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Measurements were made of the uptake of ammonium and nitrate by successive zones of the radicle of intact seedlings of Pisum sativum L. A modified version of the potometer designed by Gregory and Woodford (1939) was used to supply separate zones, and the amounts of nitrogen absorbed were determined with the stable isotope lON.
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Grasmanis et al. (1969) studied this question.
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