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

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 N(2) 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 H(2)O 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 CaCl(2) or NaCl in the treatment solution greatly ameliorated the effect of H, CaCl(2) being effective at minute concentration (0.01 meq per liter). NaH(2)PO(4) 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.