Absorption and accumulation of Cd in corn: effects by soil water contents
土壤水分变化对玉米苗期吸收积累镉的影响

Cadmium (Cd) contamination in soil has become one of the environmental issues receiving increasing attention worldwide. Cd contamination is resulted from several human economic activities: the application of municipal sewage sludge, atmospheric deposition of Cd, mining activities, application of chemical fertilizers and pesticides. Cd can be transferred to crop plants, and is often accumulated to concentrations exceeding their levels in the soil by many times. The effects of soil water contents (35%, 45%, 55%, 65%, 75% and 85% of field moisture capacity) on uptake and accumulation of Cd by corn (Zea mays var. Tiandan No. 8) were investigated in greenhouse experiment. The results showed that both corn biomass (shoot and root) and Cd content varied with soil water contents at different growth stages. At 22d after emergence, the aboveground and underground biomass of corn increased with increasing soil water content, while at 16d corn biomass for field moisture capacity of 35% and 85% were lower than those for other soil water contents. At 16d and 22d, Cd concentration in the shoot reached the maximum, 55.41mg/kg and 39.33mg/kg with field moisture capacity of 55%; while the lowest Cd concentrations of 27.97mg/kg and 23.52mg/kg, were found for the treatment with field moisture capacity of 85%. Due to root activities, Cd concentration in soil solution decreased with corn growth. Soil water contents affected the availability of Cd in soil. Cd concentration in soil solution for field moisture capacity of 65% was higher than that for field moisture capacity of 75% or 85%. There was stronger positive correlation between total Cd uptake by corn and transpiration.