Ali Parvizi - Department of Biology, Ilam University, Ilam, Iran
Ali Asghar Hatamnia - Department of Biology, Ilam University, Ilam, Iran
Nayer Mohammadkhani - Shahid Bakeri High Education Center of Miandoab, Urmia University, Urmia, Iran
Hamid Reza Naji - Department of Forest Sciences, Ilam Universit, Ilam, Iran

Amygdalus haussknechtii L. belong of the Rosaceae family that is distributed in large areas of Iran. In natural ecosystems, various factors such as altitude level affected the plants photosynthesis. Therefore, the aim of this study was to investigate the effect of altitude level on photosynthesis and chlorophyll pigments in A. haussknechtii L. Photosynthesis parameters (net photosynthesis and transpiration) were measured using a portable photosynthesis device from A. haussknechtii L. at three different altitude level of Qalajeh mountain in Ilam province. Also, content of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids were also measured. The results shown that with increasing altitude, the rate of net photosynthesis and transpiration decreased. Also, the content of chlorophyll a, chlorophyll b and total chlorophyll pigments decreased with increasing altitude. There are a significant positive correlation (p<۱) was observed between photosynthetic parameters (net photosynthesis and transpiration) and chlorophyll a, chlorophyll b and total chlorophyll pigments. However, unlike other photosynthetic pigments with increasing altitude the content of carotenoids has increased, which is actually a response to environmental stress. In general, increasing the altitude causes environmental stresses of the plants condition, including low temperature and soil drying, which resulting rate of photosynthesis and plant growth has decreased.

Net Photosynthesis, Transpiration, Carotenoids, Stress