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Analysing Partitioning Of Recently Fixed And Of Reserve Carbon In Reproductive Phaseolus Vulgaris L. Plants, Donald Geiger, Wen-Jang Shieh
Analysing Partitioning Of Recently Fixed And Of Reserve Carbon In Reproductive Phaseolus Vulgaris L. Plants, Donald Geiger, Wen-Jang Shieh
Donald R. Geiger
Partitioning of recently-fixed carbon among plant organs and subsequent distribution of reserve carbon were studied by supplying whole shoots of bean plants (Phaseolus vulgaris L.) with 14C-labelled CO2 of constant specific radioactivity throughout a photoperiod. The gain of tracer carbon in each part revealed net accumulation of recently-fixed carbon from direct fixation, import or both. Growth rate coefficients describing the present pattern of plant growth were calculated from ratios of tracer carbon to total carbon present in plant organs and were used to project future plant form. The period 10–20 d after the start of flowering was marked by a …
Sources Of Carbon For Export From Spinach Leaves Throughout The Day, Jerome Servaites, Bernadette Fondy, Bin Li, Donald Geiger
Sources Of Carbon For Export From Spinach Leaves Throughout The Day, Jerome Servaites, Bernadette Fondy, Bin Li, Donald Geiger
Donald R. Geiger
Rates of net carbon exchange, export, starch, and sucrose synthesis were measured in leaves of spinach (Spinacia oleracea L.) throughout a 14-hour period of sinusoidal light to determine the sources of carbon contributing to export. Net carbon exchange rate closely followed light level, but export remained relatively constant throughout the day. In the morning when photosynthesis was low, starch degradation provided most of the carbon for export, while accumulated sucrose was exported during the evening. At high photosynthesis rate, the regulatory metabolite fructose 2,6-bisphosphate was low, allowing more of the newly fixed carbon to flow to sucrose through cytosolic fructose …