Effect of Air Pollution Stress on Proline, Carbohydrates and Photosynthetic Pigments in Box Elder (Acer negundo), Case Study: Urmia, Iran

Air pollution could affect growth and quality of the urban landscape trees in addition to residents' health. Planting of tolerant plants have significant influence on improvement of the urban air quality and can reduce harmful environmental pollutants damages. This study aimed to evaluate the effect of air pollution on plant chemical factors in box elder (Acer negundo) in Urmia. The study consists of five different gardens with different degrees of air pollution. Almost five even age plants in each garden were samples. Leaf samples from each tree of outer branches and in low, middle and high height of crown sections were collected. Then carbohydrates, proline, the main and secondary pigments contents were measured. Morphological parameters such as diameter at breast height, height and crown diameter in order to define correlation with chemical factors were recorded. Also their relationship with the level of air pollutants was investigated. The results indicated that carbohydrates and proline amounts of box elder species have a significant difference among studied areas and have been increased with air pollution degree. While pigment contents was lower in polluted region compared to control. No significant correlation between plant chemical and morphological parameters on one hand and significant correlation between plant chemical factors and air pollutants indicates that only pollutants have an effect on plant chemistry characteristics and dimension of box elder trees not effective. Based on the results, box elder can be a resistant species in urban green space because of carbohydrates and proline storage in polluted area.