Screening Of Low-Arsenic Rice Genotypes And Effects Of Silicon On Arsenic Accumulation And Translocation

One of the sources of arsenic(As)taken in by human is contaminated crops.Rice(Oryza sativa L.)is one of the most important staple food for nearly a half of the whole world’s population.Unfortunately,rice is easily to absorb and accumulation As in grain compared with other crops.China is one of the most serious countries polluted by As,excessed As in paddy field resulted in contamination of rice grain in southern China.An effective approach to reduce As tranformation into human from food chain is to decrease As accumulation in rice grain.There are two main metheds to decrease the As concentration of rice grain.one is to screen the low accumulation rice cultivars in As contaminated paddy field,another is to regulate the uptake of As and transformation to grain by application of exogenous material.Silicon is chemical analogue of As(Ⅲ),it can inhibit As uptake by competiting the same transport protein in roots and promote the biomass of rice.To evaluate the genetic variations in As concentrations of rice grains,three field experiments were conducted using 123 rice cultivars in Hunan Province.The results showed that,there were significant differences in As accumulation in rice grains among different rice cultivars.The As concentrations of the highest cultivars were 2.5,3.4 and 1.8 folds of the lowest ones in three experimental sites,respectively.The inorganic As is the main form As in rice grains.The As concentrations in brown rice was positively correlated(p<0.001)with that in straw.There were significant positive correlations between As concentration in brown riceof 3 experimetal sites(p<0.001).The biomasses and grain As concentrations of hybrid rices were significant higher than those of conventional rices in low As-contamination site.BR-3,BHD-7 and BHD-3 are the stable low As accumulating cultivars,and XFY390,YLY888,ZD99 and SD11 are high As accumulating cultivars.Based on the field experiments,high accumulating cultivar ZD99 and low accumulating cultivar BR-3 were selected to study the effect of silicon(Si)on rice grow and As accumulation under As exposure.The results showed that the application of Si increased above-ground biomass of rice seedlings and decreased the As concentration in above-ground of ZD99.The root length,shoot height and fresh weight of above-ground were significant increased by appling Si at maturity stage.Silicon significantly decreased the As concentration in root,leaf and spike at mature stage,and As in stem and spike at filling stage’s of ZD99.The As concentration in root and leaf of BR-3 were also significantly decreased at mature stage.Si supply could also bring down the TF(spike/root),TF(spike/leaf),TF(spike/stem)of ZD99 at mature time,significantly.But there is no significant effect on BR-3’ TF.This study is helpful to decrease the As accumulation in rice grain in agricultural production.