Leaf morphological and physiological responses of Persian oak trees in oak decline affected stands

In order to study morphological and physiological responses of Persian oak trees leaves, one of the dieback affected stands in Melah-Siah region in the northern half of the Ilam province was selected. Oak trees were divided into 4 groups with 6 replicates based on the severity of crown dieback. Leaf samples were randomly taken in South directions of trees crown in spring and summer during two consecutive years and were transferred to the laboratory for analyzing of some morphological and physiological traits including leaf area, wet and dry leaf weight, SLA, LMA and RWC. Results showed that the interaction effect of season and crown dieback degrees on morphological and physiological traits was not significant. But all of the studied traits had significantly ascending or descending temporal variations. Results showed that the dry leaf weight of dieback trees in spring 2014 was more than that of healthy trees. The leaf area of dieback trees in spring 2013 and in spring and summer 2014 was less than those of healthy trees. The amount of leaf water of dieback trees in spring and summer 2013 was less than that of healthy trees. The leaf moisture weight of dieback trees in spring and summer 2013 and spring 2014 was less than that of healthy trees. The RWC amount of dieback trees in spring and summer 2013 and spring 2014 was less than those of healthy trees. It was concluded that drought has more severe impact on the morphological and physiological status of Persian oak dieback trees leaves and responses of some traits in the dieback trees is for resistance to drought condition and possibly performance of vital activities.