Both chloride (Cl) and sulphate (SO4) were found to impair the uptake
of phosphorus (H2PO4)-P-32 through the roots of potato in a hydroponic
ally conducted experiment. Radioactive phosphorus (P-32) was used as t
he marker. The presence of either Cl and SO4 alone in the nutrient sol
ution made no difference on the impairment Both ions also inhibited th
e long-distance transport of P from roots to shoots. The inhibition by
Cl was much greater than that by SO4, and increased with the concentr
ation of Cl rising from 0 to 15.5 mM in solution.