scholarly journals Net Carbon Exchange Rate of Fragaria Species, Synthetic Octoploids, and Derived Germplasm

2012 ◽  
Vol 137 (3) ◽  
pp. 202-209 ◽  
Author(s):  
Rebecca M. Harbut ◽  
J. Alan Sullivan ◽  
John T.A. Proctor ◽  
Harry J. Swartz
Keyword(s):  
Exchange Rate ◽  
Light Response ◽  
Research Station ◽  
Carbon Exchange ◽  
Light Conditions ◽  
Response Curves ◽  
Low Light ◽  
Light Response Curves ◽  
Single Leaf ◽  
Net Carbon Exchange

The net carbon exchange rate (NCER) of Fragaria species, synthetic octoploids [SO (interspecific hybrids)], F1 (SO × cultivar), and first outcross [OC1 (F1 × cultivar)] hybrids were evaluated in both field and greenhouse conditions. Plants were grown in a field trial at the Elora Research Station in Ontario, Canada, for one season and then plants were dug and moved into a greenhouse where the trial was repeated during the next season. Single leaf photosynthesis measurements and light response curves were generated at different stages of plant development. Photosynthetic capacity of the species was related to the ecological background of the species with sun-adapted species having higher rates compared with the shade-adapted species. The Fragaria species and introgressed hybrids (F1 and OC1) had significantly higher NCERs compared with the cultivars with rates 28% and 23% higher, respectively. Species and hybrids also appear to have increased adaptability to both high and low light conditions. These increases in NCER may be a heterotic effect because NCER of the hybrids were consistently higher compared with the midparent values and in some cases, they were higher than the high parent. These results suggest that the introgression of lower-ploidy Fragaria species into the cultivated strawberry (Fragaria ×ananassa) may lead to increased NCER and light adaptability.

Comparative Net Photosynthesis of Four Hevea brasiliensis Clonal Seedlings

1978 ◽  
Vol 14 (4) ◽  
pp. 337-340 ◽  
Author(s):  
Zahar Samsuddin ◽  
Ivan Impens
Keyword(s):  
Hevea Brasiliensis ◽  
Light Response ◽  
Net Photosynthesis ◽  
Response Curves ◽  
Photosynthetic Rates ◽  
Light Response Curves ◽  
Single Leaf

SUMMARYSingle-leaf net photosynthesis versus light response curves of four Hevea brasiliensis clonal seedlings showed that it was possible to divide photosynthetic rates into high and low classes.

scholarly journals Evaluation of the importance of acclimation of needle structure, photosynthesis, and respiration to available photosynthetically active radiation in a Scots pine canopy

2001 ◽  
Vol 31 (7) ◽  
pp. 1235-1243 ◽  
Author(s):  
S Palmroth ◽  
P Hari
Keyword(s):  
Exchange Rate ◽  
Scots Pine ◽  
Photosynthetically Active Radiation ◽  
Light Response ◽  
Photosynthetic Parameters ◽  
Response Curves ◽  
Needle Age ◽  
Active Radiation ◽  
Light Response Curves ◽  
Light Gradient

We analyzed the combined effect of differences in the photosynthetic light response curve and in the distributions of photosynthetically active radiation (PAR) irradiance within the canopy on the CO2 exchange rates of Scots pine (Pinus sylvestris L.) shoots. Nitrogen concentration did not vary with depth within the canopy, but leaf mass per area (LMA) ranged from 58.2 to 95.2 g·m–2 (all needle age-classes pooled) and increased with increasing available PAR. The photosynthetic light response curves of 75 randomly sampled, 1-year-old shoots (with a fixed structure) were measured in the laboratory. No statistically significant differences in photosynthetic parameters or stomatal conductance either on an area or mass basis were detected between the top, middle, and bottom zones of the canopy. However, a significant decrease occurred in the area-based dark respiration rate (Rd) with increasing depth in the canopy. The area-based maximum CO2 exchange rate was weakly correlated with needle nitrogen content (Narea) and LMA, whereas Rd showed a higher correlation with both Narea and LMA. Estimates of the CO2 exchange rate over a day (24 h) in July suggest that the apparently small differences in mean light response curves of the canopy zones are reflected in the enhanced performance of shade needles in low light conditions because of reduced respiration costs. Based on our results, structural acclimation of needles along the light gradient, rather than changes in biochemical machinery, appears to be the more important acclimation process in Scots pine.

scholarly journals Interactive Effects of Light and CO2 on Photosynthesis and Growth of Brassica spp.

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 491D-491
Author(s):  
Jan M. Kossowski ◽  
David W. Wolfe
Keyword(s):  
Light Response ◽  
Light Level ◽  
Dry Mass ◽  
Compensation Point ◽  
Interactive Effects ◽  
Response Curves ◽  
Low Light ◽  
Light Response Curves ◽  
Nutrient Film Technique ◽  
Plant Dry Mass

Long- and short-term physiological responses of pak choi (Chinese cabbage, Brassica campestris cv. `Hypro') to elevated CO2 and light environments were evaluated in the series of growth chamber experiments. Plants were grown hydroponically (Nutrient Film Technique) at 25/18°C (day/night) temperature, a 16-h photoperiod, and at three CO2 levels (350, 700, 1400 ppm) and two light levels (200 and 400 μmol·m–2·s–1 PPFD). Relative to 350-ppm CO2 treatment, the final total plant dry mass in low light increased by 37% and 38% at 700 and 1400 ppm CO2, respectively. In high light the increase was 7% and 13% at 700 and 1400 ppm CO2, respectively. Light response curves showed a positive CO2 effect on light compensation point, a slight increase in quantum yield and increase in maximum Pn rates at elevated CO2. Carbon dioxide response curves (measured at saturating PPFD of 1600 μmol·m–2·s–1) showed no effect of growth light treatment on the CO2 compensation point, but a 20% to 30% higher maximum Pn rate at saturating CO2 in plants grown at the higher light level. Overall, the highest Pn rates and the highest plant dry mass at final harvest were found in plants grown at the 400 μmol·m–2·s–1 PPFD and 1400 ppm CO2. Relative beneficial CO2 effects, however, were the most pronounced in low light conditions.

Photosynthetic light-response curves

Planta ◽  
1993 ◽  
Vol 189 (2) ◽  
Author(s):  
E. �gren ◽  
J.R. Evans
Keyword(s):  
Light Response ◽  
Response Curves ◽  
Light Response Curves

scholarly journals Temperature response of photosynthesis and its interaction with light intensity in sweet orange leaf discs under non-photorespiratory condition

2006 ◽  
Vol 30 (4) ◽  
pp. 670-678 ◽  
Author(s):  
Rafael Vasconcelos Ribeiro ◽  
Eduardo Caruso Machado ◽  
Ricardo Ferraz de Oliveira
Keyword(s):  
Sweet Orange ◽  
Photochemical Efficiency ◽  
Temperature Response ◽  
Light Response ◽  
Photon Flux ◽  
O2 Evolution ◽  
Response Curves ◽  
Leaf Discs ◽  
Light Response Curves ◽  
Heat Effects

This study aimed to evaluate the response of photosynthesis (A), given by photosynthetic O2 evolution, to increasing temperature from 25 to 50ºC in sweet orange (Citrus sinensis (L.) Osbeck) leaf discs under non-photorespiring conditions. In order to evaluate the response of gross photosynthesis to temperature and the balance between photosynthetic and respiratory activities, respiration (Rd) rates were also measured, i.e. the O2 uptake in each temperature. In addition, light response curves of photosynthesis were performed by varying the photosynthetic photon flux density (PPFD) from 0 to 1160 µmol m-2 s-1 at 25 and 40ºC. The highest A values were observed at 35 and 40ºC, whereas the highest Rd values were noticed at 50ºC. A higher relationship A/Rd was found at 30 and 35ºC, suggesting an optimum temperature of 35ºC when considering the balance between photosynthesis and respiration under non-photorespiring condition. Overall, heat effects on plant metabolism were more evident when evaluating the relationship A/Rd. In light response curves, higher A values were also found at 40ºC under PPFD higher than 300 µmol m-2 s-1. Light saturation point of photosynthesis was increased at 40ºC, without significant change of quantum efficiency under low PPFD. Respiration was also enhanced at 40ºC, and as a consequence, the light compensation point increased. The better photosynthetic performance at 35-40ºC was supported by higher photochemical efficiency in both light and temperature response curves. The temperature-dependence of photosynthesis was affected by growth temperature, i.e. a high air temperature during plant growth is a probable factor leading to a higher photosynthetic tolerance to heat stress.

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