Physiological aspects of the ecology of Dicranum fuscescens in the subarctic. I. Acclimation and acclimation potential of CO2 exchange in relation to habitat, light, and temperature

1976 ◽  
Vol 54 (10) ◽  
pp. 1104-1119 ◽  
Author(s):  
Peter R. Hicklenton ◽  
Walter C. Oechel
Keyword(s):  
Dark Respiration ◽  
Environmental Parameters ◽  
Dry Weight ◽  
Co2 Exchange ◽  
Temperature Acclimation ◽  
Gas Analysis ◽  
Carbon Dioxide Exchange ◽  
Seasonal Temperature ◽  
Temperature Regimes ◽  
Lichen Woodland

Laboratory measurements of net carbon dioxide exchange in relation to light and temperature were made on Dicranum fuscescens Turn, at Schefferville, Quebec (latitude 55° N), during the summer of 1974. Net CO2 exchange was measured using an open-flow infrared gas analysis system. Moss samples were collected from two field sites (a lowland lichen woodland and highland semitundra region) immediately before the experiments. Temperature optima for photosynthesis in plants from both sites showed acclimation to higher temperatures in the middle of the season. Measured maximum rates of photosynthesis, attained in early July, equalled 2.1 mg CO2∙g dry weight−1∙h−1 in plants from the highland site and 0.74 mg CO2∙g dry weight−1∙h−1 in those from the lowland lichen woodland. Dark respiration rates showed no seasonal temperature acclimation. Radiation levels required for saturation of photosynthesis at optimum temperatures showed an increase from early season through midseason in samples from both populations. A reverse trend towards lower light requirements for saturation was detectable in the late season. Field-collected plants were exposed to different temperature regimes for [Formula: see text] months in growth chambers. During this period, temperature acclimation of photosynthesis to ambient temperature conditions elicited a rapid shift in optimum temperatures for photosynthesis over periods as short as 48 h. All results are discussed in relation to measured environmental parameters in the two study sites throughout the 1974 growing season.

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.

Productivity of Vegetable Crops in a Region of High Solar Input. III. Carbon Balance of Potato Crops

1974 ◽  
Vol 1 (2) ◽  
pp. 283 ◽  
Author(s):  
PJM Sale
Keyword(s):  
Carbon Balance ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Gas Analysis ◽  
Co2 Uptake ◽  
Co2 Efflux ◽  
Vegetable Crops ◽  
Weight Changes ◽  
Potato Crops

The carbon balance of potato crops has been studied by measuring canopy net photosynthesis and dark respiration losses with a field assimilation chamber and semi-closed gas analysis system. Results are given for the latter part of growth in both a spring-planted and a summer-planted crop. Net CO2 uptake increased with solar input to reach 35–40mg dm-2 (ground area) h-1 at 400–450 W m-2, but light saturation then occurred and little or no further uptake resulted from increases in solar input up to 1000 W m-2. This supports the previous conclusion that net photosynthesis in the potato is determined by the size of the 'sink' provided by the developing tubers. The imposed experimental variables of reduced solar input (21 and 34% shade) and soil moisture were found not to affect the relation between solar input and CO2 uptake, and the effect of chamber temperature was also very small. Dark respiration rates of the canopy were markedly sensitive to temperature, and also to the solar input prior to measurement. Respiration from the below-ground plant parts accounted for a considerable part of the total plant respiration. In all, 15–20 % of the net assimilation during daylight hours was lost by night respiration. There was little variation in CO2 efflux from uncropped soil during the experiments. Dry weight changes calculated from the gasometric measurements were in accordance with those found from previous growth analysis. * Part II, Aust. J. Agric. Res., 1973, 24, 751–62.

scholarly journals Carbon and Nitrogen Economy of Developing Rabbiteye Blueberry Fruit

1992 ◽  
Vol 117 (1) ◽  
pp. 139-145 ◽  
Author(s):  
Keith T. Birkhold ◽  
Karen E. Koch ◽  
Rebecca L. Darnell
Keyword(s):  
Fruit Ripening ◽  
Fruit Development ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Carbon Dioxide Exchange ◽  
N Content ◽  
Vaccinium Ashei ◽  
Fruit Photosynthesis ◽  
C And N

Carbon dioxide exchange, dry weight, C, and N content of `Bonita' and `Climax' blueberry (Vaccinium ashei Reade) fruit were measured from anthesis through fruit ripening to quantify developmental changes in amounts of imported C and N required for fruit development. Net photosynthesis occurred in fruit of both rabbiteye cultivars from petal fall through color break. During this time, fruit net photosynthesis declined from 16 μmol CO2/g fresh weight (FW) per hour for `Bonita' and 22 μmol CO2/g FW per hour for `Climax' to 0.2 μmol CO2/g FW per hour for both. Dark respiration for both cultivars declined following petal fall from 16 μmol CO2/g FW per hour to 3 μmol CO2/g FW per hour before increasing at fruit ripening to 9 μmol CO2/g FW per hour. Fruit C content was constant at 0.43 mg C/mg dry weight (DW) throughout development, while N content declined from 0.05 mg N/mg DW at petal fall to 0.01 mg N/mg DW at ripeness. DW accumulation and respiration accounted for 63% and 37%, respectively, of the total C requirement for fruit development. Fruit photosynthesis was estimated to contribute 15% of the total C required for fruit development in both cultivars; however, fruit photosynthesis supplied 50% of the C required during the first 10 days after bloom and 85% during the 5 days after petal fall. This large, early contribution of C from fruit photosynthesis may aid in the establishment of fruit until the current season's vegetative growth can supplement plant carbohydrate reserves in providing C for fruit development.

scholarly journals Net Carbon Dioxide Exchange Rates and Predicted Growth Patterns in Alstroemeria `Jacqueline' at Varying Irradiances, Carbon Dioxide Concentrations, and Air Temperatures

1994 ◽  
Vol 119 (6) ◽  
pp. 1265-1275 ◽  
Author(s):  
E.D. Leonardos ◽  
M.J. Tsujita ◽  
B. Grodzinski
Keyword(s):  
Carbon Dioxide ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Growth Patterns ◽  
High Yield ◽  
Carbon Dioxide Exchange ◽  
Air Temperatures ◽  
Temperature Regimes ◽  
Whole Plant ◽  
Whole Plants

The influence of irradiance, CO2 concentration, and air temperature on leaf and whole-plant net C exchange rate (NCER) of Alstroemeria `Jacqueline' was studied. At ambient CO2, leaf net photosynthesis was maximum at irradiances above 600 μmol·m-2·s-1 photosynthetically active radiation (PAR), while whole-plant NCER required 1200 μmol·m-2·s-1 PAR to be saturated. Leaf and whole-plant NCERs were doubled under CO2 enrichment of 1500 to 2000 μl CO2/liter. Leaf and whole-plant NCERs declined as temperature increased from 20 to 35C. Whereas the optimum temperature range for leaf net photosynthesis was 17 to 23C, whole-plant NCER, even at high light and high CO2, declined above 12C. Dark respiration of leaves and whole plants increased with a Q10 of ≈2 at 15 to 35C. In an analysis of day effects, irradiance, CO2 concentration, and temperature contributed 58%, 23%, and 14%, respectively, to the total variation in NCER explained by a second-order polynomial model (R2 = 0.85). Interactions among the factors accounted for 4% of the variation in day C assimilation. The potential whole-plant growth rates during varying greenhouse day and night temperature regimes were predicted for short- and long-day scenarios. The data are discussed with the view of designing experiments to test the importance of C gain in supporting flowering and high yield during routine harvest of Alstroemeria plants under commercial greenhouse conditions.

Comparative CO2 exchange patterns in mosses from two tundra habitats at Barrow, Alaska

1976 ◽  
Vol 54 (12) ◽  
pp. 1355-1369 ◽  
Author(s):  
Walter C. Oechel ◽  
Nigel J. Collins
Keyword(s):  
Light Intensity ◽  
Water Content ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Co2 Exchange ◽  
Polar Regions ◽  
Light Intensities ◽  
Matter Production ◽  
Exchange Patterns

The effects of variation in light intensity, temperature, and water content on rates of net photosynthesis and dark respiration have been investigated in two common tundra mosses, Polytrichum alpinum from drier habitats and Calliergon sarmentosum from wetter habitats at Barrow, Alaska. Optimum temperatures for net photosynthesis of 10–15 °C for both species and saturating light intensities (photosynthetically active radiation (PhAR), 400–700 nm) of about 0.12 cal cm−2 min−1 for P. alpinum and 0.15 cal cm−2 min−1 for C. sarmentosum correlate well with measurements of light intensity and moss tissue temperatures made over the season at the collection site. It is suggested that depressions in net photosynthetic rates around midday might be caused by supraoptimal temperatures and possibly supraoptimal light intensities. Calliergon sarmentosum, a semiaquatic species required a higher water content (about 450% dry weight) than P. alpinum (about 200%) to reach maximal rates of net photosynthesis. Mean maximal rates of net photosynthesis ranged from about 2.6 to 4.4 mg CO2 g−1 dry weight h−1 for P. alpinum and from about 1.5 to 3.0 mg CO2 g−1 dry weight h−1 for C. sarmentosum. Predictions of net annual production have been made for both species. Predicted levels of 171 g C m−2 per 50-day season for C. sarmentosum compare well with results obtained for species of similar growth form elsewhere in polar regions. For P. alpinum the predicted level of 38.5 g C m−2 per 50-day season compares with observed dry matter production at the same site of 43 g m−2 per season.

Characteristics of the canopy, root system and grain yield of a crop of Lupinus angustifolius cv. Unicrop

1975 ◽  
Vol 26 (3) ◽  
pp. 497 ◽  
Author(s):  
EAN Greenwood ◽  
P Farrington ◽  
JD Beresford
Keyword(s):  
Carbon Dioxide ◽  
Grain Yield ◽  
Leaf Area ◽  
Time Course ◽  
Dry Weight ◽  
Grain Filling ◽  
Main Axis ◽  
Carbon Dioxide Exchange ◽  
Area Index ◽  
Plant Parts

The time course of development of a lupin crop was studied at Bakers Hill, Western Australia. The aim was to gain insight into the crop factors influencing yield. Weekly measurements were made of numbers and weights of plant parts, and profiles of roots, leaf area and light interception. A profile of carbon dioxide in the crop atmosphere was taken at the time of maximum leaf area, and the net carbon dioxide exchange (NCE) of pods was estimated for three successive weeks. The crop took 10 weeks to attain a leaf area index (LAI) of 1 and a further 9 weeks to reach a maximum LAI of 3.75, at which time only 33% of daylight reached the pods on the main axis. Once the maximum LAI was attained at week 19, leaf fall accelerated and rapid grain filling commenced almost simultaneously on all of the three orders of axes which had formed pods. Measurements of NCE between pods on the main axis and the air suggest that the assimilation of external carbon dioxide by the pods contributed little to grain filling. Grain dry weight was 2100 kg ha-1 of which 30%, 60% and 10% came from the main axis, first and second order apical axes respectively. Only 23% of the flowers set pods and this constitutes an important physiological limitation to grain yield.

Infection of adventitious roots of Agrostis palustris by Pythium species at different temperature regimes

1994 ◽  
Vol 72 (3) ◽  
pp. 378-383 ◽  
Author(s):  
Clinton F. Hodges ◽  
Douglas A. Campbell
Keyword(s):  
Low Temperatures ◽  
Adventitious Roots ◽  
Root Hairs ◽  
Dry Weight ◽  
Agrostis Palustris ◽  
Pythium Species ◽  
Root Tips ◽  
Pythium Arrhenomanes ◽  
Temperature Regimes ◽  
Disease Complexes

Pathogenicity of several isolates of Pythium species to the adventitious roots of Agrostis palustris was evaluated at high (35:24, light:dark) and low (24:13 °C, light:dark) temperature regimes. Isolates of P. graminicola–arrhenomanes, P. rostratum, P. torulosum, P. vanterpoolii, and one unclassified species were evaluated. All isolates of all species infected roots. Some isolates of P. graminicola–arrhenomanes (PGA-5), P. torulosum (PT-1, PT-2, PT-3, PT-5), P. vanterpoolii (PV-1), and an unclassified species (UP-1) infected roots and decreased dry weight at both the high and low temperature regimes. Other isolates of P. graminicola–arrhenomanes (PGA-1, PGA-2, PGA-4, PGA-6, PGA-7) and P. torulosum (PT-4) infected roots and decreased dry weight only at the high temperatures. Isolate PGA-7 of P. graminicola–arrhenomanes also stimulated plant growth at low temperatures. The remaining isolates of P. graminicola–arrhenomanes (PGA-3), P. rostratum (PR-1), and P. vanterpoolii (PV-2) infected roots and decreased dry weight only at the low temperatures. Infection of roots was limited to root hairs, root tips, and epidermal and cortical tissues. The observations are discussed relative to the function of Pythium species as minor root pathogens and their potential function in disease complexes. Key words: disease complexes, infection, minor pathogens, pathogenesis, pathogenicity, Pythium arrhenomanes, P. graminicola, P. graminicola–arrhenomanes, P. rostratum, P. torulosum, P. vanterpoolii.

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.

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