scholarly journals Effect of Light Intensity and Leaf Temperature on Photosynthesis and Transpiration in Wheat and Sorghum

1970 ◽  
Vol 23 (4) ◽  
pp. 775 ◽  
Author(s):  
RW Downes
Keyword(s):  
Carbon Dioxide ◽  
Water Use ◽  
Carbon Dioxide Concentration ◽  
Leaf Temperature ◽  
High Light ◽  
Intercellular Spaces ◽  
Concentration Difference ◽  
Light Levels ◽  
Light Intensities ◽  
Water Vapour Concentration

Wheat stomata offered less resistance to water and carbon dioxide diffusion than sorghum stomata at light intensities of 0�06 and 0�26 cal cm-2 min-i (400-700 nm) but resistances were comparable at 0�46 cal cm-2 min-i. Consequently, transpiration rates were higher in wheat than in sorghum, except at the high light levels, in leaf chamber experiments described here. Rates of photosynthesis were higher in sorghum than in wheat, with the greatest difference at high light levels. This resulted in a greater efficiency of dry matter production relative to water use in sorghum. Transpiration rate increased with increased temperature in both species. Photosynthesis was independent of temperature in wheat, and in sorghum under low light conditions, but otherwise photosynthesis increased with temperature in sorghum. In both species, efficiency of water use decreased as temperature increased at all light intensities. Water vapour concentration difference between the intercellular spaces and the air was comparable in wheat and sorghum and increased with temperature. The carbon dioxide concentration difference between air and intercellular spaces was substantially greater in sorghum than in wheat and increased with leaf temperature. Maximum values were obtained at the intermediate light level in sorghum.

Growth kinetics of Marquis wheat. II. Carbon dioxide dependence

1972 ◽  
Vol 50 (4) ◽  
pp. 883-889 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Carbon Dioxide ◽  
Light Intensity ◽  
Carbon Dioxide Concentration ◽  
Dry Weight ◽  
Maximum Growth ◽  
Carbon Dioxide Enrichment ◽  
Low Light ◽  
Growth Coefficient ◽  
Light Intensities ◽  
Wide Range

Marquis wheat was grown in growth rooms with four different concentrations of carbon dioxide and four to seven different intensities of light in a 16-h photoperiod at 25 °C. Growth was expressed quantitatively as the pseudo-first-order rate coefficient. Carbon dioxide stimulated growth, but the effect was greater the lower the light intensity in opposition to the known effect on photosynthesis. Carbon dioxide and light, in effect, did not influence the "rate" of growth of wheat additively but, rather, mutually compensated over a wide range. The growth coefficient of the roots was a little less than that of the shoots at all carbon dioxide concentrations and light intensities, probably owing to the cost of translocation. However, root growth benefited most from carbon dioxide enrichment at low light intensities. At intermediate light intensity there appeared to be a carbon dioxide concentration optimal for shoot growth. Carbon dioxide enrichment did not influence the maximum growth coefficient of Marquis wheat with respect to light intensity. The light-using efficiency of growth, calculated for vanishingly low light intensity at which it is maximal, was maximal for shoots at 1300 ppm CO2 but that for laminal area and root dry weight increased with CO2 to 2200 ppm at which the value for "leaves" was nearly fourfold that for roots. Unlike photosynthesis, the stimulation of growth by raised CO2 concentration was accomplished by increased efficiency of, and not capacity for, the net photosynthetic use of light.

scholarly journals USE OF A GLASS ELECTRODE FOR MEASURING RAPID CHANGES IN PHOTOSYNTHETIC RATES

1954 ◽  
Vol 37 (6) ◽  
pp. 753-774 ◽  
Author(s):  
Jerome L. Rosenberg
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Photosynthetic Rate ◽  
Carbon Dioxide Concentration ◽  
Glass Electrode ◽  
High Light ◽  
Gas Streams ◽  
Partial Pressures ◽  
Rapid Changes ◽  
Concentration Changes

1. A continuously recording glass electrode apparatus has been described for measuring carbon dioxide concentration changes in solution. The limits of applicability of the apparatus have been analyzed. 2. The glass electrode apparatus has been used for the measurement of transient rates of photosynthesis by algal suspensions. 3. The decline of the photosynthetic rate in high light at carbon dioxide partial pressures less than 0.5 per cent atmosphere, observed in the glass electrode apparatus, has been confirmed by steady state experiments in which flowing gas streams were analyzed.

scholarly journals CARBON DIOXIDE BALANCE AT HIGH LIGHT INTENSITIES

1935 ◽  
Vol 10 (1) ◽  
pp. 93-114 ◽  
Author(s):  
Elmer S. Miller ◽  
G. O. Burr
Keyword(s):  
Carbon Dioxide ◽  
High Light ◽  
Light Intensities ◽  
Carbon Dioxide Balance

Intraspecific variation in photosynthetic traits of Populus trichocarpa

1993 ◽  
Vol 71 (10) ◽  
pp. 1304-1311 ◽  
Author(s):  
J. M. Dunlap ◽  
J. H. Braatne ◽  
T. M. Hinckley ◽  
R. F. Stettler
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Populus Trichocarpa ◽  
High Light ◽  
Black Cottonwood ◽  
Photosynthetic Rates ◽  
Light Levels ◽  
Lower Elevation ◽  
Use Efficiency ◽  
River Valleys

Three experiments were conducted to evaluate net photosynthesis in black cottonwood (Populus trichocarpa Torrey & Gray) from mesic and xeric regions of Washington. In 1986, six clones each from the lower Nisqually (mesic) and Yakima (xeric) river valleys and growing in a common garden were measured for their photosynthetic rates. On 2 clear days in summer, Yakima clones had significantly (p ≤ 0.10) higher rates (means: 32 and 25μmol CO2 m−2 s−1) than Nisqually clones (means: 25 and 22μmol CO2 m−2 s−1). The next year, cuttings from these clones were potted, grown separately for 2 months in a maritime (Puyallup, Wash.) and a continental climate (Wenatchee, Wash.), and then transferred to growth chambers in Seattle, Wash. Photosynthetic rates were determined at four light levels (200, 500, 800, and 1500 μmol m−2 s−1) and two temperatures (24 and 32 °C). Yakima plants had significantly (p ≤ 0.05) higher rates at high light (20μmol CO2 m−2 s−1) and also at moderate light in high temperature than Nisqually plants (16 μmol CO2 m−2 s−1 in high light). Significant acclimation (p ≤ 0.01) was also revealed: at the two moderate light levels in high temperatures the Wenatchee-grown plants, regardless of source, had higher rates than those grown at Puyallup. In 1991, eight clones from the lower elevation, xeric region of the Yakima and eight from the upper elevation, mesic region were selected in a Puyallup stoolbed, and their photosynthesis and water-use efficiency were measured on a clear summer day. Lower elevation plants had a higher photosynthetic rate than those from the upper elevations along the Yakima; values were similar to those of 1986. The pattern for water-use efficiency was reversed; values were 56 μmol CO2/mol H2O for the lower and 84 μmol CO2/mol H2O for the upper Yakima plants. These three experiments provide evidence for significant genetic variation in photosynthetic processes both between and within river valleys. Key words: Populus trichocarpa, black cottonwood, poplar, photosynthesis, water-use efficiency, adaptation.

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