title: Diurnal variations in photosynthetic products and nitrogen metabolism in expanding leaves.
abstract: 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 (14)C from photosynthetically fixed (14)CO(2) 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 (14)C into fraction I protein. Possible control mechanisms and the relation of nitrogen metabolism to the periodicity of leaf expansion growth are discussed.
authors: Division of Irrigation Research, Commonwealth Scientific and Industrial Research Organization, Griffith, N.S.W., Australia.
authors: B T
authors: BT
authors: Steer