| The problem of arsenic content exceeded in agriculture food caused by soil arsenic contamination has been concerned by the widespread society,which is being an urgent environmental.problem in the current society.Breeding low-arsenic crops could effectively decrease the influx of arsenic to the human food chain which is an ecofriendly and high maneuverability method.However,the methods of screening the low-arsenic crops need to be innovative and the work efficiency also requires improvement.Therefore,it is significant to establish a low-arsenic crops screening method system and to accelerate the application of arsenic-low crops.This study employed five varieties of lettuce and amaranth species as the research object.We take pot experiment as the base method for screening low-arsenic crops varieties,compared the differences of vegetative period hydroponics,whole growth perid hydroponics,short-term absorption method and pot experiment in screening results.In addition,further study was developed to understand the relationship between arsenic and phosphorus accumulation.According to the result of this study,we hope for providing a more accurate and efficient selection method for low-arsenic crops.The main research results are as follows:1.In the vegetative period hydroponic expetiment,the average As concentration in the aboveground part of five lettuce species were 12.3 and 23.9 mg·kg-1.respectively,when the As concentration in the nutrient solution was 2 and 4 mg·L-1.The average As concentration in the aboveground part of five amaranth species were 2.6 and 6.8 mg·kg-1 in the same conditions.Results of one-way ANOVA for the variations of lettuce and amaranth aboveground As concentrations in vegetative period and whole growth period showed no difference.The aboveground As concentration can keep unchanged after the vegetative period.The low-As species were ziluoma lettuce and yanxuan amaranth.2.A pot experiment was conducted on five lettuce and amaranth cultivars respectively under two soil As levels(L:58.4mg·kg-1,H:130.6 mg·kg-1),it can be found that all species seemed to be healthy and no any visible symptoms of toxicity at two As concentrations used.However,the significant differences were obvious on the root growth of lettuce and amaranth.The average As concentrations in the aboveground part of five lettuce species were 0.64 and 1.28 mg·kg-1 under S1 and S2 soil arsenic levels respectively with this figure were higher than that of As concentrations of amaranth with the average value of 0.37 and 1.15 mg·kg-1 respectively.The amount of As accumulation in shoot of five lettuce species was ranked from high to low in the following order lvluo lettuce?naichoutai lettuce>meiguodasusheng lettuce>luoshal.v lettuce>ziluoma lettuce,amaranth washuahongliuye amaranth?hongliuye amaranth>baiyuanye amaranth>huahong amaranth>yanxuan amaranth.3.In short-time absorption test,when the As concentration in the nutrient solution was 2 and 4mg·L-1,the average As concentrations in the aboveground of five lettuce species were 1.5 and 2.6mg·kg-1.The average As concentrations of amaranth were 1.0 and 2.0 mg·kg-1 respectively.The As concentrations in aboveground of five lettuce species was ranked from high to low in the following order naichoutai lettuce>lvluo lettuce>meiguodasusheng lettuce>luoshalv lettuce>ziluoma lettuce,amaranth was hongliuye amaranth>baiyuanye amaranth>huahongliuye amaranth>huahong amaranth>yanxuan amaranth.This result was basically identical.with the pot experiment and the vegetative period or whole growth perid hydroponic experiment.4.The results revealed that the amount of phosphorus in aboveground of lettuce correlated well?r=0.944?with the amount of arsenic in shoot when the concentration of arsenic in the nutrient solution was 4 mg·L-1.The correlation coefficient between phosphorus in seed and arsenic in shoot of amaranth was statistical.ly significant?r=0.937,0.971?.The correlation between phosphorus in lettuce seed and arsenic in shoot of lettuce was not statistical.ly significant.Only when the As concentration was 2 mg·L-1,the amount of phosphorus in shoot of lettuce correlated well with the amount of arsenic in shoot.The short-time uptake method has the advantages of less time consumption and less pollution,so it can be used as the priority selection followed by the vegetative period absorption hydroponic.Because of slowest and most pollution,the whole growth perid hydroponic is not recommended.In addition,because of phosphorus and arsenic content had positive correlation,it is available to do some pre-screening work by judging the content of phosphorus in plants.further more work needs to be done to provide evidence of this method. |
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