scholarly journals Photosynthesis of Tropical Pasture Plants III. Leaf Age

1971 ◽  
Vol 24 (4) ◽  
pp. 1077 ◽  
Author(s):  
MM Ludlow ◽  
GL Wilson
Keyword(s):  
Dark Respiration ◽  
Leaf Age ◽  
Gas Analysis ◽  
Controlled Environment ◽  
Tropical Pasture ◽  
Optimum Conditions ◽  
Dark Respiration Rate ◽  
Leaf Ontogeny ◽  
Analysis System ◽  
Pasture Plants

Grass and legume plants were grown under near-optimum conditions in controlled-environment cabinets. Changes in net photosynthetic rate, dark respiration rate, and carbon dioxide transfer resistances during leaf ontogeny, and variability between leaves on grass tillers and legume runners were studied under controlled conditions in an open gas analysis system.

scholarly journals Photosynthesis of Tropical Pasture Plants II. Temperature and Illuminance History

1971 ◽  
Vol 24 (4) ◽  
pp. 1065 ◽  
Author(s):  
MM Ludlow ◽  
GL Wilson
Keyword(s):  
Carbon Dioxide ◽  
Water Vapour ◽  
Gas Analysis ◽  
Controlled Environment ◽  
Tropical Pasture ◽  
Two Temperatures ◽  
Analysis System ◽  
Pasture Plants

Grasses and legumes were grown at two temperatures in controlled-environment rooms and at three illuminances (obtained by shading) in a glasshouse. Carbon dioxide and water vapour exchange of leaves were measured in an open gas analysis system.

scholarly journals Photosynthesis of Tropical Pasture Plants I. Illuminance, Carbon Dioxide Concentration, Leaf Temperature, and Leaf-Air Vapour Pressure Difference

1971 ◽  
Vol 24 (3) ◽  
pp. 449 ◽  
Author(s):  
M M Ludlow ◽  
GL Wilson
Keyword(s):  
Carbon Dioxide ◽  
Vapour Pressure ◽  
Pressure Difference ◽  
Carbon Dioxide Concentration ◽  
Gas Analysis ◽  
Leaf Temperature ◽  
Tropical Pasture ◽  
Analysis System ◽  
Vapour Pressure Difference ◽  
Pasture Plants

Carbon dioxide and water vapour exchange of attached, young, fully expanded leaves of tropical pasture species were measured in an open gas analysis system. The influence of illuminance, carbon dioxide concentration, leaf temperature, and leaf-air vapour pressure difference on net photosynthetic rate and carbon dioxide transfer resistances was studied.

Application to Woody Plants of a Rapid Method for Determining Leaf CO2 Compensation Concentrations

1973 ◽  
Vol 3 (2) ◽  
pp. 237-242 ◽  
Author(s):  
D. I. Dickmann ◽  
D. H. Gjerstad
Keyword(s):  
Rapid Method ◽  
Woody Plants ◽  
Woody Species ◽  
Moisture Stress ◽  
Gas Analysis ◽  
Deionized Water ◽  
Controlled Environment ◽  
Gas Analyzer ◽  
Leaf Ontogeny ◽  
Infrared Gas Analyzer

A rapid method of determining CO2 compensation concentrations was developed and applied to woody plants. Whole leaves, needle fascicles, and twigs were excised, the cut ends inserted in a vial of deionized water, and the assembly placed in a Mylar bag. The bag was filled with air containing ca. 400 p.p.m. CO2. After 1 h in a growth chamber (24 °C, 3800 ft-c (40 660 lux)), the air was expelled from the bag through an infrared gas analyzer. Compensation concentrations determined by this method agreed with values obtained by using conventional closed-circuit gas analysis. The method was successfully applied to 14 gymnosperm and 55 angiosperm woody species and clones, including field-grown plants and rooted cuttings grown under controlled environment. Variation among species was small, compensation concentrations usually falling between 55 and 65 p.p.m. CO2, the range associated with C3 plants. The influence of temperature, moisture stress, and leaf ontogeny on leaf CO2 compensation also was studied.

The effect of climate on the photosynthesis of Picea mariana at the subarctic tree line. 1. Field measurements

1975 ◽  
Vol 53 (7) ◽  
pp. 604-620 ◽  
Author(s):  
T. Vowinckel ◽  
W. C. Oechel ◽  
W. G. Boll
Keyword(s):  
Picea Mariana ◽  
Dark Respiration ◽  
Environmental Parameters ◽  
Field Measurements ◽  
Dry Weight ◽  
Gas Analysis ◽  
Tree Line ◽  
Stevenson Screen ◽  
Analysis System ◽  
June July

Field measurements of the diurnal rates of photosynthesis of Picea mariana, the dominant tree species at the subarctic tree line, were made during the summers of 1972 and 1973 at Schefferville, Quebec (latitude 55° N). All relevant plant physiological and environmental parameters were also monitored. Photosynthesis was measured with an open gas analysis system with temperature-controlled cuvettes. Maximum daily rates were 2.0–3.5 mg CO2 g−1 dry weight h−1. Daily totals were between 15 and 30 mg CO2 g−1 dry weight. Temperature was unimportant in affecting daily photosynthesis totals during the summer months. The photosynthesis vs. needle temperature curve had an optimum of 15C. Dark respiration rates were 0.2–0.4 mg CO2 g−1 dry weight h−1 at 15C. The photosynthesis vs. light intensity curve was saturated at 0.8 ly min−1 (1.0 μE cm−2 s−1 PhAR.). As a result, heavy cloud cover considerably reduced daily photosynthesis. No seasonal variations in photosynthesis over June, July, and August were observed. No differences in maximum rates occurred between the three experimental sites. Needle temperatures within the cuvettes were 2–4C above air temperature under full sunlight (1.2 ly min−1). Needle temperatures under natural conditions were up to 7C above Stevenson screen temperatures and fluctuated rapidly with changes in turbulence.

Correlation Between the Rates of Foliar Dark Respiration and Net Photosynthesis in Some Tropical Dicot Weeds

Weed Science ◽  
1987 ◽  
Vol 35 (2) ◽  
pp. 141-144 ◽  
Author(s):  
G. Rajendrudu ◽  
J. S. Rama Prasad ◽  
V. S. Rama Das
Keyword(s):  
Respiration Rate ◽  
Dark Respiration ◽  
Leaf Age ◽  
Net Photosynthesis ◽  
Dark Respiration Rate ◽  
Weed Species ◽  
Unit Leaf ◽  
Positive Linear Correlation ◽  
Carbohydrate Levels ◽  
Photosynthetic Type

The rates of foliar dark respiration and net photosynthesis in attached leaves of 25 C3, C4, and C3-C4 intermediate dicotyledonous weed species were determined using the infrared gas analyzer. The ratio of dark respiration to photosynthesis per unit leaf area in attached leaves of each species was inversely proportional to leaf age. Highly significant, positive linear correlation was observed between the rates of foliar dark respiration and net photosynthetic CO2 uptake in dicot weeds irrespective of the photosynthetic type. The higher foliar dark respiration rate found in some of the weed species can be attributed in part to the higher carbohydrate levels as generated by a rapid photosynthetic CO2 assimilation. The significance of higher dark respiration rate in relation to carbon and energy economy of weeds is discussed.

scholarly journals A COMPARISON OF LEAF AND WHOLE PLANT NET PHOTOSYNTHESIS IN ALSTROEMERIA

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 576c-576
Author(s):  
E.D. Leonardos ◽  
M.J. Tsujita ◽  
B. Grodzinski ◽  
T.J. Blom
Keyword(s):  
Dark Respiration ◽  
Net Photosynthesis ◽  
Stomatal Resistance ◽  
Gas Analysis ◽  
Whole Plant ◽  
Plant Photosynthesis ◽  
Mutual Shading ◽  
Photosynthetic Responses ◽  
Analysis System ◽  
Two Stages

Gas exchange (net photosynthesis Pn, dark respiration, transpiration, and stomatal resistance) of `Jaqueline' Alstroemeria, grown in pots in a greenhouse, were measured. Measurements were made under laboratory conditions using an open-flow infrared gas analysis system for leaf studies, and a semi-closed computer controlled whole plant photosynthesis system for whole plant studies. Apical fully expanded leaves on non-flowering and flowering (at two stages) shoots had similar photosynthetic responses in respect to photosynthetically active radiation (PAR) and to CO2 concentration. Light saturation occurred at 600 umol/m2/s PAR with maximum leaf Pn rates ranging from 9 to 11 umol CO2/m2/s. CO2 saturation was estimated at approximately 1100 to 1200 ppm with maximum leaf Pn rates from 17 to 22 umol CO2/m2/s. Whole plant Pn rates increased with increased PAR. Maximum rates 4 to 5 umol CO2/m2/s (half that of individual leaves) occurred at approximately 1000 to 1100 umol/m2/s PAR. CO2 saturation was estimated at 1100 to 1200 ppm, with maximum whole plant Pn rates ranging from 7 to 8 umol CO2/m2/s. These data will be discussed in relation to respiration and mutual shading at the leaf canopy.

Studies on the productivity of tropical pasture plants. II. Growth analysis, photosynthesis, and respiration of 20 species of grasses and legumes in a controlled environment

1970 ◽  
Vol 21 (2) ◽  
pp. 183 ◽  
Author(s):  
MM Ludlow ◽  
GL Wilson
Keyword(s):  
Growth Analysis ◽  
Dark Respiration ◽  
Controlled Environment ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Similar Range ◽  
Net Assimilation ◽  
Photosynthesis And Respiration ◽  
Very High ◽  
Pasture Plants

A previous study of one grass and one legume at early vegetative stages has been extended to include a further nine species of each. It confirms the superior relative growth rates (RW) of grasses, arising from very high net assimilation rates (EA), in turn dependent on high photosynthetic rates (P). Leaf area ratios (FA) varied over a similar range in both groups. RW values of grasses in the second week after sowing varied from 0.41 to 0.55 gg-1 day-1; for legumes, they were 0.31-0.36. Corresponding EA values were 1.5-1.9 g dm-2 wk-1 in grasses, and 1.1-1.8 in legumes. Within both grasses and legumes, comparisons between species can be made with less certainty. In grasses, variation in FA combined with generally uniform EA values resulted in variable RW values. Both FA and EA varied in the legumes but were usually compensatory, leading to uniformity in RW. Watson and Hayashi's method of separating EA into photosynthetic and respiratory components was used. Differences both between and within grasses and legumes were shown, but there are probably important errors in this technique, particularly where there are discrepancies between light and dark respiration.

The Effects of Drought on Leaf Gas Exchange and Growth of Three Species of Herbaceous Perennials

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 540a-540
Author(s):  
K.J. Prevete ◽  
R.T. Fernandez
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Drought Tolerance ◽  
Transpiration Rate ◽  
Leaf Gas Exchange ◽  
Gas Analysis ◽  
Herbaceous Perennials ◽  
Effects Of Drought ◽  
Analysis System

Three species of herbaceous perennials were tested on their ability to withstand and recover from drought stress periods of 2, 4, and 6 days. Eupatorium rugosum and Boltonia asteroides `Snowbank' were chosen because of their reported drought intolerance, while Rudbeckia triloba was chosen based on its reported drought tolerance. Drought stress began on 19 Sept. 1997. Plants were transplanted into the field the day following the end of each stress period. The effects of drought on transpiration rate, stomatal conductance, and net photosynthetic rate were measured during the stress and throughout recovery using an infrared gas analysis system. Leaf gas exchange measurements were taken through recovery until there were no differences between the stressed plants and the control plants. Transpiration, stomatal conductance, and photosynthesis of Rudbeckia and Boltonia were not affected until 4 days after the start of stress. Transpiration of Eupatorium decreased after 3 days of stress. After rewatering, leaf gas exchange of Boltonia and Rudbeckia returned to non-stressed levels quicker than Eupatorium. Growth measurements were taken every other day during stress, and then weekly following transplanting. Measurements were taken until a killing frost that occurred on 3 Nov. There were no differences in the growth between the stressed and non-stressed plants in any of the species. Plants will be monitored throughout the winter, spring, and summer to determine the effects of drought on overwintering capability and regrowth.

StatPal II pH and Blood Gas Analysis System evaluated

1994 ◽  
Vol 40 (1) ◽  
pp. 124-129 ◽  
Author(s):  
R J Wong ◽  
J J Mahoney ◽  
J A Harvey ◽  
A L Van Kessel
Keyword(s):  
Point Of Care ◽  
Blood Gases ◽  
Blood Gas Analysis ◽  
Gas Analysis ◽  
Portable Instrument ◽  
Blood Gas ◽  
Target Value ◽  
Analysis System

Abstract We evaluated a new portable instrument, the PPG StatPal II pH and Blood Gas Analysis System, designed for "point-of-care" measurements of blood gases and pH. Inaccuracy (% of target value) and imprecision (CV%) were assessed by blood tonometry and comparison with a Corning 178. Within-day results for PCO2 inaccuracy and imprecision ranged from 98.2% to 102.9% and 3.3% to 3.9%, respectively; for PO2, these were 95.5% to 102.3% and 2.3% to 3.0%, respectively. Between-day results for PCO2 inaccuracy and imprecision ranged from 99.2% to 99.3% and from 2.9% to 3.2%, respectively; for PO2, the ranges were 96.2% to 98.2% and 2.6% to 3.0%, respectively. Two PCO2 outliers (in 645 samples = 0.3%) were observed. In general, tonometry recovery, measurement stability, and pH bias results for the StatPal II and Corning 178 were comparable. We conclude that the StatPal II performs within acceptable ranges of inaccuracy and imprecision.

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