Morpho-physiological responses of Lycium ruthenicum Murr. propagated by tissue culture to drought stress

To estimate the drought tolerance of Lycium ruthenicum Murr., which is propagated through tissue culture, we conducted a laboratory experiment to investigate the morphological and physiological responses of this species under various levels of drought stress (10%, 20%, and 40% polyethylene glycol (PEG)). The results showed that leaf morphology (leaf length, area, thickness, aspect), actual water content (AW), water deficit (WD), relative water content (RWC), absolute water content (AWC), chlorophyll fluorescence parameters, such as Fv/ Fm and maximum quantum yield (QY) and fluorescence decrease ratio (Rfd), were affected in L. ruthenicum transplanted from in vitro to ex vitro conditions. In plants treated with 10% PEG, the leaf length and leaf area are increased. Also, the leaf thickness, water exchange, and chlorophyll fluorescence parameters also remained comparable to those of control plants, indicating that L. ruthenicum treated with 10% PEG maintained normal physiological activity. Plants treated with 20% and 40% PEG exhibited a reduction of the leaf length and leaf area. In L. ruthenicum treated with 20% PEG, the Fv/Fm and Rfd values decreased to 0.61±0.04 and 1.61±0.25, respectively, resulting in reduced photosynthetic activity, although plant survival remained viable. Conversely, in L. ruthenicum treated with 40% PEG, the Fv/Fm and Rfd values decreased to 0.33±0.05 and 0.49±0.12, respectively, causing in a significant reduction in photosynthesis and plant survival. Even after normal watering, L. ruthenicum demonstrated an inability to recover from 40% PEG treatment, indicating that it cannot tolerate this level of drought stress.