This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (44) Citing Articles via Google Scholar Google Scholar Articles by Steer, B. T. Search for Related Content PubMed PubMed Citation Articles by Steer, B. T. Agricola Articles by Steer, B. T.

Articles

Diurnal Variations in Photosynthetic Products and Nitrogen Metabolism in Expanding Leaves

Division of Irrigation Research, Commonwealth Scientific and Industrial Research Organization, Griffith, N.S.W., Australia

Expanding leaves of Capsicum frutescens L. cv. California Wonder, Cucumis melo L. cv. Hales Best, and Citrus sinensis L. Osbeck cv. Washington Navel showed a marked diurnal periodicity in the incorporation of ¹⁴C from photosynthetically fixed ¹⁴CO₂ into amino acids. Incorporation was virtually nil at the beginning of the photoperiod, reached a maximum in the 6th to 7th hour and decreased during the latter part of the photoperiod. In Capsicum frutescens this was apparently a reflection of the availability of reduced nitrogen controlled by the activity of nitrate reductase in the leaves. This also controlled the periodicity of the incorporation of ¹⁴C into fraction I protein. Possible control mechanisms and the relation of nitrogen metabolism to the periodicity of leaf expansion growth are discussed.