Crassulacean acid metabolism species differ in the contribution of C and C carboxylation to end of day CO fixation.

Crassulacean acid metabolism (CAM) is a photosynthetic pathway that temporally separates the nocturnal CO uptake, via phosphoenolpyruvate carboxylase (PEPC, C carboxylation), from the diurnal refixation by Rubisco (C carboxylation). At the end of the day (CAM-Phase IV), when nocturnally stored CO has depleted, stomata reopen and allow additional CO uptake, which can be fixed by Rubisco or by PEPC. This work examined the CO uptake via C and C carboxylation in phase IV in the CAM species Phalaenopsis "Sacramento" and Kalanchoe blossfeldiana "Saja.

CAM-physiology and carbon gain of the orchid Phalaenopsis in response to light intensity, light integral and CO.

The regulation of photosynthesis and carbon gain of crassulacean acid metabolism (CAM) plants has not yet been disclosed to the extent of C3-plants. In this study, the tropical epiphyte Phalaenopsis cv. "Sacramento" was subjected to different lighting regimes.

Photosynthetic quantum yield dynamics: from photosystems to leaves.

The mechanisms underlying the wavelength dependence of the quantum yield for CO(2) fixation (α) and its acclimation to the growth-light spectrum are quantitatively addressed, combining in vivo physiological and in vitro molecular methods. Cucumber (Cucumis sativus) was grown under an artificial sunlight spectrum, shade light spectrum, and blue light, and the quantum yield for photosystem I (PSI) and photosystem II (PSII) electron transport and α were simultaneously measured in vivo at 20 different wavelengths. The wavelength dependence of the photosystem excitation balance was calculated from both these in vivo data and in vitro from the photosystem composition and spectroscopic properties.

Photosynthetic acclimation in relation to nitrogen allocation in cucumber leaves in response to changes in irradiance.

Leaves deep in canopies can suddenly be exposed to increased irradiances following e.g. gap formation in forests or pruning in crops.

Blue light dose-responses of leaf photosynthesis, morphology, and chemical composition of Cucumis sativus grown under different combinations of red and blue light.

The blue part of the light spectrum has been associated with leaf characteristics which also develop under high irradiances. In this study blue light dose-response curves were made for the photosynthetic properties and related developmental characteristics of cucumber leaves that were grown at an equal irradiance under seven different combinations of red and blue light provided by light-emitting diodes. Only the leaves developed under red light alone (0% blue) displayed dysfunctional photosynthetic operation, characterized by a suboptimal and heterogeneously distributed dark-adapted F(v)/F(m), a stomatal conductance unresponsive to irradiance, and a relatively low light-limited quantum yield for CO(2) fixation.

An artificial solar spectrum substantially alters plant development compared with usual climate room irradiance spectra.

Plant responses to the light spectrum under which plants are grown affect their developmental characteristics in a complicated manner. Lamps widely used to provide growth irradiance emit spectra which are very different from natural daylight spectra. Whereas specific responses of plants to a spectrum differing from natural daylight may sometimes be predictable, the overall plant response is generally difficult to predict due to the complicated interaction of the many different responses.

The responses of light interception, photosynthesis and fruit yield of cucumber to LED-lighting within the canopy.

Mathematical models of light attenuation and canopy photosynthesis suggest that crop photosynthesis increases by more uniform vertical irradiance within crops. This would result when a larger proportion of total irradiance is applied within canopies (interlighting) instead of from above (top lighting). These irradiance profiles can be generated by Light Emitting Diodes (LEDs).