The effects of elevated CO 2 (0.5%) on chloroplasts in the tetraploid black locust ( Robinia pseudoacacia L.)

摘要

Abstract Some ploidy plants demonstrate environmental stress tolerance. Tetraploid (4????) black locust ( Robinia pseudoacacia L.) exhibits less chlorosis in response to high CO 2 than do the corresponding diploid (2????) plants of this species. We investigated the plant growth, anatomy, photosynthetic ability, chlorophyll (chl) fluorescence, and antioxidase activities in 2???? and 4???? black locusts cultivated under high CO 2 (0.5%). Elevated CO 2 (0.5%) induced a global decrease in the contents of total chl, chl a, and chl b in 2???? leaves, while few changes were found in the chl content of 4???? leaves. Analyses of the chl fluorescence intensity, maximum quantum yield of photosystem II (PSII) photochemistry ( Fv/Fm ), K-step ( V k ), and J-step ( V J ) revealed that 0.5% CO 2 had a negative effect on the photosynthetic capacity and growth of the 2???? plants, especially the performance of PSII. In contrast, there was no significant effect of high CO 2 on the growth of the 4???? plants. These analyses indicate that the decreased inhibition of the growth of 4???? plants by high CO 2 (0.5%) may be attributed to an improved photosynthetic capacity, pigment content, and ultrastructure of the chloroplast compared to 2???? plants.