حورا مومنی

This study was conducted to investigate the devastating impact of Mistletoe (Viscum album L.) on asymmetry index and leaf characteristics of Ironwood (Parrotia persicaDC.) in Tamishan Forest, Noor, Iran. For this purpose, 20 Ironwood trees were selected inside and outside of the forest. The results showed that the highest and lowest values of leaf area and specific leaf area were observed in healthy and infected trees, respectively, both inside and outside of the forest. Stomatal characteristics of diameter, area and density also varied depending on location of trees and branch types (healthy or infected). Analysis of variance (ANOVA) indicated that the effect of left or right sides of leaves (sides) and trees were significant, while the interaction between side×trees was not significant. The difference between left and right sides of leaves were also significantly affected by location of trees and branches types. Generally, this study showed that the presence of mistletoe influenced the asymmetry index and have been caused to changes in the morphology of the infected trees. Finally, due to nutrition importance of Viscum album for animal to prevent from death of host trees, mechanical removing of Viscum album from host trees with high density is recommended.

This investigation was conducted to compare the photosynthetic indices in ironwood trees infected by Viscum album L. and healthy trees located both in stand and out of stand in plain forest of Tamishan، Nour city. In each position، five healthy and five infected trees were selected and photosynthetic parameters، stomatal conductance، transpiration and internal CO2 were examined. Results showed that the amount of photosynthesis and stomatal conductance in healthy and infected branches were varied depending on the position of trees، individual trees and branch type. The amount of transpiration and internal CO2 were significantly different in healthy and infected branches. The highest amount of photosynthesis، stomatal conductance، transpiration and internal CO2 both within and out of stand، were measured in healthy trees (except for stomatal conductance in out of stand). Both within and out of stand، healthy branch of infected tree indicates higher level of photosynthetic activity compared with infected branch. Also، twofold comparison of the four parameters investigated showed that photosynthesis، stomatal conductance، transpiration and internal CO2 in healthy branches within stand were higher than those out of stand. It was also discovered that Viscum album caused disruption in photosynthetic activities of the host plant that، is why conducting supplementary studies in this regard is suggested to future researchers.