T1 - The quantum yield for CO2 uptake in C3 and C4 grasses

T1 - Photosynthetic responses of C3 and C4 species from cool shaded habitats in Hawaii
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C3 and C4 Photosynthesis (PDF Download Available)

Consequences of C4 photosynthesis for the partitioning of growth: a test using C3 and C4 subspecies of Alloteropsis semialata under nitrogen-limitation.

Differential sensitivity to humidity of daily photosynthesis in the field in C3 and C4 species[J].
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between C3 and C4 plants is the quantum yield …

AB - Arundo donax has attracted interest as a potential bioenergy crop due to a high apparent productivity. It uses C3 photosynthesis yet appears competitive with C4 grass biomass feedstock's and grows in warm conditions where C4 species might be expected to be that productive. Despite this there has been no systematic study of leaf photosynthetic properties. This study determines photosynthetic and photorespiratory parameters for leaves in a natural stand of A. donax growing in southern Portugal. We hypothesise that A. donax has a high photosynthetic potential in high and low light, stomatal limitation to be small and intrinsic water use efficiency unusually low. High photosynthetic rates in A. donax resulted from a high capacity for both maximum Rubisco (Vc,max 117 μ1/4mol CO2 m-2 s-1) and ribulose-1:5-bisphosphate limited carboxylation rate (Jmax 213 μ1/4mol CO2 m-2 s-1) under light-saturated conditions. Maximum quantum yield for light-limited CO2 assimilation was also high relative to other C3 species. Photorespiratory losses were similar to other C3 species under the conditions of measurement (25%), while stomatal limitation was high (0.25) resulting in a high intrinsic water use efficiency. Overall the photosynthetic capacity of A. donax is high compared to other C3 species, and comparable to C4 bioenergy grasses.

A mechanistic model for the photosynthesis-light response based on the photosynthetic electron transport of photosystem II in C3 and C4 species[J].
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In general, photosynthesis can function without harm between 0 and 30 °C in cold-adapted plants that are active in winter and early spring, or grow at high altitude and latitude. Photosynthesis shows an optimum temperature that roughly corresponds to the middle of the non-harmful range, and drops off with increasing slope as temperatures rise above the thermal optimum. At lower temperatures, the quantum yield of C3 plants is higher than that of C4 plants, indicating that photosynthesis in C3 plants is more efficient at lower temperatures. After the saturation point, photosynthesis is CO2 limited reflecting the inability of the Calvin cycle enzymes to keep pace with the absorbed light energy that is producing ATP and NADPH. Light saturation levels for shade plants are substantially lower than those for sun plants. These levels usually reflect the maximum photon flux to which the leaf was exposed during growth.

The orientations of core antenna chlorophylls in photosystem II are optimized to maximize the quantum yield of photosynthesis.
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title = "Photosynthetic responses of C3 and C4 species from ..

Arundo donax has attracted interest as a potential bioenergy crop due to a high apparent productivity. It uses C3 photosynthesis yet appears competitive with C4 grass biomass feedstock's and grows in warm conditions where C4 species might be expected to be that productive. Despite this there has been no systematic study of leaf photosynthetic properties. This study determines photosynthetic and photorespiratory parameters for leaves in a natural stand of A. donax growing in southern Portugal. We hypothesise that A. donax has a high photosynthetic potential in high and low light, stomatal limitation to be small and intrinsic water use efficiency unusually low. High photosynthetic rates in A. donax resulted from a high capacity for both maximum Rubisco (V-c,V- max 117 mu mol CO2 m(-2) s(-1)) and ribulose-1:5-bisphosphate limited carboxylation rate (J(max) 213 mu mol CO2 m(-2) s(-1)) under light-saturated conditions. Maximum quantum yield for light-limited CO2 assimilation was also high relative to other C3 species. Photorespiratory losses were similar to other C3 species under the conditions of measurement (25%), while stomatal limitation was high (0.25) resulting in a high intrinsic water use efficiency. Overall the photosynthetic capacity of A. donax is high compared to other C3 species, and comparable to C4 bioenergy grasses.

the maximum quantum yield of C4 photosynthesis ..

Light is a critical resource for plants that can limit growth and reproduction. When photosynthesis rates are plotted against light intensity, the result is a photosynthesis light response curve (Figure 8). In the dark, there is no photosynthetic carbon assimilation, and instead CO2 is given off by the plant because of mitochondrial respiration. By convention, CO2 assimilation is negative in this part of the light-response curve. As the photon flux increases, photosynthetic CO2 assimilation increases linearly until it equals CO2 release by mitochondrial respiration. The point at which photosynthetic CO2 uptake exactly balances CO2 release is called the light compensation point. Increasing light above the light compensation point proportionally increases photosynthesis, indicating that photosynthesis is limited by the rate of electron transport, which in turn is limited by the amount of available light. This portion of the curve is referred to as light-limited. Further increases in photosynthesis are eventually limited by the carboxylation capacity of RubisCO or the metabolism of triose phosphates. This part of the curve is referred to as CO2-limited.

the quantum yield of C3 photosynthesis is directly ..

Arundo donax has attracted interest as a potential bioenergy crop due to a high apparent productivity. It uses C3 photosynthesis yet appears competitive with C4 grass biomass feedstock's and grows in warm conditions where C4 species might be expected to be that productive. Despite this there has been no systematic study of leaf photosynthetic properties. This study determines photosynthetic and photorespiratory parameters for leaves in a natural stand of A. donax growing in southern Portugal. We hypothesise that A. donax has a high photosynthetic potential in high and low light, stomatal limitation to be small and intrinsic water use efficiency unusually low. High photosynthetic rates in A. donax resulted from a high capacity for both maximum Rubisco (V-c,V- max 117 mu mol CO2 m(-2) s(-1)) and ribulose-1:5-bisphosphate limited carboxylation rate (J(max) 213 mu mol CO2 m(-2) s(-1)) under light-saturated conditions. Maximum quantum yield for light-limited CO2 assimilation was also high relative to other C3 species. Photorespiratory losses were similar to other C3 species under the conditions of measurement (25%), while stomatal limitation was high (0.25) resulting in a high intrinsic water use efficiency. Overall the photosynthetic capacity of A. donax is high compared to other C3 species, and comparable to C4 bioenergy grasses.