Effects of Light Intensity and Temperature on Photosynthesis and Respiration of Two East Antarctic Mosses, Bryum argenteum and Bryum antarcticum

1970 ◽  
Vol 73 (3) ◽  
pp. 544 ◽  
Author(s):  
James R. Rastorfer
Keyword(s):  
Light Intensity ◽  
Bryum Argenteum ◽  
Photosynthesis And Respiration ◽  
Antarctic Mosses

Patterns of lichen photosynthesis and respiration following prolonged frozen storage

1978 ◽  
Vol 56 (17) ◽  
pp. 2119-2123 ◽  
Author(s):  
Douglas W. Larson
Keyword(s):  
Light Intensity ◽  
Low Temperatures ◽  
Physiological Activity ◽  
Frozen Storage ◽  
Experimental Systems ◽  
Long Term Storage ◽  
Photosynthesis And Respiration ◽  
Term Storage ◽  
Respiratory Responses

The effect of prolonged frozen storage on patterns of photosynthesis and respiration in the lichen Alectoria ochroleuca (Hoffm.) Massal. has been examined. The results indicate that this plant not only survives long-term exposure to low temperatures but also that its basic photosynthetic and respiratory responses to temperature, light intensity, and thallus moisture content are altered very little by long-term storage at −60 °C. This maintenance not only of absolute viability but also of the more subtle patterns of physiological activity suggests that such storage may be used to hold lichen material for use in multivariate experimental systems which require replicates having identical field pretreatment.

scholarly journals Photosynthesis and Respiration by the Flag Leaf and Components of the Ear During Grain Development In Wheat

1970 ◽  
Vol 23 (2) ◽  
pp. 245 ◽  
Author(s):  
LT Evans ◽  
HM Rawson
Keyword(s):  
Light Intensity ◽  
Dark Respiration ◽  
Flag Leaf ◽  
Gas Analysis ◽  
Constant Light ◽  
Grain Development ◽  
Flag Leaves ◽  
Photosynthesis And Respiration

Rates of photosynthesis and dark respiration of the ears and flag leaves of three varieties of wheat grown at 21 DC under a constant light intensity of 3200 f.c. were measured by infrared gas analysis twice weekly throughout the period of grain development. Measurements were made on both the intact ears and the separated grains and ear structures, in air and in a mixture of nitrogen plus 320 p.p.m. C02. Dry weights of the grains, ears, and main stems were also determined.

Efficiency of solar energy conversion as a function of light intensity

2008 ◽  
Vol 80 (10) ◽  
pp. 2069-2077
Author(s):  
Sergei Varfolomeev
Keyword(s):  
Solar Energy ◽  
Light Intensity ◽  
Energy Conversion ◽  
Solar Energy Conversion ◽  
Maximum Efficiency ◽  
Light Illumination ◽  
Photosynthetic System ◽  
System Parameters ◽  
Photosynthetic Antenna ◽  
Photosynthesis And Respiration

The kinetic model has been developed for disserting the efficiency of solar energy conversion as a function of light intensity. A comparison of theory with experimental results shows that the model provides a satisfactory agreement. We have estimated the essential parameters of photosynthetic systems (the size of the photosynthetic antenna, the rate of electron transport, the correlation between photosynthesis and respiration) that are responsible for reaching the maximum efficiency at "one sun" and "one hundred suns" light illumination intensities. Recommendations for the improvement of photosynthetic system parameters using genetic engineering methods are also provided.

Bathymetric and seasonal changes in photosynthesis and respiration of the phototrophic sponge Phyllospongia lamellosa in comparison with respiration by the heterotrophic sponge Ianthella basta on Davies Reef, Great Barrier Reef

1997 ◽  
Vol 48 (7) ◽  
pp. 589 ◽  
Author(s):  
Anthony C. Cheshire ◽  
Clive R. Wilkinson ◽  
Stephanie Seddon ◽  
Grant Westphalen
Keyword(s):  
Light Intensity ◽  
Great Barrier Reef ◽  
Respiration Rate ◽  
Seasonal Changes ◽  
Shallow Waters ◽  
Barrier Reef ◽  
Fresh Weight ◽  
Respiration Rates ◽  
Reduced Light ◽  
Photosynthesis And Respiration

The phototrophic sponge Phyllospongia lamellosa is found to depths of 30 m on Davies Reef. Studies of the photophysiology show that this corresponds to the depth at which the sponge–symbiont system can meet 80% of its daily respiratory carbon needs photosynthetically. Net 24-h production was constant to a depth of 20 m (20 µmol O2 g-1 fresh weight day -1 ) and then decreased to compensatory levels at 25 m. The maintenance of net 24-h production to a depth of 20 m was characterized by reductions in the sub-saturating light intensity (Ik ), indicating increased efficiency of light usage at depth. At depths greater than 20 m the changes in Ik could not compensate for the reduced light intensity. The respiration rate of Phyllospongia (3–5 µmol O2 g-1 fresh weight h-1 ) was significantly greater than that of the heterotrophic sponge Ianthella (2.0–3.6 µmol O2 g-1 fresh weight h-1 ) to an extent that depended on season and location. Respiration rates for both species changed similarly between seasons, being higher in summer. There was no evidence for increased respiration rates in shallower water (<10 m), suggesting that this is not a cause for the reduced occurrence of Phyllospongia in shallow waters.

The effect of some environmental factors on the growth of young aspen trees (Populus tremuloides) in controlled environments

1971 ◽  
Vol 49 (8) ◽  
pp. 1443-1453 ◽  
Author(s):  
G. C. Bate ◽  
D. T. Canvin
Keyword(s):  
Light Intensity ◽  
Photosynthetic Rate ◽  
Populus Tremuloides ◽  
Dark Respiration ◽  
Continuous Light ◽  
Carbon Gain ◽  
Fluorescent Light ◽  
Controlled Environment ◽  
Rate Of Photosynthesis ◽  
Photosynthesis And Respiration

Several populations (each of 32 trees) of young aspen trees (Populus tremuloides Michx) were allowed to break from dormancy in controlled environment cabinets. The rate of photosynthesis and dark respiration and the rate of carbon gain (as difference between photosynthesis and respiration) of the population as affected by photoperiod duration, light intensity, and day/night temperatures was determined by measuring the CO2 exchange of the whole population using the controlled environment cabinet as the plant chamber.The rates of photosynthesis of the plants were similar during both 12- or 18-h photoperiods. The rates of respiration during the corresponding night periods were also similar. In continuous light the photosynthetic rate remained unchanged if growth (expansion of new leaves) was rapid. During periods of slower growth, the photosynthetic rate in continuous light was reduced. In spite of this reduction in the rate of photosynthesis, carbon gain was still greatest under continuous light.In the day/night temperature study, the largest gains in carbon per day by the aspen trees were obtained at day/night temperatures of 15/10 °C or 15/15 °C. Higher day or night temperatures resulted in decreased rates of carbon gain.Increased light intensity from fluorescent lamps resulted in increased rates of photosynthesis. Addition of incandescent light to the fluorescent light resulted, in almost all cases, in decreased rates of photosynthesis. This may, in part, be due to effects on leaf temperature.Photosynthesis of the populations was usually maximal at the beginning of the photoperiod and decreased steadily during the photoperiod. The rate of decrease was directly related to the rate of photosynthesis at the beginning of the photoperiod.Both photosynthesis and respiration were affected by temperature and light but no clear relationship existed between the rate of CO2 exchange during the photoperiod and that during the nyctoperiod following.

La respiration et la photosynthèse de frênes qui poussent dans des conditions différentes

1973 ◽  
Vol 36 ◽  
Author(s):  
N. Lust
Keyword(s):  
Light Intensity ◽  
Chlorophyll Content ◽  
Leaf Surface ◽  
Physiological Characteristics ◽  
Different Ages ◽  
Shade Leaves ◽  
Sun Leaves ◽  
Photosynthesis And Respiration

Respiration and photosynthesis of ashes, grown up under  different circumstances - Some physiological  characteristics have been researched on ashes of different ages and height  and grown up under different Iight circumstances :     - the respiration pro unit of leaf surface and pro unit of weight.     - the photosynthesis pro unit of leaf surface and pro unit of weight.     - the apparent photosynthesis    - the relation photosynthesis-respiration    - the relation photosynthesis-chlorophyll content.     Besides the influence of the light characteristics of the leaves, the  research proves also the influence of age, height and provenance on the  amount of photosynthesis and respiration.    The respiration and photosynthesis pro unit of leaf surface is higher with  sun leaves as with shade leaves.     With ashes, grown up at the same level of light intensity, not only the  relation photosynthesis-respiration, but also the apparent photosynthesis is  higher with shade leaves as with sun leaves.

Fine structure of the retina of the giant scallop, Placopecten magellanicus

1984 ◽  
Vol 42 ◽  
pp. 312-313
Author(s):  
C.V.L. Powell
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Light Intensity ◽  
Scanning Electron Microscope ◽  
Eye Development ◽  
Preliminary Observation ◽  
Columnar Epithelium ◽  
Placopecten Magellanicus ◽  
Environmental Light ◽  
Scanning Electron

The overall fine structure of the eye in Placopecten is similar to that of other scallops. The optic tentacle consists of an outer columnar epithelium which is modified into a pigmented iris and a cornea (Fig. 1). This capsule encloses the cellular lens, retina, reflecting argentea and the pigmented tapetum. The retina is divided into two parts (Fig. 2). The distal retina functions in the detection of movement and the proximal retina monitors environmental light intensity. The purpose of the present study is to describe the ultrastructure of the retina as a preliminary observation on eye development. This is also the first known presentation of scanning electron microscope studies of the eye of the scallop.

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