1. Photoxidation in leaves is measured by exposing them to light in an atmosphere free from carbon dioxide but containing varied percentages of oxygen. 2. Photoxidation is observed in living leaves as well as in dead ones and in plant juices. Its rate is only slightly enhanced by feeding the leaves with sugar, but the respiration (autoxidation) becomes considerably enlarged during the exposure ...

The response of the marine diatom Phaeodactylum ,tricornutum to Fe deficiency was evaluated in the context of fundamental physiological models of growth and photosynthesis. Fe deficiency induced chlorosis, which decreased Chl a : C ratios and Chl a-specific light-saturated photosynthesis (P,“). In contrast to Pme, (Ye was slightly increased under Fe deficiency, and photosynthesis in Fedeficient...

Seed oil content is an important trait of nut seeds, and it is affected by the import of carbon from photosynthetic sources. Although green leaves are the main photosynthetic organs, seed sarcotesta photosynthesis also supplies assimilates to seed development. Understanding the relationship between seed photosynthesis and seed development has theoretical and practical significance in the cultiv...

Nonlinear responses of photosynthesis to the CO2 concentration at which plants were grown (Cg) have been often reported in the literature. This study was designed to develop mechanistic understanding of the nonlinear responses with both experimental and modelling approaches. Soybean (Glycine max) was grown in five levels of Cg (280, 350, 525, 700, 1000 ppm) with either a high or low rate of nit...

Nonlinear responses of photosynthesis to the CO2 concentration at which plants were grown (Cg) have been often reported in the literatu~e. This study was designed to develop mechanistic understanding of the nonlinear responses with both experimental and modelling approaches. Soybean (Glycine max) was grown in five levels of Cg (280, 350, 525, 700, 1000 ppm) with either a high or low rate of nit...

Chloroplasts isolated by methods similar to that described by Arnon et al. (1) are capable of incorporating acetate carbon into both lipid and n)on-lipid materials when fortified with appropriate cofactors (2, 3,4, 5). The actual rate of incorporation of acetate carbon in these preparations was, however, very small compared with the normal rate of photosynthesis (1-2 jumoles/mg chlorophyll'hr) ...

Steady state, nutrient-saturated phytoplankton growth can be quantitatively described by four equations: an empirical equation relating growth rate ~1, to absorbed irradiance [; a different equation relating b and 4 derived from the empirical equation relating instantaneous rate of gross photosynthesis to irradiance; an empirical equation relating the respiratory rate constant R, to growth rate...

The activity and extent of light activation of three photosynthetic enzymes, pyruvate,Pi dikinase, NADP-malate dehydrogenase (NADP-MDH), and fructose 1,6-bisphosphatase (FBPase), were examined in maize (Zea mays var Royal Crest) leaves relative to the rate of photosynthesis during induction and under varying light intensities. There was a strong light activation of NADP-MDH and pyruvate,Pi diki...

In the modern ocean, a significant amount of nitrogen fixation is attributed to filamentous, nonheterocystous cyanobacteria of the genus Trichodesmium. In these organisms, nitrogen fixation is confined to the photoperiod and occurs simultaneously with oxygenic photosynthesis. Nitrogenase, the enzyme responsible for biological N2 fixation, is irreversibly inhibited by oxygen in vitro. How nitrog...

CO(2) exchange between air and leaf is conceived as a current along a resistor with a respiratory current, unaffected by CO(2) concentration, entering the resistor. The conclusion follows that a plant placed in an atmosphere free of CO(2) will increase the CO(2) concentration to the compensation concentration along a curve determined by the resistor and the volume of the atmosphere. This was ve...