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American Journal of Plant Nutrition and Fertilization Technology

Year: 2011 | Volume: 1 | Issue: 1 | Page No.: 36-47
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Authors

Ramadan A. Alhendawi

Keywords

Research Article

Comparisons between Effects of Bicarbonate and High pH on Iron Uptake, FeIII Reducing Capacity of the Roots, PEP Carboxylase Activity, Organic Acid Composition and Cation-anion Balance of the Xylem Sap of Maize Seedlings

Ramadan A. Alhendawi
Maize plants were grown in nutrient solution at pH 8 achieved either with bicarbonate (7.5 mM NaHCO3) or HEPES buffer with a comparative treatment, a conventional nutrient solution at pH 5.5, as a control. Measurements were made of growth, Fe concentration and root activities of FeIII reductase and PEP carboxylase. In comparison with the pH 5.5 control, the two high pH treatments depressed growth but the influence of bicarbonate was greater. Shoot and root growth were decreased at both harvests (2 days and 8 days) for bicarbonate and HEPES; in comparison to the control shoot dry weights were lowered by 33 and 19% and root dry weights by 36 and 18%, respectively at the final harvest at day 8. Plant leaves of the bicarbonate treatment were lowest in Fe concentration, with greatest visual evidence of Fe deficiency, both features evident after only 2 days from the start of the treatments. The roots of the bicarbonate plants showed lowest activities of FeIII reductase but highest activities of PEP carboxylase. The xylem sap collected from the bicarbonate treated plants at the final harvest at 8 days showed a lower efflux rate with a slightly higher sap pH (5.31 versus 5.22) as compared with the HEPES treatment. The sap contained higher concentrations of malate, citrate and aconitate and higher concentrations of inorganic cations. The results are discussed in relation to external bicarbonate supply and pH in inducing Fe deficiency in the leaves and on pH regulation in the roots and bleeding sap.
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How to cite this article

Ramadan A. Alhendawi, 2011. Comparisons between Effects of Bicarbonate and High pH on Iron Uptake, FeIII Reducing Capacity of the Roots, PEP Carboxylase Activity, Organic Acid Composition and Cation-anion Balance of the Xylem Sap of Maize Seedlings. American Journal of Plant Nutrition and Fertilization Technology, 1: 36-47.

DOI: 10.3923/ajpnft.2011.36.47

URL: https://scialert.net/abstract/?doi=ajpnft.2011.36.47

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