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.

Phosphate Deficiency Increases the Rate Constant of Thermal Dissipation of Excitation Energy by Photosystem II in Intact Leaves of Sunflower and Maize.

1995 ◽  
Vol 22 (3) ◽  
pp. 417 ◽  
Author(s):  
J Jacob
Keyword(s):  
Excitation Energy ◽  
Rate Constant ◽  
Thermal Dissipation ◽  
Phosphate Deficiency ◽  
Photon Flux ◽  
Photochemical Quenching ◽  
Variable Fluorescence ◽  
Psii Photochemistry ◽  
Non Photochemical Quenching

Sunflower (Helianthus annuus L.) and maize (Zea mays L.) plants were grown in controlled environment chambers either with adequate supply or no external supply of inorganic phosphate. On the third fully-expanded leaves, chlorophyll fluorescence from photosystem II (PSII) was measured using a modulated fluorescence measuring system at various photon flux densities at room temperature. Phosphate deficiency resulted in an increase in the coefficient of non-photochemical quenching and a decrease in the coefficient of photochemical quenching of variable fluorescence. The efficiency of excitation energy capture by open PSII reaction centres and quantum yield of PSII photochemistry were decreased with phosphate deficiency. There was a significant effect of phosphate deficiency on in vivo PSII photochemistry which was independent of changes in thylakoid membrane energisation induced by the actinic light. An increase in the non-photochemical quenching of variable fluorescence with phosphate deficiency was due to an increased rate constant of thermal dissipation of excitation energy by PSII. Analyses of fluorescence signals suggest that phosphate deficiency decreased the rate constant of PSII photochemistry as well as the probability of excitation energy transfer from PSII antenna to PSII reaction centre. These effects were more apparent at low photon flux densities than at high photon flux densities. Regulation of energy transduction in the thylakoid and in vivo PSII activity in response to the physical environment of the plant are important aspects of environmental regulation of photosynthesis.

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.

Light Absorption and Partitioning in Response to Nitrogen in Apple Leaves

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 541a-541
Author(s):  
Lailiang Cheng ◽  
Leslie H. Fuchigami ◽  
Patrick J. Breen
Keyword(s):  
High Light ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Light Conditions ◽  
Psii Efficiency ◽  
Fluorescence Measurements ◽  
Free Radical Formation ◽  
Highly Correlated ◽  
Non Photochemical Quenching ◽  
Leaf N

Bench-grafted Fuji/M26 apple trees were fertigated with different concentrations of nitrogen by using a modified Hoagland solution for 6 weeks, resulting in a range of leaf N from 1.0 to 4.3 g·m–2. Over this range, leaf absorptance increased curvilinearly from 75% to 92.5%. Under high light conditions (1500 (mol·m–2·s–1), the amount of absorbed light in excess of that required to saturate CO2 assimilation decreased with increasing leaf N. Chlorophyll fluorescence measurements revealed that the maximum photosystem II (PSII) efficiency of dark-adapted leaves was relatively constant over the leaf N range except for a slight drop at the lower end. As leaf N increased, non-photochemical quenching under high light declined and there was a corresponding increase in the efficiency with which the absorbed photons were delivered to open PSII centers. Photochemical quenching coefficient decreased significantly at the lower end of the leaf N range. Actual PSII efficiency increased curvilinearly with increasing leaf N, and was highly correlated with light-saturated CO2 assimilation. The fraction of absorbed light potentially used for free radical formation was estimated to be about 10% regardless of the leaf N status. It was concluded that increased thermal dissipation protected leaves from photo-oxidation as leaf N declined.

scholarly journals Photosynthesis Regulation in Response to Fluctuating Light in the Secondary Endosymbiont Alga Nannochloropsis gaditana

2019 ◽  
Vol 61 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Alessandra Bellan ◽  
Francesca Bucci ◽  
Giorgio Perin ◽  
Alessandro Alboresi ◽  
Tomas Morosinotto
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Incident Light ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Nannochloropsis Gaditana ◽  
Fluctuating Light ◽  
Light Fluctuations

Abstract In nature, photosynthetic organisms are exposed to highly dynamic environmental conditions where the excitation energy and electron flow in the photosynthetic apparatus need to be continuously modulated. Fluctuations in incident light are particularly challenging because they drive oversaturation of photosynthesis with consequent oxidative stress and photoinhibition. Plants and algae have evolved several mechanisms to modulate their photosynthetic machinery to cope with light dynamics, such as thermal dissipation of excited chlorophyll states (non-photochemical quenching, NPQ) and regulation of electron transport. The regulatory mechanisms involved in the response to light dynamics have adapted during evolution, and exploring biodiversity is a valuable strategy for expanding our understanding of their biological roles. In this work, we investigated the response to fluctuating light in Nannochloropsis gaditana, a eukaryotic microalga of the phylum Heterokonta originating from a secondary endosymbiotic event. Nannochloropsis gaditana is negatively affected by light fluctuations, leading to large reductions in growth and photosynthetic electron transport. Exposure to light fluctuations specifically damages photosystem I, likely because of the ineffective regulation of electron transport in this species. The role of NPQ, also assessed using a mutant strain specifically depleted of this response, was instead found to be minor, especially in responding to the fastest light fluctuations.

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 Photoprotective Mechanisms of Grape Leaves (Vitis labrusca L. cv. Concord) in Relation to Iron Supply

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 854A-854
Author(s):  
Brandon Smith* ◽  
Lailiang Cheng
Keyword(s):  
Beta Carotene ◽  
Thermal Dissipation ◽  
Monodehydroascorbate Reductase ◽  
Photochemical Quenching ◽  
Vitis Labrusca ◽  
Fe Content ◽  
Hydroxyphenylacetic Acid ◽  
Antioxidant Metabolites ◽  
One Year ◽  
Non Photochemical Quenching

One-year-old `Concord' grapevines (Vitis labrusca L.) were fertigated twice weekly for 11 weeks with a complete nutrient solution containing 1, 10, 20, 50 or 100 μmol iron (Fe) from ferric ethylenediamine di (o-hydroxyphenylacetic) acid (Fe-EDDHA). Leaf total Fe content did not increase in response to Fe supply, however both “active” Fe (extracted with 2, 2'-dipyridyl) and chlorophyll (Chl) content increased as applied Fe increased. At the lowest active Fe level, leaf absorptance and maximum PSII efficiency (Fv/Fm) were slightly decreased, and non-photochemical quenching was significantly greater. PSII quantum efficiency decreased curvilinearly as active Fe content decreased. On a Chl basis, the xanthophyll cycle pool size, lutein, and beta-carotene increased curvilinearly as active Fe decreased, and neoxanthin increased at the lowest Fe level. Activities of antioxidant enzymes superoxide dismutase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase followed a similar trend and increased under Fe deficiency, when expressed on a Chl basis. Antioxidant metabolites also increased in response to Fe limitation. On a Chl basis, ascorbate (AsA), dehydroascorbate (DAsA), reduced glutathione (GSH) and oxidized glutathione (GSSG) content was greater at the lowest active Fe levels. We did not find a difference in the ratio of AsA to DAsA or GSH to GSSG. In conclusion, both photoprotective mechanisms, xanthophyll cyle-dependent thermal dissipation and the ascorbate-glutatione antioxidant system, are enhanced in response to iron deficiency to cope with excess absorbed light.

scholarly journals The JcWRKY tobacco transgenics showed improved photosynthetic efficiency and wax accumulation during salinity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Prashant More ◽  
Parinita Agarwal ◽  
Priyanka S. Joshi ◽  
Pradeep K. Agarwal
Keyword(s):  
Electron Transport ◽  
Photosynthetic Efficiency ◽  
Crop Productivity ◽  
Major Constituent ◽  
Photochemical Quenching ◽  
Subtle Effect ◽  
Cellular Reactive Oxygen Species ◽  
Photosynthesis Efficiency ◽  
Major Factors ◽  
Non Photochemical Quenching

AbstractSalinity is one of the major factors negatively affecting crop productivity. WRKY transcription factors (TFs) are involved in salicylic acid (SA) mediated cellular reactive oxygen species homeostasis in response to different stresses, including salinity. Therefore, the effect of NaCl, NaCl + SA and SA treatments on different photosynthesis-related parameters and wax metabolites were studied in the Jatropha curcas WRKY (JcWRKY) overexpressing tobacco lines. JcWRKY transgenics showed improved photosynthesis rate, stomatal conductance, intercellular CO2 concentration/ambient CO2 concentration ratio (Ci/Ca ratio), electron transport rate (ETR), photosynthesis efficiency (Fv/Fm), photochemical quenching (qP), non-photochemical quenching (NPQ) and quantum yield of PSII electron transport (ΦPSII) in response to salinity stress, while exogenous SA application had subtle effect on these parameters. Alkane, the major constituent of wax showed maximum accumulation in transgenics exposed to NaCl. Other wax components like fatty alcohol, carboxylic acid and fatty acid were also higher in transgenics with NaCl + SA and SA treatments. Interestingly, the transgenics showed a higher number of open stomata in treated plants as compared to wild type (WT), indicating less perception of stress by the transgenics. Improved salinity tolerance in JcWRKY overexpressing tobacco transgenics is associated with photosynthetic efficiency and wax accumulation, mediated by efficient SA signalling. The transgenics showed differential regulation of genes related to photosynthesis (NtCab40, NtLhcb5 and NtRca1), wax accumulation (NtWIN1) and stomatal regulation (NtMUTE, NtMYB-like, NtNCED3-2 and NtPIF3). The present study indicates that JcWRKY is a potential TF facilitating improved photosynthesis with the wax metabolic co-ordination in transgenics during stress.

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