| Abstract: | The uptake and distribution of copper was examined in chicory (Cichorium intybus L. cv. Grasslands Puna) and tomato (Lycopersicon esculentumMill. cv. Rondy) plants grown in a Nutrient Film Technique System (NFT) with addition of 0.05, 5, 10 and 20 mg Cu L-1. Biomass production of shoots and roots of both chicory and tomato was strongly depressed by Cu concentrations higher than
5 mg Cu L-1 in the rooting media. Although Cu concentrations in both shoots and roots of both species increased with increasing Cu concentrations
in the rooting media, the increase in roots was very much greater than that in shoots, in which the range of concentrations
was small. A large proportion of total Cu uptake was retained by roots except when plants were grown in solution Cu concentrations
of 0.05 mg Cu L-1. Copper retention by roots limited Cu translocation to xylem and shoots. Copper adsorption by the root appears to buffer
against increases of Cu in the rooting media. A cupric-sensitive electrode used in conjunction with total Cu analysis by graphite
furnace atomic absorption spectrophotometry (GFAAS) indicated that more than 99.6% of total Cu in xylem sap was in a complexed
form. Large differences between measured and predicted Cu accumulation by shoots of tomato (0.134–0.243 mg Cu plant-1, 0.660–4.274 mg Cu plant-1, respectively) and chicory (0.095–0.203 mg Cu plant-1, 0.626–1.620 mg Cu plant-1, respectively) suggest that some xylem transported Cu is recirculated to roots via the phloem.
This revised version was published online in June 2006 with corrections to the Cover Date. |
