The Effect And Mechanism Of Silicon On Alleviating Cadmium Contamination Of Chinese Cabbage

Soil, one crucial natural resources for human society, is facing the increasingly austere position for heavy metal pollution. Cadmium is ubiquitous in the soil, easy to transport and accumulate in vegetables, therefore, affect its biomass and quality. Furthermore Cd is harmful to people's health via food chain transportation.Pot experiment was conducted to investigate the effect and mechanism of silicon to alleviate Cd contamination in Chinese cabbage. Result showed that adding silicon is an effective way to mitigate Cd toxicity and alleviate Cd contamination of Chinese cabbage grown in contaminated soil. Silicon increased soil pH and available Si content significantly but decreased available Cd content, which can be considered as an important mechanism. The biomass and height and POD activity promoted while SOD activity decreased, with proper Si(0.5, 1.0 g/kg), the chlorophyll SPAD values and CAT activity elevated but membrane permeability decreased, so the growth and the physiology improved to some degree. While with higher Si(2.0 g/kg), phytotoxicity arosed by Na~+ with incidences of lower chlorophyll values and CAT activity but higher membrane permeability were detected. Si significantly reduced the Cd concentration and the total Cd in shoots, roots, stems and leavies. The root aborption index (RAI) and shoot absorption index (SAI) of cadmium as well as the primary transport index (PTI) and the secondary transport index (STI) and the shoot transport index were significantly decreased. The inhibitory effect of Si on Cd uptake and transport became more significant under Cd stress deteriorated. Si concentration and totoal Si increased with its distribution roots > leavies > stems and leavies > stems > roots separately. Similar the distribution orderliness between Cd and Si, there may be Si-Cd compounds in plant tissues to alleviate cadmium toxicity.