Abstract
The effect of low pH on net H+ release and root growth of corn (Zea mays L.) and broad bean (Vicia faba L.) seedlings was investigated in short-term experiments at constant pH. Broad bean was more sensitive to low pH than corn: the critical values (pH values below which net H+ release and root growth ceased) were pH 4.00 (broad bean) and pH 3.50 (corn) at 1 millimolar Ca2+. Both proton release and root growth were progressively inhibited as the medium pH declined. Additional Ca2+ in the root medium helped to overcome the limitations of low pH for net H+ release and root growth. Potassium (for corn) and abscisic acid (for broad bean) increased both net H+ release and root growth rate at the critical pH value. It is concluded that poor root growth at low pH is caused by a lack of net H+ release that may decrease cytoplasmic pH values. Inhibited net H+ release at high external H+ activity is not due to a shortage of energy supply to the H+ ATPase. Instead, a displacement of Ca2+ by H+ at the external side of the plasmalemma may enhance reentry of H+ into root cells.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Cramer G. R., Lynch J., Läuchli A., Epstein E. Influx of na, k, and ca into roots of salt-stressed cotton seedlings : effects of supplemental ca. Plant Physiol. 1987 Mar;83(3):510–516. doi: 10.1104/pp.83.3.510. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cramer G. R., Läuchli A., Polito V. S. Displacement of ca by na from the plasmalemma of root cells : a primary response to salt stress? Plant Physiol. 1985 Sep;79(1):207–211. doi: 10.1104/pp.79.1.207. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Glass A. D., Siddiqi M. Y., Giles K. I. Correlations between Potassium Uptake and Hydrogen Efflux in Barley Varieties : A POTENTIAL SCREENING METHOD FOR THE ISOLATION OF NUTRIENT EFFICIENT LINES. Plant Physiol. 1981 Aug;68(2):457–459. doi: 10.1104/pp.68.2.457. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lahaye P. A., Epstein E. Salt toleration by plants: enhancement with calcium. Science. 1969 Oct 17;166(3903):395–396. doi: 10.1126/science.166.3903.395. [DOI] [PubMed] [Google Scholar]
- Marschner H., Handley R., Overstreet R. Potassium Loss and Changes in the Fine Structure of Corn Root Tips Induced by H-ion. Plant Physiol. 1966 Dec;41(10):1725–1735. doi: 10.1104/pp.41.10.1725. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Weisenseel M. H., Dorn A., Jaffe L. F. Natural H Currents Traverse Growing Roots and Root Hairs of Barley (Hordeum vulgare L.). Plant Physiol. 1979 Sep;64(3):512–518. doi: 10.1104/pp.64.3.512. [DOI] [PMC free article] [PubMed] [Google Scholar]