Coupled land surface and terrestrial ecosystem models are used to simulate energy and carbon fluxes over winter wheat at the Ponca City, Oklahoma, Ameriflux site. The terrestrial ecosystem model consists of photosynthesis and respiration (autotrophic and heterotrophic) sub-modules, which uses canopy temperature, soil moisture, and soil temperature simulated by the land surface scheme. The photo...

We examined the effects of elevated carbon dioxide concentration ([CO2]) on the relationship between light-saturated net photosynthesis (A(sat)) and area-based foliar nitrogen (N) concentration (N(a)) in the canopy of the Duke Forest FACE experiment. Measurements of A(sat) and N(a) were made on two tree species growing in the forest overstory and four tree species growing in the forest understo...

Abstract In order to evaluate crop water stress index (CWSI) and canopy temperature of wheat cultivars under terminal drought stress, a field experiment was conducted at the Agricultural Research Station of Shiraz University, Shiraz, during 2009 growing season. Five wheat cultivars including Shiraz, Bahar, Pishtaz, Sistan and Yavaros and four levels of water regime including well watering [Irr...

Rates of photosynthesis, sucrose synthesis, starch accumulation and degradation were measured in sugar beet (Beta vulgaris L.) and bean (Phaseolus vulgaris L.) plants under a square-wave light regime and under a sinusoidal regime that simulated the natural daylight period. Photosynthesis rate increased in a measured manner in direct proportion to the increasing light level. In contrast to this ...

Photosynthesis is a process that indicates the productivity of crops. The estimation this variable can be achieved through methods based on mathematical models. Mathematical models are usually classified as empirical, mechanistic, and hybrid. To mathematically model photosynthesis, it essential to know: input/output variables their units; modeling used its classification (empirical, or hybrid);...

BACKGROUND Many aquatic photosynthetic microorganisms possess an inorganic-carbon-concentrating mechanism that raises the CO2 concentration at the intracellular carboxylation sites, thus compensating for the relatively low affinity of the carboxylating enzyme for its substrate. In cyanobacteria, the concentrating mechanism involves the energy-dependent influx of inorganic carbon, the accumulati...

The effects of various calcium ion antagonists and ion transport inhibitors on photosynthetic O(2) evolution of corals, isolated zooxanthellae, sea anemone tentacles, and Chlorococcum oleofaciens were measured. Only the phenothiazine drugs were effective at inhibiting photosynthesis. Trifluoperazine, a calcium ion antagonist drug, inhibited at low concentrations, with 10(-4) molar and 8 x 10(-6...

Chlorella pyrenoidosa were allowed to photosynthesize for short periods of time in the presence of (14)CO(2) and HTO. Analysis of tritium and (14)C labeling of photosynthetic intermediate compounds showed that the T/(14)C ratio of glycolic acid was comparable to that of intermediate compounds of the photosynthetic carbon reduction cycle when photosynthesis was performed in nearly 100% oxygen an...