Potassium Loss and Changes in the Fine Structure of Corn Root Tips Induced by H-ion

Abstract

The effects of H, Ca, and anaerobiosis upon loss of K to ambient solutions, upon changes in the fine structure, and upon the respiration of corn root tissue were studied. In the pH range 5.5 to 8.0 losses of K decreased with decreasing H concentration. Ca reduced K loss greatly in the lower part of the pH range but with increasing pH the effect of Ca declined. Losses of K under N₂ were much greater than those measured under air but the same effects of H and Ca were found. The effect of phosphate upon K loss was found to depend upon pH, temperature and the state of development of the tissue.

In pure H₂O or dilute HCl no obvious derangement of the fine structure of meristematic cells was found to occur in 3 hours above pH 4.4 except attenuation of the groundplasm. At pH 4.4 and below, serious injury was found. The presence of CaCl₂ or NaCl in the treatment solution greatly ameliorated the effect of H, CaCl₂ being effective at minute concentration (0.01 meq per liter). NaH₂PO₄ was without any great effect. Anaerobiosis at neutral pH produced severe tissue damage.

In contrast to anaerobic treatments, aerobic treatments (pH 5.8) resulting in large losses of K were not accompanied by any diminution of the respiratory rate.

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