Photon flux density and temperature-dependent responses of photosynthesis and photosystem II performance of apple leaves grown in field conditions

2015 ◽  
Vol 42 (8) ◽  
pp. 782 ◽  
Author(s):  
Dennis H. Greer
Keyword(s):  
Electron Transport ◽  
Flux Density ◽  
Leaf Temperature ◽  
Field Conditions ◽  
Photon Flux ◽  
Photochemical Quenching ◽  
Photon Flux Density ◽  
Temperature Dependent ◽  
Light Responses ◽  
Non Photochemical Quenching

The process of photosynthesis depends on the light, and is modulated by leaf temperature and their interaction is important to understand how climate affects photosynthesis. Photosynthetic and PSII light responses at a range of leaf temperatures were measured on leaves of apple (Malus domestica Borkh. cv. Red Gala) trees growing in field conditions. The objective was to assess the interaction between photon flux density (PFD) and temperature on these processes. Results showed leaf temperature strongly modulated the PFD-dependent response of photosynthesis and PSII performance. An interaction on photosynthesis occurred, with temperature affecting saturated rates as well as PFDs saturating photosynthesis. The efficiency of PSII electron transport (operating and maximum in light) universally declined with increasing PFD but temperature strongly influenced the response. Rates of PSII electron transport at saturating PFDs were affected by temperatures. Both photochemical quenching and non-photochemical quenching also responded strongly to temperature but at high PFDs, photochemical quenching increased linearly with decreasing temperatures while non-photochemical quenching increased curvilinearly with increasing temperatures. Modelling revealed changes in photosynthesis were positively correlated with rates of electron transport. These results greatly enhance our understanding of photosynthesis and the underpinning processes and their responses to temperature and PFD.

Short-term temperature dependency of the photosynthetic and PSII photochemical responses to photon flux density of leaves of Vitis vinifera cv. Shiraz vines grown in field conditions with and without fruit

2019 ◽  
Vol 46 (7) ◽  
pp. 634 ◽  
Author(s):  
Dennis H. Greer
Keyword(s):  
Maximum Efficiency ◽  
Photon Flux ◽  
Photochemical Quenching ◽  
Photon Flux Density ◽  
Temperature Dependent ◽  
Psii Photochemistry ◽  
Acclimation Response ◽  
Summer Temperatures ◽  
Non Photochemical Quenching ◽  
The Impact

Shiraz vines grown outdoors with and without a crop load were used to determine photosynthetic and chlorophyll fluorescence responses to light across a range of leaf temperatures to evaluate the impact of presence/absence of a sink on these responses. Results indicate maximum rates of photosynthesis and light saturation in fruiting vines were biased towards higher temperatures whereas these processes in vegetative vines were biased towards lower temperatures. The maximum efficiency of PSII photochemistry was similarly biased, with higher efficiency for the vegetative vines below 30°C and a higher efficiency for the fruiting vines above. The quantum efficiency of PSII electron transport was generally higher across all temperatures in the fruiting compared with vegetative vines. Photochemical quenching was not sensitive to temperature in fruiting vines but strongly so in vegetative vines, with an optimum at 30°C and marked increases in photochemical quenching at other temperatures. Non-photochemical quenching was not strongly temperature dependent, but there were marked increases in both treatments at 45°C, consistent with marked decreases in assimilation. These results suggest demand for assimilates in fruiting vines induced an acclimation response to high summer temperatures to enhance assimilate supply and this was underpinned by comparable shifts in PSII photochemistry.

Photosynthetic responses of muskmelon (Cucumis melo L.) to photon flux density, leaf temperature and CO2 concentration

2003 ◽  
Vol 83 (2) ◽  
pp. 393-399 ◽  
Author(s):  
N. Chen ◽  
Y. Gan ◽  
G. Wang
Keyword(s):  
Flux Density ◽  
Open Field ◽  
Cucumis Melo ◽  
Northwest China ◽  
Leaf Temperature ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light Saturation ◽  
Rate Of Increase ◽  
Cucumis Melo L

Two cultivars (Huanghemi and Elizabeth) of muskmelon (Cucumis melo L.) were evaluated to determine the effect of photon flux density (PFD), leaf temperature, and CO,2 concentration on the net photosynthetic rate (Pn). The cultivars were evaluated under open field and solar-heated greenhouse conditions in northwest China. The Pn increased as the PFD increased, and then the rate of increase in Pn declined for Huanghemi and decreased for Elizabeth. Elizabeth registered 22 µmol m-2 s-1 for light compensation and 1127 µmol m-2 s-1 for light saturation, which, respectively, were 50 and 70% of those required by Huanghemi. The Pn increased with increasing leaf temperatures in the range of 9.8 to 50.8°C. The optimum temperature for photosynthesis was 35.3°C for muskmelon grown in open field, 2.4°C (7%) greater than that for muskmelon grown in the greenhouse. At optimal temperatures, the field-grown muskmelon had the Pn of 19.8 µmol m-2 s-1, 30% greater than that for the greenhouse-grown muskmelon. Both cultivars responded positively to CO2 concentrations of below the CO2 saturation points, whereas Huanghemi exhibited greater (51%) Pn and higher (49%) carboxylation efficiency than Elizabeth at optimal CO2 level. The two cultivars exhibited greater photosynthesis in open field than when grown in solar-heated greenhouses, while Elizabeth performed better than Huanghemi when light conditions were poor. Selective use of cultivars with low requirements for light and temperatures will enhance the photosynthesis and productivity of muskmelon grown in solar-heated greenhouses of northwest China. Key words: Light compensation, light saturation, photon flux density, transpiration

Responses of Rainforest Understorey Plants to Excess Light during Sunflecks

1997 ◽  
Vol 24 (1) ◽  
pp. 17 ◽  
Author(s):  
Jenny R. Watling ◽  
Sharon A. Robinson ◽  
Ian E. Woodrow ◽  
C. Barry Osmond
Keyword(s):  
Tropical Rainforest ◽  
Photon Flux ◽  
Photochemical Quenching ◽  
Photon Flux Density ◽  
Leaf Angle ◽  
Low Light ◽  
Fourth Species ◽  
Excess Light ◽  
Understorey Plants ◽  
Non Photochemical Quenching

Responses of Alocasia macrorrhiza (L.) G. Don, Castanospora alphandii (F. Muell.) F. Muell. and Alpinia hylandii R. Smith, growing in a tropical rainforest understorey, to excess light during sunflecks were investigated using chlorophyll fluorescence techniques and by analysing xanthophyll cycle activity. A fourth species, the pioneerOmalanthus novo-guineensis (Warb.) Schum., growing in a small gap, was also studied. In all three understorey species there were large and rapid decreases in the proportion of open Photosystem II (PSII) centres, as indicated by qP, on illumination with saturating light and a concurrent increase in non-photochemical quenching. qP remained low (< 0.4) throughout the period of illumination (~15 min), although it did increase gradually, probably reflecting photosynthetic induction. Sustained declines (up to 120 min) in quantum yield, indicated by Fv/Fm, occurred in all three understorey species following exposure to saturating Photon flux density (PFD) during sunflecks. When ?PSII was monitored during sunflecks it was found to be very sensitive to changes in PFD, declining rapidly with even modest rises in the latter. There was rapid and continuing net conversion of violaxanthin (V) to antheraxanthin plus zeaxanthin (A+Z) on exposure of A. macrorrhiza and C. alphandii to saturating sunflecks. On returning to low light A. macrorrhiza retained its high levels of A+Z for up to 60 min, while C. alphandii rapidly converted back to V. O. novo- guineensis responded to high light by changing its leaf angle to reduce interception and showed no indication of photoinhibition during or after exposure.

scholarly journals Promotive effects of 5-aminolevulinic acid on photosynthesis and chlorophyll fluorescence of tomato seedlings under suboptimal low temperature and suboptimal photon flux density stress – Short communication

2012 ◽  
Vol 39 (No. 2) ◽  
pp. 97-99 ◽  
Author(s):  
Guo Xiaoqing ◽  
Li Yansu ◽  
Yu Xianchang
Keyword(s):  
Flux Density ◽  
Short Communication ◽  
Transformation Efficiency ◽  
Aminolevulinic Acid ◽  
Compensation Point ◽  
Photon Flux ◽  
Photochemical Quenching ◽  
Photon Flux Density ◽  
Tomato Seedlings ◽  
Maximum Quantum Efficiency

Effects of 5-aminolevulinic acid (ALA) on photosynthetic characteristics of tomato grown under suboptimal conditions were investigated to evaluate the potential value of ALA spraying in vegetables. The net photosynthetic rate (Pn), stomatal conductance (Gs), maximum quantum efficiency of photosystem II (Fv/Fm), coefficient of photochemical quenching (qP), antenna transformation efficiency (Fv'/Fm'), light compensation point (LCP), CO<sub>2 </sub>compensation point (CCP) and chlorophyll (chl) contents of tomato stressed by suboptimal temperature (17&deg;C/12&deg;C) and suboptimal photon flux density (250 &mu;mol/m<sup>2</sup>s) were decreased, but intercellular CO<sub>2 </sub>concentration (Ci) was increased distinctly. Compared with the parameters of tomato pretreated with water, Pn, Gs, Fv/Fm, qP, Fv'/Fm' and chl content of tomato pretreated with ALA were increased, and the Ci, LCP and CCP were decreased obviously. These results indicate that the inhibition of photosynthesis induced by suboptimal stress can be alleviated by ALA spraying.

Photosynthetic and fluorescence light responses for kiwifruit (Actinidia deliciosa) leaves at different stages of development on vines grown at two different photon flux densities

2001 ◽  
Vol 28 (5) ◽  
pp. 373 ◽  
Author(s):  
Dennis H. Greer ◽  
Elizabeth A. Halligan
Keyword(s):  
Electron Transport ◽  
Maximum Rate ◽  
High Capacity ◽  
Actinidia Deliciosa ◽  
Thermal Dissipation ◽  
Photon Flux ◽  
Photochemical Quenching ◽  
Fluorescence Light ◽  
Low Efficiency ◽  
Non Photochemical Quenching

Potted kiwifruit, Actinidia deliciosa [(A.Chev.) C.F.Liang et A.R.Ferguson], vines were grown at two controlled photon flux densities (PFD) of 250 and 1100 mol m–2 s–1 for 110 d to examine ontogenetic and PFD responses of photosynthesis. Oxygen evolution of detached leaf disks and PFD responses of both photosynthesis and chlorophyll fluorescence of attached leaves were measured. A range of leaves, at different nodal positions on the vines, were used and measurements were repeated over time on the same leaves as they expanded. Results showed that PFD responses of photosynthesis of the high- and low-PFD-grown vines are typical for sun/shade differentiation in Pmax and in the PFD for light saturation. The low-PFD-grown vines saturated at a PFD of 680 mol m–2 s–1 and had a mean maximum rate of 12.0 mol m–2 s–1 while high-PFD-grown vines saturated at 960 mol m–2 s–1, with a mean maximum rate of 15.2 mol m–2 s–1. There were similar differences between the two growth regimes in the electron transport rate (ETR) but non-photochemical quenching (NPQ) was higher in the low than in the high-PFD-grown vines. Young expanding leaves were characterised by low efficiency of both photochemistry and photosynthesis, low capacity for both electron transport through photosystem II and CO2 fixation capacity but by high respiration and a high capacity for non-radiative thermal dissipation. When the leaves had fully expanded, there were marked shifts towards higher photon yields, ETR and Pmax and low respiration and NPQ. In comparison with the effects of growth PFD, ontogenetic effects on development of photosynthetic competence had greater influences on the PFD responses of photochemistry and photosynthesis.

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