Genotypic Difference In Arsenic-Accumulating Ability And Their Reaction To Environmental Factors In Pteris Vittata

Phytoremediation is a special technoloque of remediating contaminated soil by using the plant hyperaccumulators to remove pollutants in soil. The hyperaccumulators has the great capacity of absorbing heavy metals from soil and transporting most of them into the above-ground parts, which are then harvested artificially and dealt with properly, making a dramatic reduction of heavy metal content in soil. It is commonly recognized that phytoremediation is a cost-effective, engineering-economical and environmental friendly technique, and shows great prospect in the practice of contaminated soil remediation.Pteris vittata is a newly discovered As-hyperaccumulator, and has been identified as a reasonable material for use in phytoremediation of As-contaminated soil. There are abundant germplasm of Pteris vittata in China It is shown in the field investigations that there exists a large variation in morphology and growth characterizations, and As-acumulating ability among Pteris vittata genotypes, inhabited in the different ecological zone of China. It is also demonstrated in the field trials that some exotic substance have substantial influence on As uptaking by Pteris vittata, indicating the significance of applying proper chemicals into the soil to be remidiated in improving remediation efficiency. However, little research has been done in study on the genotypic difference of Pteris vittata in As-accumulating ability.In a survey aiming at making clear of the environmental conditions of plants in the As-contaminated areas in Hunan Province, it is found that As-contamination has caused a marked decrease in plant species and reduction in biomass of the plants grown there. Moreever, there is higher than 54% of cultivated vegetables with As content beyond the critical value of safety for food. Of them, spinach, crown daisy and lettuce are particularly severe in terms of their As content, being 5 fold as high as Maximum Permitted Concentration (MPC) based on Chinese Stardard of Vegetable Sanitation. It may be concluded that As-contamination in the soils of these areas has posed the great threat to human health.The direct seeding experiments of different Pteris vittata genotypes showed that there was significant difference in germination and emergence traits among Pteris vittata genotypes collected from different areas in China, with germinating time ranging from 12-40days, duration from germination to emergence varying between 13-46 days. As the seeds of Pteris vittata are very small, with little stored nutrition, the genotypes, which are quick in germination and emergence, are suitable for direct seeding in the field. According to the results, 6 genotypes, coded as No. 3, 4, 5, 9, 13 and 15, are scrrened out for their more probability in success of directly seeding in field.The growth traits, As-tolerance and bioaccumulation of different Pteris vittata genotypes, which were collected from different areas of China, were studied. The result showed that there was a remarkable difference in plant height, number of frond and sprout, fresh weight of above-ground parts and roots among different genotypes. Plant height varied from 29.6 to 68.2 cm, frond from 13.3 to 60.0 per plant and sprout from 9.0 to 65.7 per plant, fresh weight of aboveground parts and soil ranged from 150 to 540 g and from 20.3 to 94.9 g per plant, respectively. Meanwhile, the significant difference was also noted in As concentration and accumulation in plants among Pteris vittata genotypes. The As concentration in aboveground parts and roots ranged from 643.1 to 3009.03 mg/kg, and from 44.4 to 112.4 mg/kg, respectively. Correspondingly, As accumulation in aboveground and roots ranged from 49.7 to 174.7 mg per plant and from 0.48 to 2.84 mg per plant, respectively. Bioaccumulation factors (BF) varied from 17.2-81.9 and transport factors (TF) from 10.8-50.4. The wide difference in biological traits and As-accumulating ability among Pteris vittata genotypes illuminated that it is possible to develop the Pteris vittata genotypes with higher As-bio...