The Effect of Enhanced CO 2 Levels andd Variable Light intensities on Net photosynthesis in Competing Mountain Trees

1976 ◽  
Vol 95 (2) ◽  
pp. 446 ◽  
Author(s):  
William Bryan ◽  
Robert Wright
Keyword(s):  
Net Photosynthesis ◽  
Light Intensities ◽  
Variable Light

Carbon dioxide transfer resistance as a factor in shade tolerance of tree seedlings

1970 ◽  
Vol 48 (3) ◽  
pp. 453-456 ◽  
Author(s):  
J. E. Wuenscher ◽  
T. T. Kozlowski
Keyword(s):  
Carbon Dioxide ◽  
Acer Saccharum ◽  
Net Photosynthesis ◽  
Tree Seedlings ◽  
Transfer Resistance ◽  
Quercus Velutina ◽  
Light Intensities ◽  
Quercus Species ◽  
Highly Correlated ◽  
Resistance Rates

Net photosynthesis and transpiration rates of single leaves of Quercus velutina Lam., Q. macrocarpa Michx. var. olivaeformis, and Acer saccharum Marsh. were measured at light intensities of 0.03 to 0.24 cal cm−2 min−1 (400–700 mμ). Resistance to water vapor and carbon dioxide transfer were calculated. Net photosynthesis of the Quercus species was not light saturated until light intensity was increased sufficiently to induce complete stomatal opening, indicating possible limitation of CO2 uptake at low light intensities by high CO2 transfer resistance. Rates of light-saturated net photosynthesis of all three species were highly correlated with CO2 transfer resistance.

Growth kinetics of Marquis wheat. IV. Temperature dependence

1973 ◽  
Vol 51 (4) ◽  
pp. 729-736 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Light Intensity ◽  
Plant Growth ◽  
Net Photosynthesis ◽  
Absolute Maximum ◽  
Temperature Optimum ◽  
Differential Growth ◽  
Low Light ◽  
Growth Coefficient ◽  
Light Intensities ◽  
Kinetics Of

Earlier described data from this laboratory were subjected to primary growth analysis. The plants had been grown in constant conditions of light intensity (200 to 2500 ft-c) and temperature (10° to 30 °C) at five different settings each. Multiple temperature optima were revealed and interpreted. The computed maximum plant growth coefficient was highest in value at 25 °C (plant kmL = 0.44 day−1) and secondarily so at 15 °C, but at the experimental light intensities the plant growth coefficient was maximal at 15 °C. The higher temperature optimum was characteristic of roots and "stems" (stem plus leaf sheaths) whose growth coefficients displayed a prominent peak at 25 °C (root kmL ~ 0.8 day−1, "stem" kmL = 0.4 day−1). This optimum was shifted downward with decreasing light intensity until temperature insensitivity was attained at low light intensity. The low-temperature optimum at 15 °C was principally displayed by leaf blades (lamina kmL = 0.47 day−1) whose computed maximum growth coefficient also showed a secondary maximum at 25°, but the 15 °C peak was the only one evident at low light intensities. It was tentatively concluded that the 25 °C temperature optimum was that of net translocation, and that the 15 °C temperature optimum was that of net photosynthesis in which photosynthesis was primarily balanced by photorespiration in wheat. The differential growth of the organs represented their relative sink strengths for attracting growth substrate, as dependent on light intensity and temperature. The availability of photosynthate was considered to be the dominating factor in the kinetics of growth free from inorganic limitations. When there was very little photosynthate the tissues benefited from translocation on a "first come first serve" basis. The high values of kmL pushed the absolute maximum plant growth coefficient, kM, of Marquis wheat toward 0.5 or 50% per day, and the basis of the advantage over previous approximations must be elucidated by further experiments. The computed relative efficiency of the use of photosynthate for growth was temperature dependent, but its value at optimum temperature was similar to previous estimates.

Marine Phytoplankton Photosynthesis as a Function of Light Intensity: A Comparison of Methods

1964 ◽  
Vol 21 (1) ◽  
pp. 159-181 ◽  
Author(s):  
C. D. McAllister ◽  
N. Shah ◽  
J. D. H. Strickland
Keyword(s):  
Cell Division ◽  
Skeletonema Costatum ◽  
Algal Growth ◽  
Net Photosynthesis ◽  
Growth Conditions ◽  
Marine Phytoplankton ◽  
Fluorescent Light ◽  
Particulate Carbon ◽  
Gross Photosynthesis ◽  
Light Intensities

An apparatus is described in which the constant for exponential algal growth has been determined as a function of light at controlled temperature. Studies were made of bacteria-free cultures of Skeletonema costatum and Dunaliella tertiolecta grown at the optimum temperature for cell division in media with and without adequate nitrate and phosphate. Less complete studies were made of the behaviour of Monochrysis lutheri and Amphidinium carteri. In all experiments the growth constants were determined at known light intensities, expressed in the energy units, langlies/minute, using light of a known spectral distribution similar to sunlight shining through a few metres of coastal sea water.Growth constants were determined for the following processes: increase of cellular carbon, chlorophylls a, b or c, carotenoids, cell numbers and photosynthesis measured both by oxygen evolution (net and gross) and by the uptake of C-14 labelled carbonate.The rate of maximum photosynthesis occurred when the illumination reached about 0.1 ly/min and little or no light inhibition occurred when the intensity was increased to as high as 0.4 ly/min. Respiration was about 10% of maximum gross photosynthesis. This fraction increased when cells were nitrogen deficient but decreased in phosphate deficient cultures because a phosphate shortage inhibited respiration more severely than photosynthesis.Gross photosynthesis at low light intensities was proportional to the total number of molecules of all plant pigments added together, irrespective of species or of culturing conditions. By contrast, the rate of maximum gross photosynthesis was poorly related to pigment composition, the best correspondence being with the amount of chlorophyll a in the cultures.The uptake rate of C-14 varied with time. There was an apparent "leakage" of labelled organic matter which eventually reached a near-equilibrium with 14CO2 uptake, after which the C-14 method measured the production of particulate carbon but not necessarily net or gross photosynthesis. The rate of particulate carbon production was the same as that of cell division but about 40% less than net photosynthesis in cultures of Skeletonema. Agreement between C-14 rates and net photosynthesis was better in cool-white fluorescent light than in the imitation submarine sunlight used in this work. At high light intensities there was apparently no excretion from Dunaliella "shade" cells but when these became changed to "sun" cells they behaved more like Skeletonema.Various observations are recorded of the effect of growth conditions on cell composition, especially with regard to pigments.The relatively low C-14 rates found with Skeletonema costatum may be explicable in part by an abnormally low counting efficiency for this species even when present as a "weightless" source but the problem requires further study.

scholarly journals Canopy Photosynthesis and Time-of-day Application of Supplemental Light

HortScience ◽  
2009 ◽  
Vol 44 (5) ◽  
pp. 1284-1290 ◽  
Author(s):  
Jakob Markvart ◽  
Eva Rosenqvist ◽  
Helle Sørensen ◽  
Carl-Otto Ottosen ◽  
Jesper M. Aaslyng
Keyword(s):  
Dark Respiration ◽  
High Growth ◽  
Net Photosynthesis ◽  
Time Of Day ◽  
Photon Flux ◽  
Carbon Gain ◽  
Climate Control ◽  
Low Light ◽  
Light Intensities ◽  
Supplemental Lighting

There is increasing use of electricity for supplemental lighting in the northern European greenhouse industry. One reason for this may be to secure a high growth rate during low-light periods by an attempt to increase net photosynthesis. We wanted to clarify which period of the day resulted in the best use of a 5-h supplemental light period for photosynthesis and growth. The periods tested were supplemental light during the night, day, morning, and evening. The experiments were carried out in daylight climate chambers measuring canopy gas exchange. The air temperature was 25 °C and the CO2 level ≈900 ppm. Vegetative chrysanthemum was used, because this species responds quickly to change in light level. The leaf areas of the plant canopies were nondestructively measured each week during the 4-week experimental period. The fact that the quantum yield of photosynthesis is greater at low than at high light intensities favors the use of supplemental light during the dark period, but growth measured as dry weight of the treated plants at the end of the experiments was not significantly different given identical light integrals of the treatments. However, one experiment indicated that increased time with dark hours during day and night (24 h) might decrease net photosynthesis. The assimilation per unit leaf area was approximately the same during times of sunlight through a diffusing screen at 100 μmol·m−2·s−1 of photosynthetic photon flux (PPF) as during times of supplemental (direct) light application at PPF of 200 μmol·m−2·s−1 by high-pressure sodium lamps. We conclude that during the winter and periods of low light intensities, the daily carbon gain does not depend on the time of supplemental light application, but is linked to the total light integral. However, extended time with dark hours during day and night (24 h) might be a disadvantage because of longer periods with dark respiration and subsequent loss of carbon. Our results indicate that during times of low light conditions, it is not necessary to include factors such as the timing of supplemental lighting application to achieve higher net photosynthesis in climate control strategies.

scholarly journals Growth reactions of carnation, measured by net photosynthesis, on different air contents of the soil.

1970 ◽  
Vol 18 (3) ◽  
pp. 149-157
Author(s):  
A.L.M. Van Wijk ◽  
J. Buitendijk
Keyword(s):  
Light Intensity ◽  
Dry Matter ◽  
Dianthus Caryophyllus ◽  
Net Photosynthesis ◽  
Constant Level ◽  
Fresh Matter ◽  
Soil Air ◽  
Air Content ◽  
Light Intensities ◽  
Matter Production

In pot experiments, Dianthus caryophyllus plants grown for 2 1/2 months at soil-air levels of 20, 10 or 5% (v/v) produced approx. equal amounts of dry matter, but fresh-matter production at 5 and 10% soil air was 13 and 2% lower than at 20% soil air. The effect of aeration on growth (photosynthesis) increased with increasing light intensity. Decreasing content of soil air from 20, 10 and 5% to 5 and 2.5% respectively was accompanied by an immediate reduction of photosynthesis to a fairly constant level. This reduction increased with increasing light intensity. An increase in soil air from 2.5 to 20, 10 or 5% gave a recovery of photosynthesis which at the two lowest light intensities was complete within 1-3 days when the period of low air content was not >14 days. At the highest light intensity the recovery of photosynthesis was slower. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Photosynthesis in Artificial Communities of Wheat, Lucerne, and Subterranean Clover Plants

1967 ◽  
Vol 20 (3) ◽  
pp. 623 ◽  
Author(s):  
RW King ◽  
LT Evans
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Dark Respiration ◽  
Subterranean Clover ◽  
Net Photosynthesis ◽  
Area Index ◽  
Light Intensities

The relation between leaf area index (L.A.I.) and rates of net photosynthesis at three light intensities, and of dark respiration, was examined throughout the course of growth of artificial communities of wheat and lucerne at 20�C, and of subterranean clover at 25� /20�C.

scholarly journals Trinexapac-ethyl Restricts Shoot Growth and Improves Quality of `Diamond' Zoysiagrass Under Shade

HortScience ◽  
1998 ◽  
Vol 33 (6) ◽  
pp. 1019-1022 ◽  
Author(s):  
Y.L. Qian ◽  
M.C. Engelke ◽  
M.J.V. Foster ◽  
S. Reynolds
Keyword(s):  
Shoot Growth ◽  
Physiological Responses ◽  
Acid Ethyl Ester ◽  
Energy Depletion ◽  
Zoysia Matrella ◽  
Turf Quality ◽  
Light Intensities ◽  
Variable Light ◽  
Tiller Density

Turfgrass is grown under extremely variable light intensities. This presents difficult management problems, and methods are needed to improve turf performance under variable shade conditions. Two experiments were conducted to determine the influence of trinexapac-ethyl (TE) on turf performance and physiological responses of `Diamond' zoysiagrass [Zoysia matrella (L.) Merr.] under several light intensities. In a polyethylene-roofed greenhouse, `Diamond' was sodded in 12 wooden boxes (1.2 × 1.2 × 0.16 m) (Expt. 1) and 18 fiber containers (55 × 38 × 12 cm) (Expt. 2). Treatments applied to boxes or containers included three levels of shade (40%, 75%, and 88%) with and without multiple TE applications at 48 g·ha-1 of active ingredient. Without TE treatment, vertical shoot growth increased linearly with increasing shade levels. Excessive shoot growth under 75% and 88% shade exacerbated energy depletion, as evidenced by the 45% and 67% lower rhizome mass and the 37% and 65% lower total nonstructural carbohydrate content (TNC), respectively, compared with turf under 40% shade. Trinexapac-ethyl reduced excessive vertical shoot growth and increased rhizome mass and TNC. Mean turf quality was increased by 0.7 and 1.4 units for turf receiving multiple TE applications under 75% and 88% shade, respectively. Trinexapac-ethyl did not increase turf quality or TNC under 40% shade. Canopy photosynthetic rate (Pn) was not affected 4 weeks after the initial TE treatment under any shade level. However, 34 weeks after the initial TE treatment a 50% higher Pn was observed for turf treated with TE under 88% shade, possibly because of higher tiller density. Repeated TE application increased turf quality and provided more favorable physiological responses (such as TNC and Pn) under 75% and 88% shade, where conditions favored vertical shoot growth. However, little or no improvement in turf quality was observed under 40% shade, where conditions favored slow vertical shoot growth. Chemical name used: 4-(cyclopropyl-α-hydroxy-methylene)-3,5-dioxo-cyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl).

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