Leaf mineral concentration of Citrus aurantium (sour
orange tree) was measured at bi-monthly intervals from 30 to 85 months
of exposure in a long-term study on the effects of a 300 µmol
mol−1 enrichment of atmospheric CO2, under
conditions of high nutrient and water supply. There were clear
seasonal trends in the concentrations of most of the elements studied.
There were initial decreases in the leaf concentrations of N and the
xylem-mobile, phloem-immobile elements Mn, Ca and Mg, as well as a
significant and sustained increase in the leaf concentration of B, and
no changes in the concentrations of K, Fe, Na, P, S, Zn and Cu.
Interestingly, the initial reductions in the leaf concentrations of
Mn, N, Ca and Mg gradually disappeared with time.