6 % of CBD), whilst salinity induced a strong raise in CBD at both levels (+31.3 and +36.4 % at −0.2 and −0.4 MPa, respectively). Overall, hemp resulted more sensitive to salinity than water scarcity.