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This article in AJ

  1. Vol. 63 No. 5, p. 770-772
    Received: Feb 22, 1971

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Radicle Elongation of Pea Seedlings as Affected by Oxygen Concentration and Gradients between Shoot and Root1

  1. B. W. Eavis,
  2. H. M. Taylor and
  3. M. G. Huck2



Pea seedlings grown in divided gas-tight containers were arranged so that O2 concentration of soil air around the radicles could be varied independently of that around the cotyledons and plumules. When the soil around the radicle tip contained 0.21 atm O2, no significant reduction in radicle elongation rate was observed until the gas mixture surrounding the cotyledons was reduced below 0.10 atm partial pressure. Even with O2 partial pressure at 0 around the cotyledons radicle elongation rate was 50% as high as that of the controls.

When O2 concentration around the radicle was varied, while that around the cotyledons remained at 0.21 atm, the radicle elongation rate at a given O2 level was markedly reduced. At zero O2 around the radicle elongation rate was only 20% of normal. It is suggested that a high diffusion impedance between internal gas channels and the relatively undifferentiated tissues near the root tip limits O2 supply to respiring tissue.

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