The altitudinal effects on photosynthesis of Rosa platyacantha from the Tianshan Mountains in Northwestern China

The altitudinal effects on photosynthesis were measured on progenies of three populations of Rosa platyacantha Schrenk from altitudes of 1,170 (L); 1,580 (M); and 1,920 (H) m a. s. l. During the day, net photosynthetic rate (P (N)) decreased in all populations due to the high air temperature in the summer. The H population showed a significantly lower P (N) at noon compared to other populations. The midday depression of P (N) occurred in L and M populations due to stomatal limitations, while P (N) inhibition was associated with PSII activity decline in the H population. In order to avoid photodamage, the plants of H population triggered active antioxidant defenses with a higher enzyme activity and redox ratio of ascorbate at midday compared to the L and M populations. However, more oxidative injury still occurred in the H plants at noon due to higher lipid peroxidation. Our results indicated that the provenance significantly affected photosynthesis in R. platyacantha from northwestern China.