Selenium Content In Dipsacus Asperoides In Enshi And Its Correlations To Soil Agrochemical Characters

In order to understand the selenium accumulation features of Dipsacus asperoides and the affecting factors of its selenium content,a wild survey in Enshi area and a pot experiment cultivating Dipsacus asperoides by applying selenium in soil was conducted.The selenium contents in samples of Dipsacus asperoides and soils from wild survey and in seedling samples of Dipsacus asperoides from pot experiment were measured by hydride atomic fluorescence spectrometric method,while the soil agromichemical characters was determined by normal methods.The range of selenium content in the roots,stems,leaves and flowers of Dipsacus asperoides from enshi area was 0.029-94.87,0.008-39.45,0.04-123.14 and0.026-143.94 mg/kg,respectively,and the selenium content in soil grown Dipsacus asperoides ranged from 0.5 to 227.3mg/kg.The selenium contents both in Dipsacus asperoides and in soil are the highest in Yutangba selenium mine spot,Shuanghe town,Enshi city,and the lowest in Qincaiping country,Yanzi town,Jianshi county.The selenium contents in all samples of different parts of Dipsacus asperoides from enshi area were the lowest in stems,but 50% of sample's selenium contents were the highest in leaves,37.5% were the highest in flowers,and only 12.5% were the highest in roots.The correlation analysis showed that the selenium contents in the roots,stems,leaves and flowers of Dipsacus asperoides were significant linearly correalted to the selenium contents in soil(P<0.01),and the all correlative coefficients were higher than 0.999.The biological accumulation factors(BAF)of Dipsacus asperoides from Enshi to soil selenium ranged from 0.012 to 0.727,and were also the lowest in stems.The relationship between BAFs and soil selenium contents was only significant in leaves,but not significant in other parts.The pot experiment of soil selenium applications indicated that the seleniumcontents in the seedlings of Dipsacus asperoides ranged from 0.18 to 10.67 mg/kg in thinning seedlings,and from 0.27 to 10.94 mg/kg in planting seedlings.Both thinning and planting seedlings,their selenium contents were significantly correlative to soil selenium applications and their BAFs to soil selenium ranged from 0.3 to 0.9,but it had an insignificantly negative correlation to soil selenium applications.The correlation analysis of selenium content in Dipsacus asperoides to soil agrochemical characters showed that the selenium contents in the roots,stems,leaves and flowers of Dipsacus asperoides had the significant correlations to the contents of soil organic matter(P<0.01),available phosphorus(P<0.01),total phosphorus(P<0.01)and nitrate(P<0.05),but not significant to alkali-hydrolyzable nitrogen,total nitrogen,available potassium content and pH.The results from the correlation analysis of soil selenium content to soil agrochemical characters of the samples from Enshi area exhibited that the soil selenium content had the significant correlations to the content of soil organic matter(P<0.01),available phosphorus(P<0.01),total phosphorus(P<0.01)and nitrate(P<0.05),but insignificant to alkali-hydrolyzable nitrogen,total nitrogen,available potassium content and pH.In summary,the wild Dipsacus asperoides from Enshi area had the strong ability to accumulation of soil selenium,and thus it is feasible to develop the selenium-enriching Dipsacus asperoides in natural selenium enriched soil and in selenium application soil.Besides the soil selenium content,the content of soil organic matter,available phosphorus,total phosphorus and nitrate are the factors that affected the selenium contents in Dipsacus asperoides,while the soil parent materials,organic matter and phosphorus maybe the important affecting factors of soil selenium content in Enshi area.