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The uptake of sulphur, calcium, and magnesium and their distribution in Phaseolus vulgaris L. as affected by cyclohexanecarboxylic acid

University of British Columbia

Cyclohexanecarboxylic acid (CHCA) has one of the lowest molecular weights of the naphthenic acids, a group of compounds which have been recognized recently as stimulators of plant growth and metabolism. Potassium cyclohexanecarboxy-late's (KCHC) effects on the mineral nutrition of bush bean plants (Phaseolus vulgaris L., cultivar Top Crop) were examined in four separate studies. 1. The foliage of two-week-old plants, growing in sulphur-free nutrient solution was treated with 1 X 10⁻² M KCHC solution and subsequently the roots were given a 4 hr exposure to 35[sub SO₄] in the nutrient solution. Slightly more sulphur-35 was taken up by treated plants than untreated control plants, but the difference was not statistically significant. However, significantly more sulphur-35 was detected in the leaves of treated plants. The differences in distribution were attributed to metabolic changes brought about by treatment. 2. Plants were handled as above and the leaves were harvested one, two, and five days after feeding sulphur-35. The leaf tissue was separated, chemically, into sulphate, lipid, free amino acid, perchloric acid soluble, and protein fractions. A portion of the protein fraction was hydrolyzed to permit separation of the sulphur-amino acids by chromatography. The bulk of the sulphur-35 was incorporated into the acid soluble fraction first and subsequently into the protein fraction. KCHC treated leaves contained significantly more acid soluble S initially and more protein S finally than control leaves. Control leaves contained more sulphate S than treated leaves two days after sulphur-35 feeding. These results indicated that KCHC treatment stimulated the incorporation of sulphur into protein, and this was consistent with other reports of increased protein formation due to naphthenate treatment. 3. Bush bean plants growing in complete nutrient solution were treated and exposed to calcium-45. Treated plants took up slightly less calcium than controls, and they retained significantly more of it in their roots. These results are in contrast to the effect of treatment on sulphur-35 uptake and distribution. Bush bean plants growing in complete nutrient solution were treated with KCHC solution at two weeks of age. One week later the distribution of sulphur, calcium, and magnesium was examined in leaf blades, stems plus petioles, and roots. No significant effect of treatment on uptake was found for any of the elements. Distribution of sulphur and calcium within the plant was not affected by treatment, but control plants contained significantly more magnesium in their leaves than treated plants. The lack of significant effect on ion uptake indicated that the increased growth found in many studies, when plants were treated with naphthenic acids, apparently was not the result of improved uptake of sulphur, calcium, or magnesium.

Text

2011-03-23

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http://hdl.handle.net/2429/32828

Botany

University of British Columbia

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