三年生三七生长、光合特征及砷含量对土壤砷胁迫的响应

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

为了了解三年生三七对土壤砷污染的响应特征和机理。通过大田种植和室内分析的方法研究三年生三七在不同质量分数砷处理下的生长状况(形态指标、生物量、光合特征、光合色素)以及三七各部分(茎叶、剪口、主根、须根)砷含量,探讨砷处理对三年生三七生长、光合特征及砷积累的影响。结果表明:(1)高质量分数的砷处理(砷质量分数≥140 mg/kg)对三七形态指标、生物量有显著的抑制作用,但低质量分数的砷处理(≤80 mg/kg)对三七生长无显著影响。(2)高质量分数砷处理显著降低了叶片净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)和光合色素含量,显著增加了细胞间隙CO_2质量分数(C_i)。(3)三年生三七各部分砷含量随砷处理质量分数升高而增高,砷含量在三七各部分的分布依次为:须根>剪口>主根>茎叶。高质量分数的砷处理对三七的生长和光合作用具有显著的抑制作用,保证三七正常生长的土壤砷质量分数为80 mg/kg以下,三七中砷的主要分布部位为地下部分,需重点关注。

The main objective of this experiment is to make it clear how Panax. notoginseng re- sponses 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 concen- trations, 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 photosyn- thetic 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 〉 notch 〉 main 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.