| As the increasing heavy metals pollution of the farmland, vegetable production is easily endangered by Cd contamination, which is one of the most toxic heavy metals to both plants and animals. For this reason, the selection of vegetable cultivars with low Cd accumulation in edible parts is an efficient approach to guarantee the safety of vegetables.64 cultivars of tomato and 34 cultivars of brassica chinensis were chosen to be grown in the Cd-contaminated fluvo-aquic soil in Zhuzhou surburbs, the research aimed to study the differences in the quality of edible part of the vegetables and the capacibility of Cd uptake, accumulation among different tissues through field experiment. After the high and low Cd uptake ability by shoot of two brassica chinensis varieties were determined, a pot experiment was carried out to study the effect of dfferent treatments of foliar fertilizers on growth and quality, Cd uptake characteristics and Cd distribution, mineral elements and amino acids content in brassica chinensis. The main results are listed as follows:1. Variations in Cd content of root, shoot and leaf, fruit among tested cultivars had extreme significance(p<0.01) under Cd polluted field. The Cd contents of different organs of tomato were found in the order of root>stem and leaf>fruit. The Cd content of fruit varied from 0.035 to 0.108 mg/kg FW, over-limit rate was up to 95.3%, the risk seemed to be especially high for the cherry type cultivars. The 3 chosen low-Cd uptake cultivars could be recommended to grow on the light Cd-exposure soil. The correlation of Cd content between root, stem and leaf was extremely significant, but there was no significant correlation between vegetative tissues and fruit.2. Variations in Cd content of shoot and root among 34 cultivars of brassica chinensis had extreme significance(p<0.01) and significance(p<0.05) respectively under Cd polluted field. The Cd contents of brassica chinensis were found in the order of root>shoot, the correlation of Cd content between shoot and root was extremely significant. The over-limit rate in shoot of brassica chinensis was 100%, so it is not suggested to plant brassica chinensis on the Cd-polluted soils.3. The pot-experiment indicated, all the foliar applications could promote growth and quality of two kinds of brassica chinensis compared with the control. The yield, chlorophyll content in leaves(SPAD value) and Vc of brassica chinensis were enhanced by treatments, while the nitrate content was decreased except treatment 4(Zn).For mineral elements foliar spray, for the brassica chinensis variety with high Cd accumulation, the Cd content of shoot was declined by the treatments while the root Cd content of brassica chinensis was increased except treatment 7(Fe), treatment 5(Ca) was the best; For the brassica chinensis variety with low Cd accumulation, the Cd content of shoot was decreased by the treatments while the root Cd content of brassica chinensis was raised except treatment 4(Zn), treatment 8(Mg) was the best; the Cd distribution of brassica chinensis was affected and the corresponding elements content in leaves of brassica chinensis was increased. For amino acids foliar spray, the Cd content and accumulation of shoot and root were increased by the treatments, Cd absorption of brassica chinensis promoted treatments except treatment 9(Pro).4.Pot culture experiment also confirmed that, the Cd concentration, accumulation and distribution coefficient in the shoot of brassica chinensis were decreased more by foliar spraying of combination B, Ca and Si than one of them, the BSi and CaSi combination treatments were the optimum. |
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