The Effects Of Soil Mercury On Physiological And Biochemical Characteristics Of Helianthus Tuberosus L.

Mercury is the only liquid metal element at normal temperature and pressure, and the toxicity of mercury and its compounds are very strong. With the development of economy, more and more mercury has been used, and the environmental pollution has attracted much attention. Soil as the important part of environmental elements; is easy to cause serious impact to pant growth. With the increase of soil mercury content, but so far there is no mercury hyperaccumulation plant species found. Jerusalem artichoke (Helianthus tuberosus L.) is a good nonfood bioenergy plant species with strong stress resistance, huge biomass and suitable for cultivation in marginal land. Jerusalem artichoke lines with tolerance mercury are screened not only to be used to mercury pollution of soil restoration but also to get huge economic benefits. Within the groups derived from the genetic data, both morphological and chemical traits, we get three groups:Group Ⅰ higher tuber yield and total sugar content.; Group Ⅱ longer vegetative growth; Group Ⅲ higher nutrient content, stronger sexual reproduction and resistance stress ability, we selected LZJ047, LZJ119 and LZJ033 in three groups as experimental materials respectively. We had studied the effects of soil mercury on growth, physiological and biochemical characteristics, photosynthetic fluorescence and accumulation of mercury properties at plant germplasm repository of Lanzhou university during 2013-2014. The results as follows:(1) Jerusalem artichoke was severely growth stunted under mercury stress. The seedling germination was delayed, and serious inhibiting growth of Jerusalem artichoke under higher mercury concentration, the mortality of LZJ047 reached to 86.19% at 10 mg kg-1 of mercury concentration. The plant height, internode length, leaf number and leaf area were significantly decreased of different lines under higher mercury concentration. The total biomass of different lines was decreased with the increase of mercury concentration, the reduction of total biomass at 10 mg kg-1 was LZJ047>LZJ033>LZJ119. The tuber and root biomass of LZJ047 and LZJ033 was significantly declined at 1 mg kg-1, but the LZJ119 was 5 mg kg-1. The change of leaf and stem biomass was slow and the LZJ033 was not affected by mercury stress.(2) The adversity physiological indexes was significantly affected by mercury siress, the MDA, proline and soluble sugar content was significantly increased in all lines under higher mercury concentration, and compared with LZJ047 and LZJ033,the LZJ119 was changed slowly. The ascorbic acid, soluble protein content and the activity of SOD POD and CAT was increased and then decreased under mercury stress in all lines, in all LZJ 119 and LZJ033 was better(3) The chlorophyll content of Jerusalem artichoke was decreased with mercury concentration increase, and the photosynthetic rate was significantly decreased at higher mercury concentration, and the largest decline was LZJ047 reached to 45.14%, the smallest decline was LZJ119 reached to 22.75%, simultaneously the stomatal conductance and transpiration rate were decreased, intercellular CO2 concentration of LZJ047 was increased but LZJ119 and LZJO33 was decreased, and the stomatal limitation appeared opposite change, the water use efficience was significantly decreased. The light response curve was mainly affected by mercury stress compared with CO2 response curve. With the mercury concentration increase, the Fo increase, Fm, Fv, Fv/Fm, Fv/F0 and ETR decrease but cpPS Ⅱ was significantly decreased in 10 mg kg-1only LZJ047.(4) With the mercury concentration increase, root mercury content was biggest increase in all organs, and the highest content reached to 1269 μg g-1 in 10 mg kg-1 of LZJ033 and 156.76 times higher than control. The mercury content of leaf stem and tuber was low, and the highest content of mercury was 57.83 μg g-1,32.36 μg g-1 and 39.5 μg g-1 in 10 mg kg-1 of LZJ033, and significantly less than root mercury content.On the whole, the lines had different characteristics of sensitivity, resistance and enrichment from different groups to mercury. The lines of LZJ119 had the good property of tolerance of mercury stress, LZJ033 had the good characteristic of mercury enrichment, and LZJ047 was most sensitive to mercury stress. LZJ119 and LZJ033 were suitable for cultivation in the low concentration of mercury contaminated soil and applied to restoration mercury pollution of soil.