scholarly journals Canopy Photosynthesis and Time-of-day Application of Supplemental Light

HortScience ◽  
2009 ◽  
Vol 44 (5) ◽  
pp. 1284-1290 ◽  
Author(s):  
Jakob Markvart ◽  
Eva Rosenqvist ◽  
Helle Sørensen ◽  
Carl-Otto Ottosen ◽  
Jesper M. Aaslyng
Keyword(s):  
Dark Respiration ◽  
High Growth ◽  
Net Photosynthesis ◽  
Time Of Day ◽  
Photon Flux ◽  
Carbon Gain ◽  
Climate Control ◽  
Low Light ◽  
Light Intensities ◽  
Supplemental Lighting

There is increasing use of electricity for supplemental lighting in the northern European greenhouse industry. One reason for this may be to secure a high growth rate during low-light periods by an attempt to increase net photosynthesis. We wanted to clarify which period of the day resulted in the best use of a 5-h supplemental light period for photosynthesis and growth. The periods tested were supplemental light during the night, day, morning, and evening. The experiments were carried out in daylight climate chambers measuring canopy gas exchange. The air temperature was 25 °C and the CO2 level ≈900 ppm. Vegetative chrysanthemum was used, because this species responds quickly to change in light level. The leaf areas of the plant canopies were nondestructively measured each week during the 4-week experimental period. The fact that the quantum yield of photosynthesis is greater at low than at high light intensities favors the use of supplemental light during the dark period, but growth measured as dry weight of the treated plants at the end of the experiments was not significantly different given identical light integrals of the treatments. However, one experiment indicated that increased time with dark hours during day and night (24 h) might decrease net photosynthesis. The assimilation per unit leaf area was approximately the same during times of sunlight through a diffusing screen at 100 μmol·m−2·s−1 of photosynthetic photon flux (PPF) as during times of supplemental (direct) light application at PPF of 200 μmol·m−2·s−1 by high-pressure sodium lamps. We conclude that during the winter and periods of low light intensities, the daily carbon gain does not depend on the time of supplemental light application, but is linked to the total light integral. However, extended time with dark hours during day and night (24 h) might be a disadvantage because of longer periods with dark respiration and subsequent loss of carbon. Our results indicate that during times of low light conditions, it is not necessary to include factors such as the timing of supplemental lighting application to achieve higher net photosynthesis in climate control strategies.

Interactions entre mitochondries et chloroplastes dans la cellule. II. Action du DBMIB, de l'antimycine A et du FCCP sur la spore de Funaria hygrometrica

1977 ◽  
Vol 55 (12) ◽  
pp. 1650-1659 ◽  
Author(s):  
D. Chevallier ◽  
R. Douce ◽  
F. Nurit
Keyword(s):  
Cytochrome Oxidase ◽  
Dark Respiration ◽  
High Light ◽  
Light Conditions ◽  
Oxygen Production ◽  
Low Light ◽  
Funaria Hygrometrica ◽  
Light Intensities

The effect of DBMIB, antimycine A, and FCCP on respiration and photosynthesis of intact chlorophyllic moss (Funaria hygrometrica) spore was investigated.Antimycine A (1 μM) strongly inhibited dark respiration, was without effect on photosynthesis at high light intensities (above the saturation plateau values), and stimulated photosynthesis at low light intensities (below the saturation plateau values).DBMIB (3 μM) inhibited photosynthesis and was without effect, even under light conditions, on the dark respiration. Low amount of FCCP (3 μM) partially inhibited oxygen production at high light intensities. In this case, the inhibition observed was partially relieved by 1 μM antimycine A or 30 μM of KCN; higher concentration of FCCP totally inhibited the oxygen production.It seems likely, therefore, that in the chlorophyllic moss spore the cytochrome oxidase pathway is not functioning under high light intensities and that this inhibition of respiration is attributable to the low cytoplasmic ADP:ATP ratio.

scholarly journals Photosynthetic responses of three common mosses from continental Antarctica

2005 ◽  
Vol 17 (3) ◽  
pp. 341-352 ◽  
Author(s):  
STEFAN PANNEWITZ ◽  
T.G. ALLAN GREEN ◽  
KADMIEL MAYSEK ◽  
MARK SCHLENSOG ◽  
ROD SEPPELT ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Content ◽  
Dark Respiration ◽  
Temperature Response ◽  
Environmental Parameters ◽  
Net Photosynthesis ◽  
Photon Flux ◽  
Terrestrial Vegetation ◽  
Moss Species ◽  
Victoria Land

Predicting the effects of climate change on Antarctic terrestrial vegetation requires a better knowledge of the ecophysiology of common moss species. In this paper we provide a comprehensive matrix for photosynthesis and major environmental parameters for three dominant Antarctic moss species (Bryum subrotundifolium, B. pseudotriquetrum and Ceratodon purpureus). Using locations in southern Victoria Land, (Granite Harbour, 77°S) and northern Victoria Land (Cape Hallett, 72°S) we determined the responses of net photosynthesis and dark respiration to thallus water content, thallus temperature, photosynthetic photon flux densities and CO2 concentration over several summer seasons. The studies also included microclimate recordings at all sites where the research was carried out in field laboratories. Plant temperature was influenced predominantly by the water regime at the site with dry mosses being warmer. Optimal temperatures for net photosynthesis were 13.7°C, 12.0°C and 6.6°C for B. subrotundifolium, B. pseudotriquetrum and C. purpureus, respectively and fall within the known range for Antarctic mosses. Maximal net photosynthesis at 10°C ranked as B. subrotundifolium > B. pseudotriquetrum > C. purpureus. Net photosynthesis was strongly depressed at subzero temperatures but was substantial at 0°C. Net photosynthesis of the mosses was not saturated by light at optimal water content and thallus temperature. Response of net photosynthesis to increase in water content was as expected for mosses although B. subrotundifolium showed a large depression (60%) at the highest hydrations. Net photosynthesis of both B. subrotundifolium and B. pseudotriquetrum showed a large response to increase in CO2 concentration and this rose with increase in temperature; saturation was not reached for B. pseudotriquetrum at 20°C. There was a high level of variability for species at the same sites in different years and between different locations. This was substantial enough to make prediction of the effects of climate change very difficult at the moment.

scholarly journals Photochemical Acclimation of Three Contrasting Species to Different Light Levels: Implications for Optimizing Supplemental Lighting

2017 ◽  
Vol 142 (5) ◽  
pp. 346-354 ◽  
Author(s):  
Shuyang Zhen ◽  
Marc W. van Iersel
Keyword(s):  
Electron Transport ◽  
Light Intensity ◽  
Photochemical Efficiency ◽  
Light Response ◽  
High Light ◽  
Photon Flux ◽  
Ambient Light ◽  
Response Curves ◽  
Low Light ◽  
Supplemental Lighting

Photosynthetic responses to light are dependent on light intensity, vary among species, and can be affected by acclimation to different light environments (e.g., light intensity, spectrum, and photoperiod). Understanding how these factors affect photochemistry is important for improving supplemental lighting efficiency in controlled-environment agriculture. We used chlorophyll fluorescence to determine photochemical light response curves of three horticultural crops with contrasting light requirements [sweetpotato (Ipomea batatas), lettuce (Lactuca sativa), and pothos (Epipremnum aureum)]. We also quantified how these responses were affected by acclimation to three shading treatments-full sun, 44% shade, and 75% shade. The quantum yield of photosystem II (ΦPSII), a measure of photochemical efficiency, decreased exponentially with increasing photosynthetic photon flux (PPF) in all three species. By contrast, linear electron transport rate (ETR) increased asymptotically with increasing PPF. Within each shading level, the high-light-adapted species sweetpotato used high light more efficiently for electron transport than light-intermediate lettuce and shade-tolerant pothos. Within a species, plants acclimated to high light (full sun) tended to have higher ΦPSII and ETR than those acclimated to low light (44% or 75% shade). Nonphotochemical quenching (NPQ) (an indicator of the amount of absorbed light energy that is dissipated as heat) was upregulated with increasing PPF; faster upregulation was observed in pothos as well as in plants grown under 75% shade. Our results have implications for supplemental lighting: supplemental light is used more efficiently and results in a greater increase in ETR when provided at low ambient PPF. In addition, high-light-adapted crops and crops grown under relatively high ambient light can use supplemental light more efficiently than low-light-adapted crops or those grown under low ambient light.

scholarly journals Microclimatic and ecophysiological conditions experienced by epiphytic bryophytes in an Amazonian rain forest

2019 ◽  
Author(s):  
Nina Löbs ◽  
David Walter ◽  
Cybelli G. G. Barbosa ◽  
Sebastian Brill ◽  
Gabriela R. Cerqueira ◽  
...  
Keyword(s):  
Rain Forest ◽  
Forest Floor ◽  
Dark Respiration ◽  
Physiological Activity ◽  
Dry Season ◽  
Photon Flux ◽  
Monthly Average ◽  
Light Intensities ◽  
Amazonian Rain Forest ◽  
Water Contents

Abstract. In the Amazonian rain forest, major parts of trees and shrubs are covered by epiphytic cryptogams of great taxonomic variety, but their relevance in biosphere-atmosphere exchange, climate processes, and nutrient cycling are largely unknown. As cryptogams are poikilohydric organisms, they are physiologically active only under moist conditions. Thus, information on their water content, as well as temperature and light conditions experienced by them are essential to analyzing their impact on local, regional, and even global biogeochemical processes. In this study, we present data on the microclimatic and ecophysiological conditions of epiphytic bryo-phytes along a vertical gradient and combine these with mesoclimate data collected at the Amazon Tall Tower Observatory (ATTO) in the Amazonian rain forest between October 2014 and December 2016. While the monthly average mesoclimatic ambient light intensities above the canopy revealed only minor variations, the light intensities incident on the bryophytes showed different patterns at different heights, probably depending on individual shading by vegetation. At 1.5 m height, monthly average light intensities were similar throughout the year and individual values were extremely low, exceeding 5 µmol m−2 s−1 pho-tosynthetic photon flux density only during 8 % of the time. Temperatures showed only minor variations throughout the year with higher values and larger height-dependent differences during the dry season. Water contents of bryophytes varied depending on precipitation and air humidity. Whereas bryophytes at higher levels were affected by frequent wetting and drying events, those close to the forest floor remained wet over longer time spans during the wet seasons. Based on estimates of the potential duration of net pho-tosynthesis and dark respiration, our data suggest that water contents are decisive for overall physiological activity, and light intensities determine whether net photosynthesis or dark respiration occurs, whereas temperature variations are only of minor relevance in this environment. In general, bryophytes growing close to the forest floor are limited by light availability, while those growing in the canopy must withstand larger variations in microclimatic conditions, especially in the dry season. Measurements of CO2 gas ex-change are essential to elucidate their physiological activity patterns in greater detail.

Genotypic Variation in Light and Temperature Response of Photosynthesis in Nothofagus solandri Var. cliffortioides and N. menziesii

1996 ◽  
Vol 23 (4) ◽  
pp. 421 ◽  
Author(s):  
OJ Sun ◽  
GB Sweet
Keyword(s):  
New Zealand ◽  
Dark Respiration ◽  
Genotypic Variation ◽  
Temperature Response ◽  
Light Response ◽  
Net Photosynthesis ◽  
Photosynthetic Photon Flux Density ◽  
Ecosystem Dynamics ◽  
Photon Flux ◽  
Photon Flux Density

Responses of photosynthesis to light and temperature were studied in two Nothofagus species native to New Zealand: N. solandri var. cliffortioides (Hook. f.) Poole and N. menziesii (Hook. f.) Oerst.. Measurements of leaf photosynthesis were made in a controlled environment growth chamber at photosynthetic photon flux density between 0 and 700 μmol m-2 s-1 with temperatures set for 10, 20 and 25�C, on seedlings previously grown in a glasshouse from seed of three different origins. In both species, pronounced intraspecific variation was shown in dark respiration, light compensation point and light-saturated net photosynthesis (Amax). Seedlings of N. solandri showed higher dark respiration and light compensation levels than N. menziesii seedlings, but the two species did not differ in Amax. Change in temperature resulted in significant change in the response of photosynthesis to light in both N. solandri and N. menziesii. The differences between N. solandri and N. menziesii in light response of photosynthesis are discussed in terms of ecosystem dynamics of Nothofagus forests in New Zealand.

CARBON GAIN IN COFFEA ARABICA DURING CLEAR AND CLOUDY DAYS IN THE WET SEASON

2006 ◽  
Vol 42 (2) ◽  
pp. 147-164 ◽  
Author(s):  
J. C. RONQUIM ◽  
C. H. B. A. PRADO ◽  
P. NOVAES ◽  
J. I. FAHL ◽  
C. C. RONQUIM
Keyword(s):  
Gas Exchange ◽  
Coffea Arabica ◽  
Leaf Gas Exchange ◽  
Photochemical Efficiency ◽  
Vapour Pressure Deficit ◽  
Net Photosynthesis ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Carbon Gain ◽  
Wet Season

Three cultivars of Coffea arabica, Catuaí Vermelho IAC 81, Icatu Amarelo IAC 2944 and Obatã IAC 1669–20, were evaluated in relation to leaf gas exchange and potential photochemical efficiency of photosystem II under field conditions on clear and cloudy days in the wet season in southeast Brazil. Independent of levels of irradiance, leaf water potential (υleaf) values were always higher than the minimum required to affect daily net photosynthesis (PN). PN, stomatal conductance (gs), leaf transpiration (E) and the index of photochemical efficiency (Fv/Fm) declined on a clear day in all cultivars. The depression of leaf gas exchange and Fv/Fm (specially around midday) caused a strong decrease (about 70 %) in daily carbon gain on a clear day. Under cloudless conditions, gs and PN were correlated with the air vapour pressure deficit (VPDair), but not with photosynthetic photon flux density (PPFD) values. On a cloudy day, the daily carbon gain was barely limited by PPFD below 800 μmol m−2 s−1, the Fv/Fm values showed a slight decrease around midday, and gs and PN were positively correlated with PPFD but not with VPDair. By contrast, irrespective of the contrasting irradiance conditions during the day, PN and E were correlated with gs.

Maximum growth potential in loblolly pine: results from a 47-year-old spacing study in Hawaii

2010 ◽  
Vol 40 (10) ◽  
pp. 1914-1929 ◽  
Author(s):  
Lisa J. Samuelson ◽  
Thomas L. Eberhardt ◽  
John R. Butnor ◽  
Tom A. Stokes ◽  
Kurt H. Johnsen
Keyword(s):  
Loblolly Pine ◽  
Dark Respiration ◽  
Basal Area ◽  
Net Photosynthesis ◽  
Maximum Growth ◽  
Growth Potential ◽  
Carbon Gain ◽  
Native Range ◽  
Woody Root ◽  
Area And Volume

Growth, allocation to woody root biomass, wood properties, leaf physiology, and shoot morphology were examined in a 47-year-old loblolly pine ( Pinus taeda L.) density trial located in Maui, Hawaii, to determine if stands continued to carry the high density, basal area, and volume reported at younger ages and to identify potential factors controlling expression of maximum growth potential. Basal area and volume were similar among spacings (square: 1.8, 2.4, 3.0, and 3.7 m) and averaged 93 m2·ha–1 and 1076 m3·ha–1, respectively, and were double the maxima reported for loblolly pine in its native range. Spacing had a significant influence on density, quadratic mean diameter, and height. Ring-specific gravity and percent latewood were similar among spacing treatments but values were high compared to mainland stands. Leaf light-saturated net photosynthesis, dark respiration, stomatal conductance, and quantum yield were comparable with values reported for loblolly pine in its native range. Foliar calcium concentrations, specific leaf area, and flush number were high in the Hawaii study. Higher carrying capacity in Hawaii may be related to a more favorable climate conducive to year-round leaf carbon gain, high nutrient availability, increased flushing, and less allocation to belowground mass.

Photosynthetic light and temperature responses of Eucalyptus cloeziana and Eucalyptus argophloia

2003 ◽  
Vol 51 (5) ◽  
pp. 573 ◽  
Author(s):  
Michael R. Ngugi ◽  
Mark A. Hunt ◽  
David Doley ◽  
Paul Ryan ◽  
Peter J. Dart
Keyword(s):  
Quantum Yield ◽  
Dark Respiration ◽  
Temperature Response ◽  
Net Photosynthesis ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Response Curves ◽  
Growth Environment ◽  
Eucalyptus Cloeziana

Acclimation of gas exchange to temperature and light was determined in 18-month-old plants of humid coastal (Gympie) and dry inland (Hungry Hills) provenances of Eucalyptus cloeziana F.Muell., and in those of a dry inland provenance of Eucalyptus argophloia Blakely. Plants were acclimated at day/night temperatures of 18/13, 23/18, 28/23 and 33/28�C in controlled-temperature glasshouses for 4 months. Light and temperature response curves were measured at the beginning and end of the acclimation period. There were no significant differences in the shape and quantum-yield parameters among provenances at 23, 28 and 33�C day temperatures. Quantum yield [μmol CO2 μmol–1 photosynthetic photon flux density (PPFD)] ranged from 0.04 to 0.06 and the light response shape parameter ranged from 0.53 to 0.78. Similarly, no consistent trends in the rate of dark respiration for plants of each provenance were identified at the four growth temperatures. Average values of dark respiration for the plants of the three provenances ranged from 0.61 to 1.86 μmol m–2 s–1. The optimum temperatures for net photosynthesis increased from 23 to 32�C for the humid- and from 25 to 33�C for the dry-provenance E. cloeziana and from 21 to 33�C for E. argophloia as daytime temperature of the growth environment increased from 18 to 33�C. These results have implications in predicting survival and productivity of E. cloeziana and E. argophloia in areas outside their natural distribution.

Growth kinetics of Marquis wheat. IV. Temperature dependence

1973 ◽  
Vol 51 (4) ◽  
pp. 729-736 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Light Intensity ◽  
Plant Growth ◽  
Net Photosynthesis ◽  
Absolute Maximum ◽  
Temperature Optimum ◽  
Differential Growth ◽  
Low Light ◽  
Growth Coefficient ◽  
Light Intensities ◽  
Kinetics Of

Earlier described data from this laboratory were subjected to primary growth analysis. The plants had been grown in constant conditions of light intensity (200 to 2500 ft-c) and temperature (10° to 30 °C) at five different settings each. Multiple temperature optima were revealed and interpreted. The computed maximum plant growth coefficient was highest in value at 25 °C (plant kmL = 0.44 day−1) and secondarily so at 15 °C, but at the experimental light intensities the plant growth coefficient was maximal at 15 °C. The higher temperature optimum was characteristic of roots and "stems" (stem plus leaf sheaths) whose growth coefficients displayed a prominent peak at 25 °C (root kmL ~ 0.8 day−1, "stem" kmL = 0.4 day−1). This optimum was shifted downward with decreasing light intensity until temperature insensitivity was attained at low light intensity. The low-temperature optimum at 15 °C was principally displayed by leaf blades (lamina kmL = 0.47 day−1) whose computed maximum growth coefficient also showed a secondary maximum at 25°, but the 15 °C peak was the only one evident at low light intensities. It was tentatively concluded that the 25 °C temperature optimum was that of net translocation, and that the 15 °C temperature optimum was that of net photosynthesis in which photosynthesis was primarily balanced by photorespiration in wheat. The differential growth of the organs represented their relative sink strengths for attracting growth substrate, as dependent on light intensity and temperature. The availability of photosynthate was considered to be the dominating factor in the kinetics of growth free from inorganic limitations. When there was very little photosynthate the tissues benefited from translocation on a "first come first serve" basis. The high values of kmL pushed the absolute maximum plant growth coefficient, kM, of Marquis wheat toward 0.5 or 50% per day, and the basis of the advantage over previous approximations must be elucidated by further experiments. The computed relative efficiency of the use of photosynthate for growth was temperature dependent, but its value at optimum temperature was similar to previous estimates.

Regenerative Succession of Tristaniopsis laurina and Acmena smithii in Riparian Warm Temperate Rain-Forest in Victoria, in Relation to Light and Nutrient Regimes

1990 ◽  
Vol 38 (2) ◽  
pp. 111 ◽  
Author(s):  
DR Melick
Keyword(s):  
Dark Respiration ◽  
Ecological Status ◽  
Photon Flux ◽  
Light Conditions ◽  
Growth Responses ◽  
Low Light ◽  
Light Regimes ◽  
Temperate Rain Forest ◽  
Warm Temperate ◽  
Regenerative Succession

Tristaniopsis laurina and Acmena smithii often form a dominant association in riparian warm temperate rainforest communities in Victoria. The photosynthetic and morphological responses of seedlings of these species to varied light regimes, and the growth responses of seedlings in different nutrient regimes were examined in the laboratory. Acmena smithii was the most shade tolerant, having the lowest light compensation points, dark respiration rates and greater increases in leaf area ratio under low light conditions. Tristaniopsis laurina consistently demonstrated greater maximum rates of leaf photosynthesis at higher photon flux densities. In response to increased nutrients, T. laurina seedlings showed a marked increase in growth and a decrease in root/shoot ratios, while A. smithii demonstrated relatively small growth increases and showed an increase in root/shoot ratios. These results are discussed in relation to the ecological status of these species within the rainforest communities.

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