Influence of drought stress on the leaf morphology and physiological characteristics in blackberry (Rubus L.) seedlings

In the present study, the physiological changes and morphological characteristics were investigated in the leaves of blackberry ‘Boysenberry’ seedlings subjected to 14-day drought stress by withholding irrigation. The leaf relative water content (RWC), and concentrations of photosynthetic pigments and hydrogen peroxide (H₂O₂) in leaves were analyzed. The results showed that RWC increased slightly at first and then decreased. H₂O₂ content changed slightly in leaves of ‘Boysenberry’ during the experiment period. Drought stress induced significant accumulation of photosynthetic pigments and reached the peak on day 10. Besides, scanning electron microscopy (SEM) revealed a drought-resisting apparent structure in ‘Boysenberry’. Drought stress significantly influenced the stoma on the lower epidermis of the leaves. As compared to the control, higher stomatal density was observed under drought conditions. Besides, there were elongated cone-shaped unicellular trichomes densely distributed on the abaxial surface of the lower epidermis. Overall, these results demonstrated that ‘Boysenberry’ exhibited a certain degree of drought adaption. It was suggested that increased drought tolerance of ‘Boysenberry’ was due to high stomatal and trichomes density, better accumulation of photosynthetic pigments and maintenance of tissue water contents.