The Absorption and Reflection Spectra of Leaves, Chloroplast Suspensions, and Chloroplast Fragments as Measured in an Ulbricht Sphere

Rabideau, Glenn S.; French, C. S.; Holt, A. S.

doi:10.2307/2437271

Cited by 62 publications

(18 citation statements)

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“…This scattering is wavelength dependent and is greatest at wavelengths where the absorption is lowest (Ruhle and Wild, 1979); using leaves with a low Chl content, Ruhle and Wild (1979) found a path length increase of up to six times due to scattering. Since leaves absorb only weakly at approximately 820 nm (Rabideau et al, 1946), the absorbance changes due to P-700 obtained at these wavelengths are therefore many times larger than expected.…”

Section: P-700 In Leavesmentioning

confidence: 78%

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Harbinson

Hedley

1993

Plant Physiol.

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Following dark adaptation, the response to irradiance of chlorophyll (Chl) fluorescence, the light-induced absorbance change around 820 nm (to measure reaction center Chl of photosystem I[PSI] P-700 oxidation), and COz fixation were examined in pea (Pisum sativum 1.) leaves under a range of conditions. Initially, P-700 oxidation is restricted by a lack of regeneration of PSI electron acceptors, and the increase of oxidized P-700 (P-700+) that occurs during approximately the first 60 s of irradiation is largely independent of the resistance to electron flow between the two photosystems. Under these conditions, the quantum efficiency for linear electron flow is directly positively related to P-700+ accumulation, which is in contrast to the direct negative correlation that is the most frequently reported relationship between P-700+ accumulation and the quantum efficiency for linear electron flow.

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Section: P-700 In Leavesmentioning

confidence: 78%

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Harbinson

Hedley

1993

Plant Physiol.

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“…At the conclusion of light dependence measurements, two discs of interveinal leaf tissue were removed for absorptance determinations using an Ulbricht sphere (6,21). Light entering the sphere originated from a 2.5 kw xenon arc lamp and passed through a red (RG-645) filter.…”

Section: Methodsmentioning

confidence: 99%

Effects of Powdery Mildew Infection on the Efficiency of CO₂ Fixation and Light Utilization by Sugar Beet Leaves

Gordon¹,

Duniway²

1982

Plant Physiol.

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Sugar beet leaves (Beta vulgaris L.) infected with powdery mildew (Erysiphe polygoni D.C.) show declining rates of net photosynthesis as the disease develops; relative to healthy controls, reductions of 35, 70, and 75% were observed at 9, 16, and 22 days after inoculation, respectively. A leaf gas exchange procedure in which an air stream flowed through the leaf showed that mesophyDl conductance declined in parallel with photosynthesis in mildew-infected leaves. Viscous flow conductance of diseased leaves also declined over the same period suggesting that stomatal aperture was reduced. From the magnitude and time course of disease effects on stomatal aperture and mesophyli conductance, it appears that the effects at the mesophyli level were primarily responsible for mediating the decline in net photosynthesis. Changes in mesophyli conductance were closely correlated with reduced activity of ribulose-1,5-bisphosphate carboxylase on a leaf area basis. This decrease could be attributed to a reduction in the concentration of the enzyme, a reduction which was greater than the reduction in total soluble protein. The quantum efficiency of light use was also decreased by the disease. Mildew-infected leaves had quantum yields that were reduced, relative to healthy leaves, by 17 and 22% at 14 and 18 days after inoculation, respectively.The powdery mildews are obligate fungal parasites which infect a number of economically important crops. The fungus grows superficially on infected leaves with invasive growth by subtending haustoria being restricted to the epidermal cells. Leaves infected with powdery mildews commonly show decreased rates of net photosynthesis (1,3,6,10,18). To evaluate the factors potentially limiting photosynthesis in diseased leaves requires measurements of stomatal and mesophyll conductances to CO2 uptake. These are ordinarily obtained by calculations based on rates of diffusive CO2 and water vapor exchange. Mildew on the leafsurface renders this approach somewhat problematical because the mycelium contributes an unknown amount of water vapor to the transpiration stream. However, we used an inoculation procedure which restricted mildew development to the adaxial surface of sugar beet leaves (6). This allowed us to use gas exchange data from the uninfected abaxial surface to show that, in spite of the mildew on the adaxial surface, rates of water vapor loss from the adaxial surface could still be used to give reasonably accurate values of adaxial stomatal condutance (6). We were therefore able to deduce the mesophyll component of conductance to CO2 in mildewed leaves. The results revealed mesophyll conductance to be of primary importance in limiting light-saturated rates of net photosynthesis in mildew-infected sugar beet leaves (6).In the present study we have used a flow through the leaf procedure to investigate the effects of powdery mildew on photosynthesis at the mesophyll level in sugar beet leaves. This technique provides a measure of mesophyll conductance which is not influenced by stoma...

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“…The gas analyzer used for our experiments was a Horiba Instruments IR CO2 analyzer (model VIA-500R), and light for both photosynthetic and absorptance measurement was provided by a 2.5-kw short arc xenon lamp (Christie Electric Corp.). Light absorptance values (400-700 nm) were determined for the same leaves used in photosynthetic measurements using an integrating sphere (16) (24).…”

mentioning

confidence: 99%

Differential Light Responses of Photosynthesis by Triazine-resistant and Triazine-susceptible Senecio vulgaris Biotypes

Holt¹,

Stemler²,

Radosevich³

1981

Plant Physiol.

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The Absorption and Reflection Spectra of Leaves, Chloroplast Suspensions, and Chloroplast Fragments as Measured in an Ulbricht Sphere

Cited by 62 publications

References 0 publications

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Effects of Powdery Mildew Infection on the Efficiency of CO₂ Fixation and Light Utilization by Sugar Beet Leaves

Differential Light Responses of Photosynthesis by Triazine-resistant and Triazine-susceptible Senecio vulgaris Biotypes

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The Absorption and Reflection Spectra of Leaves, Chloroplast Suspensions, and Chloroplast Fragments as Measured in an Ulbricht Sphere

Cited by 62 publications

References 0 publications

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Effects of Powdery Mildew Infection on the Efficiency of CO2 Fixation and Light Utilization by Sugar Beet Leaves

Differential Light Responses of Photosynthesis by Triazine-resistant and Triazine-susceptible Senecio vulgaris Biotypes

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Effects of Powdery Mildew Infection on the Efficiency of CO₂ Fixation and Light Utilization by Sugar Beet Leaves