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Journal of Zhejiang University SCIENCE B

ISSN 1673-1581(Print), 1862-1783(Online), Monthly

Variations in cadmium and nitrate co-accumulation among water spinach genotypes and implications for screening safe genotypes for human consumption

Abstract: Vegetables are important constituents of the human diet. Heavy metals and nitrate are among the major contaminants of vegetables. Consumption of vegetables and fruits with accumulated heavy metals and nitrate has the potential to damage different body organs leading to unwanted effects. Breeding vegetables with low heavy metal and nitrate contaminants is a cost-effective approach. We investigated 38 water spinach genotypes for low Cd and nitrate co-accumulation. Four genotypes, i.e. JXDY, GZQL, XGDB, and B888, were found to have low co-accumulation of Cd (<0.71 mg/kg dry weight) and nitrate (<3100 mg/kg fresh weight) in the edible parts when grown in soils with moderate contamination of both Cd (1.10 mg/kg) and nitrate (235.2 mg/kg). These genotypes should be appropriate with minimized risk to humans who consume them. The Cd levels in the edible parts of water spinach were positively correlated with the concentration of Pb or Zn, but Cd, Pb, or Zn was negatively correlated with P concentration. These results indicate that these three heavy metals may be absorbed into the plant in similar proportions or in combination, minimizing the influx to aerial parts. Increasing P fertilizer application rates appears to prevent heavy metal and nitrate translocation to shoot tissues and the edible parts of water spinach on co-contaminated soils.

Key words: Genotypic difference; Heavy metal; Nitrate; Soil pollution; Water spinach

Chinese Summary  <20> 基于筛选安全的共低积累基因型评价空心菜对镉和硝酸盐积累的变异

目的:筛选镉-硝酸盐共低积累空心菜基因型,并研究降低空心菜重金属含量,提高营养品质的农艺措施.
创新点:首次筛选得到镉-硝酸盐共低积累空心菜基因型,并研究空心菜可食部污染物、矿质元素和营养指标之间的相关性,提出进一步降低空心菜可食部镉和硝酸盐含量的农艺措施.
方法:共38个空心菜基因型收集于世界各地,种植在连作了7年的中度镉-硝酸盐复合污染土壤上(Cd 1.10 mg/kg,NO3 235.2 mg/kg),4周后收获.用HNO3-HClO4(体积比5:1)消煮,电感耦合等离子体质谱仪(ICP-MS)测定各种金属元素,水杨酸-硫酸比色法测定硝酸盐含量,钒钼黄比色法测定磷含量,2,6-二氯靛酚滴定法测定维生素C含量,乙醇-丙酮(体积比2:1)比色法测定叶绿素含量.
结论:本试验筛选得到镉-硝酸盐共低积累空心菜基因型4个(Cd <0.71 mg/kg DW,NO3 <3100 mg/kg FW),分别是JXDYGZQLXGDBB888,可以在中轻度镉-硝酸盐复合污染土壤上安全生产.空心菜地上部镉与铅、锌含量呈正相关,而这3种元素均与磷量呈负相关.这些结果表明镉、铅和锌通过相同的途径被空心菜吸收,可以同时被治理.增加磷肥供应率可以抑制复合污染土壤中的镉和硝酸盐向空心菜可食部的转移.

关键词组:基因型变异;重金属;硝酸盐;土壤污染;空心菜


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DOI:

10.1631/jzus.B1700017

CLC number:

X53

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On-line Access:

2018-02-06

Received:

2017-01-12

Revision Accepted:

2017-04-09

Crosschecked:

2018-01-27

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