Two grape cultivars, Rish-Baba and Sahebi were subjected to different levels of salinity and some physiological characteristic including the rate of photosynthesis, stomatal conductivity, under-stomatal carbon dioxide and transpiration determined under 0 (control), 25, 50, 75, 100, 125 and 150 mM NaCl levels. One-year old rooted cuttings were cultivated in pots containing perlite and fed with Hoagland nutrient solution. By increasing salinity stress, the rate of photosynthesis, stomatal conductivity and transpiration was decreased. The rate of sub-stomatal carbon dioxide decreased at the beginning of salt stress but increased later, which was primarily related to decreasing stomatal conductivity and later increase was associated with lack of consuming CO2 in photosynthesis process. Based on these results, Rish-Baba cultivar was more tolerant to salinity stress.
