| With the increasing heavy metal pollution in farmlandWith,the repair of heavy metal soil pollution in farmland and food safety issues have received widespread attention.There are various techniques for remediation of farmland soil contaminated by heavy metals,but at present there is no complete technical system that can be effectively used for heavy metal pollution in large areas.The screening of crops with low accumulation of heavy metals is a very economical repair method.The differences in the absorption of heavy metals among different varieties of the same crop are very obvious.For medium and light heavy metal contaminated farmland that occupy a large area of pollution,you can pass Selection of low-absorption crop varieties to achieve the safe production of food crops.At present,there are many researches on the selection of low-absorption rice varieties for acidic heavy metal-contaminated soils in the south,and heavy metal pollution in agricultural fields in the arid and semi-arid agricultural production areas of the North China Plain has gradually presented multi-source,complex,large-scale,extensive and persistent severe In light of the situation,there are relatively few studies on winter wheat and summer maize varieties with low heavy metal absorption.Therefore,this study focuses on the migration and transformation characteristics of heavy metals in farmland polluted by medium and light heavy metals through field trials,to study the differences in the absorption of heavy metal cadmium by different varieties of winter wheat and summer maize,and to select low-absorption varieties for the North China Plain Provide theoretical basis for the safe production of food crops in arid and semi-arid agricultural production areas.Based on the planting structure of the North China Plain,the differences in the absorption of heavy metal cadmium by 47 different varieties of winter wheat and 46 different varieties of summer maize were studied,and winter wheat and summer maize varieties with low accumulation of cadmium were selected.(1)The content of heavy metal cadmium in different parts of winter wheat was root>stem>seed.And the transfer coefficient and bioconcentration coefficient of cadmium were less than 1,the former ranged from 0.10 to 0.60,and the later ranged from 0.002 to 0.06.The content of heavy metals in winter wheat seeds of different varieties ranged from 0.004 ~ 0.13,with a difference of 35.28 times.And 42 species with cadmium content in seeds were selected in accordance with national standard GB2715-2016?0.10 mg/kg,accounting for 89.36% of all varieties,and there were 5 species exceeded the national standard.Cadmium absorption of winter wheat showed great difference among different varieties.(2)The content of heavy metal cadmium in different parts of summer maize was root>stem>seed.And the transfer coefficient and bioconcentration coefficient of cadmium were less than 1,the former ranged from 0.21 to 0.95,and the later ranged from 0.009 to 0.58.The content of heavy metals in summer maize seeds of different varieties ranged from 0 ~ 0.14.And45 species with cadmium content in seeds were selected in accordance with national standard GB2715-2016?0.10 mg/kg.Cadmium absorption of summer maize showed great difference among different varieties.(3)There was a difference in the absorption of cadmium by different winter wheat varieties.Total length,total surface area,total volume,and total tip number of roots all decreased with the increase of cadmium concentration in the nutrient solution.The addition of Si could effectively alleviate cadmium toxicity and promote root growth compared to other exogenous substances.With 10 mg·L-1 of Cd,compared with CK,the highest increases due to Si addition in root total length,total surface area,total volume,and total tip number in Bainong 418 were 79.43%,75.31%,76.09%,and 75.74% respectively.Concomitantly,Si reduced the cadmium content in roots and shoots in different winter wheat varieties with the highest reductions of 87.59% and 88.18% respectively in Bainong 418. |
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