| Selenium（Se）is one of the essential trace elements for human body.It has the function of anti-oxidation and maintaining the normal function of human immune system.Se deficiency can seriously affect human health.Se deficiency in soil is common in China.Rice is one of the main food crops in China,and rice is an important food source for Se supplementation for Chinese residents.Therefore,the researches on the distribution,its migration and transformation of Se in the rice-soil system of great significance.In this study,a rice base of 10,000 mu in Yujiawan area of Pukou,Nanjing,located in the Yangtze River Delta region,was selected as the research site,and the soil-rice system was taken as the research objective.Soil and rice plant samples under natural conditions of the base were systematically collected,as well as rice plant samples strengthened by soil Se biofortification.Soil Se content,soil available Se content and rice Se content were analyzed.Kriging interpolation method was used to perform spatial interpolation analysis on the Se content in soil and rice to plot a spatial distribution map of soil Se and rice Se in 10000 mu of functional rice base under natural conditions.Based on the trace Se speciation analysis techniques supported by HPLC-ICP-MS,the total Se and Se speciation and composition in rice plants were systematically analyzed.The accumulation and transformation of Se in various organs of rice plants with and without biofortification were compared.The main research contents and results are shown as follows:（1）The spatial distribution and influencing factors of soil Se in 10000 mu functional rice base in Yujiawan area.According to the analysis of soil Se content in the study area,the results showed that:（a）the total Se content in the soil samples in the study area ranged from 35 to 350μg/kg,with an average value of 200±58μg/kg（n=75）,and the bioavailable Se content in the soil samples ranged from 19.16 to 43.84μg/kg,with an average value of 28.41±4.84μg/kg（n=20）.The bioavailable Se content in the soil accounts for 15.2±2.3%（n=20）of total Se.（b）The spatial distribution is in strips,and its content decreases from southwest to northeast in total soil Se.The Se content of the soil along the Qingliu River is significantly lower than that along the Chu River.In addition,the spatial distribution characteristics of soil bioavailable Se and total Se were similar.（c）There was a significant negative correlation between soil p H and total selenium content（p<0.01）,and the correlation coefficient was-0.471.Significant differences in the contents of total Se and bioavailable Se in soils with different p H values were calculated,which indicates that soil p H was the key controlling factor of soil total Se and bioavailable Se contents.（d）The contents of calcium,potassium,magnesium,molybdenum,vanadium,tin,rubidium,zinc,copper,chromium,nickel,iron,manganese,silicon,boron,iodine and other mineral elements essential for human body in the soil were significantly correlated with the content of total Se in the soil.The results indicate that Se may be associated with some mineral elements needed by human body,such as calcium,potassium and magnesium in the soil.（2）The spatial distribution of rice Se in 10000 mu functional rice base in Yujiawan area.According to the analysis of rice Se content in the study area,the results showed that:（a）The total Se content in the rice samples in the study area was 13～96μg/kg,with an average content of 31±15μg/kg（n=59）.18.64%of the rice samples meets the national Se-Rich rice standard;and the total Se content in Se-Rich rice was 40～96μg/kg with an average content of 53±18μg/kg（n=11）.（b）The spatial distribution of the total Se content of rice is distributed in a blocky belt,which is different from the spatial distribution of total Se and bioavailable Se in soil.The content of rice increased from southwest to northeast,and Se-rich rice was mainly cultivated in northeast area.（c）The bioconcentration factor（BCF）of Se in rice ranged from 4%to 84.62%,with an average value of 17.19±13.10%.The BCF of rice with biofortification is 27.63±12.35%while the BCF of rice without biofortification is 14.64±11.96%.Considering its strong ability of accumulating Se and widespread cultivation,the rice is suitable for Se supplementation in Selenium-deficient areas.（3）A comparative study on accumulation and composition characteristics of Se in rice after selenium biofortification.Based on HPLC-ICP-MS Selenium speciation analysis technology,the characteristics of Se speciation in rice plants were studied,the results showed that:（a）the total Se content of different organs in rice is different,and it decreased from roots to stems,leaves and grains.There are also differences in the transport factor of organs.The transportation of Se from roots to stems is the most difficult,and the transportation from stems to leaves is the easiest.（b）After Se biofortification,Selenium bioconcentration factor in rice root was still significantly higher than that in leaf,stem,rice husk and polished rice,followed by leaf,stem and rice husk,and polished rice.Compared to root,lower Se bioconcentration factors in rice stem,leaf,husk and polished rice suggest that large amounts of Se may be adsorbed on the roots and not transported upward to aboveground tissues.（c）There were differences in the forms of Se in significant different organs of rice at mature stage,among which the proportion of selenomethionine（Se Met）was the highest.The Se Met in stem,leaf and husk of rice was significantly higher than in the control group.Selenium in rice stems and leaves was transported upward and accumulated in grains in the form of SeMet and SeCys2. |
PDF Full Text Request