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C¹⁴ DISTRIBUTION IN PHOTOSYNTHATE OF TOMATO AS INFLUENCED BY SUBSTRATE COPPER AND MOLYBDENUM LEVEL AND NITROGEN SOURCE
P. M. GIORDANO, H. V. KOONTZ and E. J. RUBINS
Plant and Soil
Vol. 24, No. 3 (June 1966), pp. 437-446
Published by: Springer
Stable URL: http://www.jstor.org/stable/42932202
Page Count: 10
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The influence of nitrogen source and micronutrient treatment on the apportionment of C¹⁴ in alcohol extracts was studied in tomato. Plants were exposed at several stages of maturity to C¹⁴O₂ and the ethanol-soluble photosynthate fractionated into sugars, organic acids, and amino acids. Ammonium-treated plants had low levels of organic acids at all stages of maturity, suggesting a rapid conversion to amino acid residues. However, the addition of copper in the absence of molybdenum resulted in increased labelling of the organic acid fraction under nitrate nutrition. The amino acid fraction was reduced at some stages of growth under these conditions. This may indicate that copper interferes with the role of molybdenum in the enzymatic reduction of nitrate. Measurement of the total quantity of some individual free amino acids indicated more efficient utilization of these for protein synthesis in the presence of copper. On the other hand, assay of the C¹⁴-activity of individual free amino acids showed that degree of label bore little relation to micronutrient treatment.
Plant and Soil © 1966 Springer