The castor oil plants were harvested 74 days after sowing, and the
shoots were separated from the roots at harvest. The shoots were washed
with tapwater followed bywashingwith a solution of 1% HCl and distilled
water. Roots were sieved, washed and soaked for 90 min in a solution of
0.02 mmol L−1 EDTA (disodium salt). After soaking, the roots were
washed again with distilled water. Plant samples were washed, dried,
weighed and then digested using HNO3/H2O2 in a microwave oven
prior to the elemental/nutritional analysis.