Lettuce grown in silver laden soil at two different activity levels of soil microorganisms

Lettuce biomass, silver accumulation in lettuce, and effect of activity of soil microoorganisms on these items, were studied in a series of experiments, Lettuce was cultivated in two kinds of soil with different organic matter concentrations. Initially the soil was either sterile or non-sterile, and had been supplied with different silver nitrate concentrations. Lettuce growth was significantly negatively affected by silver, especially in initially sterile soil with lower organic matter content. There was also a significantly enhanced silver accumulation at larger silver supply in initially sterile soil with the lower organic matter content, otherwise there was no enhanced silver accumulation. There was a significant difference in respiration rate after hervest between the initially sterile soil and the non-sterile soil. In soil withthe lower organic matter content, microorganism activity was inhibited by silver. In conclusion; silver accumulation increased and growth deceased in the lettuce grown in soil containing silver when the microorganism community in the soil had been affected by sterilization. The negative effects of silver on both lettuce and microorganisms were more distinct when the soil had lower organic matter content.