Nutrition Influence on Copper Accumulation by Brassica pekinensis Rupr.

Effect of nutrition status in the growth medium on Cu accumulation and plant growth were tested in Brassica pekinensis grown in hydroponic culture in a cultural facility. Cu concentration in the roots and shoots increased with increasing external Cu in the culture solution. On the other hand, it decreased with increasing Hoaglandʹs solution (HS) strength. Interaction between external Cu and HS strength was also observed to affect Cu concentration in the tissues. A low level of external Cu could lead to a high Cu concentration in the plant at low HS strength, while to obtain a high Cu concentration in the plant at high HS strength, a high level of external Cu was needed. Partial nutrient experiments showed an important role of Fe and P in governing Cu accumulation. The influence of nutrients on Cu accumulation were mainly attributed to the osmolarity of the nutrient solution, antagonism between nutrients and Cu, pH change, and cation transporter induction. Root length and shoot biomass were negatively related to Cu concentration in the plant, suggesting an adverse effect of Cu in the tissue on plant growth. Root biomass showed less response to Cu concentration in the plant. This was presumably due to plant resource allocation between shoot and root, by which more resources were shifted to the Cu-stressed roots. The results might have important implications in understanding the sterility of the growth media of plants on Cu fate and effect in the ecosystem.