Response of the Growth, Photosynthetic Characteristics and As Contents of Panax notoginseng Plant to Soil As Stress

The main objective of this experiment is to make it clear how Panax. notoginseng responses to the soil arsenic(As) contamination and its mechanism. Through field experiment and laboratory analyses, we studied the responses of triennial P. notoginseng growth (morphological index, biomass, photosynthetic characteristics and pigment) to As addition with different concentrations, and the content of As in each parts of plants (stem and leaf, rhizome, main root, fibrous root). Meanwhile, we investigated the effects of As incorporation on P. notoginseng growth, photosynthetic characteristics and As accumulation. The results showed that:(1) P. notoginseng growth was inhibited and biomass decreased significantly under high soil As concentration ( 140 mg/kg), while no significant effects were observed between controls and those with low content of As(80 mg/kg). (2)As addition in high concentration significantly decreased the net photosynthetic rate of leaves (Pn), transpiration rate (Tr), stomatal conductance (Gs) and photosynthetic pigment content, but significantly increased CO2 concentration of cell interval (Ci).(3)The content of As in different parts of triennial P. notoginseng increased with the increase of As addition amount. As content rank in different parts of P. notoginseng was as follows:fibrous root notchmain root stem and leaf. As addition in high concentration significantly inhibited P. notoginseng growth and photosynthesis. The As concentration for P. notoginseng growth smoothly was less than 80 mg/kg.Most of As in P. notoginseng was in the under-ground parts of plants, which should be highly valued.