Effects of arsenic on growth, photosynthesis and some antioxidant parameters of Panax notoginseng growing in shaded conditions

Article Type: Full Length Research Article This study assessed the effect of soil Arsenic (As) on growth height, leaf area, biomass, relative growth rate (RGR), photosynthetic activities [net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), inter-cellular CO2 concentration (Ci)] and selected antioxidant parameters [superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)] of Panax notoginseng (Burk.) F. H. Chen. Two-years old plants in part-shade were subjected to As treatments, which were applied by supplementing soil with As to a final concentration of 20, 80, 140, 200 and 260 mg kg -1 with supplementary Na3AsO4•12H2O. The results obtained shows that total biomass, contents of total chlorophyll (Chl), Chl A and Chl B increased at low (20 mg kg -1 ) As concentration; but declined at higher (80-260 mg kg -1 ) As concentrations. The Chl A/B ratio, carotenoid content and ratio of root biomass to shoot biomass decreased in all As treatments. Pn had a 1.40-1.49 fold increase with As concentrations from 0 to 140 mg·kg -1 . Tr, Gs and stomatal limitation value increased significantly, whereas the inter-cellular CO2 concentration and water use efficiency declined under As stress. Leaf SP content, relative electrical conductivity and activities of SOD, CAT and POD increased under As stress. These results indicate that stomatal limitation value should be the most important factor responsible for Pn decline under As stress. The sensitive markers of P. notoginseng under As stress include growth characteristics (leaf area, RGR, biomass) and antioxidant parameters (relative electrical conductivity, SOD activity). ©2016 BluePen Journals Ltd. All rights reserved