Effect of drought stress on morphophysiological and biochemical traits of purple (Cercis siliquastrum L.) seedlings

Purple (Cercis siliquastrum L.) is one of the most important species in landscaping and afforestation. Due to both ecological and economical values, knowledge on the water needs and resistance of purple to different levels of drought stress is essential. Therefore, an experiment in a completely randomized design with four levels of drought stress including field capacity 100% (control), 75% (mild stress), 50% (medium stress) and 25% (severe stress) was performed in greenhouse conditions to study the effect of drought stress on morpho-physiological and biochemical traits of purple seedlings. Results showed that severe drought stress decreased seedling height, leaf area, relative leaf water content (63.3, 77.7 and 62.6%, respectively) and increased electrolyte leakage and malondialdehyde concentration (63.6 and 334.5%, respectively) compared with plants in the control treatment. Drought stress level of 25% of field capacity increased root length by 42.1%. In addition, activity of catalase, peroxidase and ascorbate peroxidase enzymes (862, 553.9 and 349.6%, respectively) increased with increasing drought. The results also showed that only the level of drought stress of 25% of field capacity reduced the survival of seedlings by 55%. Therefore, this species was concluded to be able to withstand water stress up to 75% of field capacity without causing damage, while its growth and yield will be severely affected if the amount of water is reduced to the threshold of 25% of field capacity.