钼对低镉水平下小白菜的生长及镉含量的影响

Effect of Molybdenum on Growth and Cadmium Content in Chinese White Cabbage under Low Cadmium Concentration Medium

为了探明低浓度镉污染下,增加钼离子浓度后植物对镉的吸收累积状况,为低浓度镉污染土壤修复提供参考.以"四季上海青"小白菜为材料,采用营养液培养的方式,研究了钼对0.1 mg/L镉水平下小白菜生长、生理指标及镉含量的影响.结果表明:在0.1 mg/L镉浓度培养液中随钼浓度增加,小白菜株高变化不显著,而其地上部鲜重和干重、地下部鲜重和干重、活根系总长度、根投影表面积、活根系总表面积、活根系平均直径、叶绿素a、叶绿素b、叶绿素a+b及类胡萝卜素含量、净光合速率和蒸腾速率、可溶性糖含量、全氮含量等均呈下降趋势,而全钾和全钠含量则有所增加.可见,在0.1 mg/L浓度镉污染土壤上种植小白菜,增加钼肥的施用,会增加小白菜体内镉的累积,增加食用风险.

The objective of this study was to ascertain the status that cadmium was absorbed by Chinese white cabbage in low concentration cadmium and molybdenum supplement medium. The effects of molybdenum ion c oncentratio n （0.05,0.1 mg·L^-1）on the growth, cadmium content and physiological indexes under cadmium treatment（0.1 mg·L^-1） were studied on the basis of Hoagland nutrition. The results showed no significant difference in plant height by increasing molybdenum concentrations , while fresh weight （F.W）and dry weight （D.W） aboveground and underground, total root length,total project area, total root surfer area,total average diameter, chlorophyll a, chlorophyll b, chlorophyll a＋b and carotenoid contents, net photosynthetic rate and transpiration rate had the trend of decreasing, and cadmium content aboveground of Chinese white cabbage had a trend of increasing. With molybdenum concentrations increasing under cadmium treatment, solubility sugar and total nitrogen contents had the trend of reducing, while total kalium and total sodium contents had the trend of increasing. So the increased molybdenum concentrations could induce plant to increase the absorption of cadmium in low concentration cadmium（0.1 mg·L^-1）, and enhance the consumption risk.