Selective absorption of iron from iron chelates by soybean plants

Abstract

Chlorotic and green soybean plants were placed in solutions of Fe55 or C14 labeled chelates to compare chelate components absorbed. Assays (cps/ml) of exudate from the stems of chlorotic plants gave a ratio of Fe55 C14 = 10,033 : 6. Similar assays for green plant exudate gave a ratio of 64 : 6. Fe55 and C14 in the exudate moved electrophoretically toward the anode at rates generally different from those of the intact chelates supplied to the roots. Chlorotic intact plants absorbed much more Fe55 than green plants, but chlorotic and green plants absorbed similar amounts of C14, suggesting the non-dependence of the absorption-translocation rates for these isotopes. Synthetic chelating agents delivered Fe to the roots; very little emphasis can be placed on their role in the translocation of Fe within the plants.