Effect of Drought Stress on Morphological Characteristics of Tehran Pine (Pinus eldarica Medw.) and Chinaberry (Melia azedarach L.) at Various Ages

Drought significantly affects plant growth and causes delays in growth, and disturbance in physiology. This study aims to investigate the effect of drought stress on the morphological characteristics of Tehran pine and Chinaberry. This study was done factorially with the factor of different ages of tree species and different drought stresses in the form of a randomized complete block design with 10 replications. Collar diameter, height and canopy size were recorded as the average of the zero state of the studied seedlings and the evaluated parameters were measured at the beginning and end of the study period. With the increase of drought stress and decrease of humidity at a certain age, the growth amount of each of the studied factors, including collar diameter, height and crown area decreases. The results showed that the collar diameter, height and canopy surface in 0.3 drought stress compared to 0.5 and 0.7 drought stress at 1, 3 and 5 years old have the highest value. The average comparison results showed that water stress on seedlings is not significant in all cases. Water deficiency has a significant effect on the collar diameter and canopy surface in Tehran pine and on the collar diameter and height of bitter olive. The mutual effect of seedling age and drought stress on the crown area of Tehran pine and collar diameter and height of bitter olive has a significant effect. It is better to use drought stress of 0.7 so that the seedlings used can withstand adverse environmental conditions.