Variation In Chlorophyll Fluorescence Research Articles

Addressing the altitudinal and geographical gradient in European beech via photosynthetic parameters: a case study on Calabrian beech transplanted to Denmark

European beech (Fagus sylvatica L.) is becoming one of the go-to species in reconstructing declining conifer stands in Europe under climate change. Assisted migration may be considered when looking for suitable beech seedlings. Knowledge about the photosynthetic performance of beech seedlings is fundamental to understanding an essential part of their growth and survival potential in different planting conditions. We investigated the within-provenance variation in photosynthetic performance driven by altitude in contrast to inter-provenance variation given by geographical distance. The experiment was conducted on seedlings replanted in a Danish common garden comprising a cluster of provenances with various altitudinal subgroups transplanted from the Calabria region (Italy) and two local Danish provenances. Provenance and within-provenance variation in chlorophyll fluorescence (ChlF) kinetics, gas exchange (GE), flushing, and senescence were assessed. ChlF measurements revealed within-provenance differences based on altitude of origin and could distinguish between the two Danish provenances. In contrast, GE parameters detected variation in the geographical distance among Italian provenances. High-elevation subgroups of Italian provenances showed the best leaf-level photosynthetic performance in Danish weather conditions with high precipitation levels. Altitude of origin can be a significant source of within-provenance variation. We demonstrated that assessing this variation in young trees may be instrumental in maximizing the potential of provenance variation across diverse planting sites.

Fertilization and seasonality influence on the photochemical performance of tree legumes in forest plantation for area recovery in the Amazon.

N-fixing leguminous species can reach atmospheric dinitrogen gas (N2), having an advantage under N-limited degraded environments. These N-fixers are constantly used as facilitative species. Chlorophyll a fluorescence (ChF) acknowledges how different species take up and use light energy during photosynthesis. These techniques assess stress and performance responses to photosynthesis and are used for the selection of species with potential for reforestation. Six Fabaceae species were selected for this study: three nonfixing species (Cenostigma tocantinum, Senna reticulata and Dipteryx odorata) and three N-fixing species (Clitoria fairchildiana, Inga edulis and Acacia spp.). Variations in chlorophyll fluorescence under high vs. low water and nutrient conditions were studied. Multivariate analysis was performed to detect the effects of seasonality and fertilization on dark-adapted ChF two years after the experiment was established. The correlation among ChF variables and growth, photosynthesis and foliar nutrient concentrations was evaluated. Under high water- and nutrient-availability conditions, plants exhibited an enhanced performance index on absorption basis values correlated with electron transport fluxes. Under drought and nutrient-poor conditions, most species exhibit increased energy dissipation as photoprotection. High interspecific variation was found; therefore, species-specific responses should be considered in future ChF studies. Corroborating the ability to colonize high-light environments, N-fixers showed an increased performance index correlated with electron transport and Zn and N foliar concentrations. Negative correlations were found between photosynthesis and trapped fluxes. Diameter growth was positively correlated with electron transport fluxes. Given the different responses among species, ChF is an effective technique to screen for seasonality, fertilization and species effects and should be considered for use during forest restoration. Finally, the addition of fertilization treatments may facilitate tropical forest restoration due to the importance of nutrients in physiological processes. N-fixers showed high photochemical performance and tolerance to abiotic stress in degraded areas and therefore should be included to support ecosystem biomass restoration.

Diurnal and Seasonal Variations in Chlorophyll Fluorescence Associated with Photosynthesis at Leaf and Canopy Scales

There is a critical need for sensitive remote sensing approaches to monitor the parameters governing photosynthesis, at the temporal scales relevant to their natural dynamics. The photochemical reflectance index (PRI) and chlorophyll fluorescence (F) offer a strong potential for monitoring photosynthesis at local, regional, and global scales, however the relationships between photosynthesis and solar induced F (SIF) on diurnal and seasonal scales are not fully understood. This study examines how the fine spatial and temporal scale SIF observations relate to leaf level chlorophyll fluorescence metrics (i.e., PSII yield, YII and electron transport rate, ETR), canopy gross primary productivity (GPP), and PRI. The results contribute to enhancing the understanding of how SIF can be used to monitor canopy photosynthesis. This effort captured the seasonal and diurnal variation in GPP, reflectance, F, and SIF in the O2A (SIFA) and O2B (SIFB) atmospheric bands for corn (Zea mays L.) at a study site in Greenbelt, MD. Positive linear relationships of SIF to canopy GPP and to leaf ETR were documented, corroborating published reports. Our findings demonstrate that canopy SIF metrics are able to capture the dynamics in photosynthesis at both leaf and canopy levels, and show that the relationship between GPP and SIF metrics differs depending on the light conditions (i.e., above or below saturation level for photosynthesis). The sum of SIFA and SIFB (SIFA+B), as well as the SIFA+B yield, captured the dynamics in GPP and light use efficiency, suggesting the importance of including SIFB in monitoring photosynthetic function. Further efforts are required to determine if these findings will scale successfully to airborne and satellite levels, and to document the effects of data uncertainties on the scaling.

Temporal variation in chlorophyll fluorescence of different tree species

ABSTRACTIn the present work, an attempt has been made to observe the temporal variation in leaf chlorophyll fluorescence of different tree species (Madhuca longifolia, Ricinus communis and Terminalia arjuna). Leaf chlorophyll fluorescence parameters viz. Fv/Fm = Fm−Fo/Fm (maximum photochemical quantum yield of photosystem II), Y (II) = F’m−F’/F’m (photochemical quantum yield of photosystem II) and qL = qp.F0ʹ/F’ (coefficient of photochemical fluorescence quenching) of above trees were recorded at different daytimes with the help of JUNIOR‐PAM, Chlorophyll Fluorometer, Heinz Walz GmbH, Germany. It was found that above parameters showed clear-cut temporal variations of leaf chlorophyll fluorescence in all the species. Y (II) and qL showed similar temporal variation patter, while Fv/Fm showed opposite variation as compared to Y (II) and qL.

Growth responses of Atriplex lentiformis and Medicago arborea in three soil types treated with saline water irrigation

Large amounts of industrial wastewater, often of high in salt content, are produced by urban activities or industries which require reuse or disposal and thus can be potentially used in agriculture to ease the pressure on freshwater supply for irrigation. At the same time, plant performance in the field may be determined not only by salt concentration per se but also by confounding effects associated with soil physical and chemical properties. The purpose of this study was to investigate the effect of saline water irrigation (0–16dS/m range) on the performance of two plant species, Atriplex lentiformis (xero halophyte) and Medicago arborea (glycophyte) grown in three soil texture setups – (1) clay, (2) sandy loam and (3) sandy loam over clay (texture-contrast) – under glasshouse conditions. Both plant species yielded higher biomass in the clay texture compared to other soil texture setups under all irrigation treatments. There was no significant variation in chlorophyll fluorescence with salt treatments but stomatal conductance was significantly reduced (up to 70%) by salinity in M. arborea. Overall, leaf ion content (Na+ and Cl−) also increased with increasing salinity treatment in both plants, but significant effects were seen only in sandy loam soil for both species. Both osmotic effect and specific ionic toxicity impacted physiological performance in M. arborea while A. lentiformis plants were insensitive to both components of salt stress. Plant performance in the sandy soil was not as good as in clay, indicating that soil texture and structure may have a significant role in the salt stress process under saline irrigation.

Screening for Barley Waterlogging Tolerance in Nordic Barley Cultivars (Hordeum vulgare L.) Using Chlorophyll Fluorescence on Hydroponically-Grown Plants

Waterlogging can reduce crop yield by 20%–50% or more, and lack of efficient selection methods is an obstacle in plant breeding. The methods currently used are mainly indices based on germination ability in Petri dishes and leaf chlorosis in plants grown in waterlogged soils. Cultivation in oxygen-depleted nutrient solution is the ultimate waterlogging system. Therefore methods based on root growth inhibition and on fluorescence in plant material hydroponically grown in oxygen-depleted solution were evaluated against data on biomass accumulation in waterlogged soils. Both traits were correlated with waterlogging tolerance in soil, but since it was easier to measure fluorescence, this method was further evaluated. A selection of F2 plants with high and low fluorescence revealed a small but significant screening effect in F3 plants. A test of 175 Nordic cultivars showed large variations in chlorophyll fluorescence in leaves from oxygen-stressed seedlings, indicating that adaptation to waterlogging has gradually improved over the past 40–50 years with the introduction of new cultivars onto the market. However, precipitation also increased during the period and new cultivars may have inadvertently been adapted to this while breeding barley for grain yield. The results suggest that the hydroponic method can be used for screening barley populations, breeding lines or phenotyping of populations in developing markers for quantitative trait loci.

Diurnal variation in chlorophyll fluorescence of Thalassia testudinum seedlings in response to controlled salinity and light conditions

Diurnal variability in chlorophyll fluorescence caused by dynamic irradiance conditions is an important issue when using pulse amplitude modulation fluorometry to measure physiological conditions of plants at the landscape scale. We examined the use of slopes and y-intercepts of diurnal effective photochemical efficiency of photosystem II (PSII) (ΔF/F m′) versus photosynthetically active radiation (PAR) regressions in addition to direct measurements of maximum photochemical efficiencies of PSII (F v/F m) values to assess physiological status of Thalassia testudinum seedlings in a controlled mesocosm study. Seedlings were exposed to two light treatments (full sun and 50–70 % light reduction) and three salinity treatments (20, 35, and 50). Measurements were taken at 0600, 0900, 1200, 1500, 1800, and 2100 hours in order to assess the diurnal variation in photochemical efficiency of PSII and PAR, with measurements at 2100 providing F v/F m. Results indicated significant effects of light and salinity on regression y-intercepts and measured F v/F m values. Shaded seedlings had higher values for both parameters, suggesting low-light acclimation. The highest salinity treatment resulted in significant reductions for both parameters, suggesting stress. Stress was also indicated by significant reductions in both seedling leaf growth and mean differences between seedling leaves and media osmolalities in the hypersaline treatments (152.0 ± 26.4 vs. 630 ± 40.2 mmol kg−1 for the control treatments). Slopes of ΔF/F m′ versus PAR significantly differed with varying light treatments, with full sun seedlings exhibiting shallower slopes than shaded seedlings, indicating higher efficiency of dissipation of excess energy (photoprotection). These experimental results confirm field data suggesting that diurnal ΔF/F m′ versus PAR regressions are responsive to changes in the physiological status of T. testudinum and that the y-intercepts of diurnal regressions may be used as a proxy for F v/F m.

Definition and Evaluation of the Spatio‐Temporal Variations in Chlorophyll Fluorescence during the Phases of CAM and during Endogenous Rhythms in Continuous Light, in Thick Leaves of Kalanchoë daigremontiana5

Abstract: We used chlorophyll fluorescence imaging to examine the homogeneity of photosynthetic metabolism during CAM in the thick leaves of Kalanchoë daigremontiana Hamet et Perrier de la Bǎthie. Intense, persistent fluorescence from a DCMU treated thin leaf of Clematis sp placed beneath a K. daigremontiana leaf was readily detected through the thick leaf. Evidently reabsorption of fluorescence was qualitatively unimportant in the system used. Chlorophyll fluorescence images from 7 mm tissue discs excised from Kalanchoë leaves were collected at 60 s intervals during 20 min transients elicited by red excitation light. Information about patchiness and subsurface processes was gained by statistical factor analysis and Fourier transform. Although small, highly resolved rings of bright chlorophyll fluorescence surrounding discs of low fluorescence were observed from cells near the surface, no independent regional temporal variation in fluorescence was evident in the surface‐biased images. Temporally independent chlorophyll fluorescence was present in images biased towards sub‐epidermal sources, in most phases of CAM, and during endogenous rhythm. These asynchronous changes were several millimetres apart. This patchy fluorescence was confirmed when attached leaves were excited with blue light in a leaf chamber while CO2 and H2O exchange was monitored. Large spatio‐temporal variations in the efficiency of photosystem II were always observed during phases II and IV of CAM, when both CO2 fixation cycles are active, and during the maximum rate of CO2 fixation during the endogenous rhythm in continuous light. These data are discussed in terms of metabolic isolation in the thick but uniform tissues in which gas diffusion may be largely confined to wet cell walls, thereby rendering the tissue functionally heterobaric. Prolonged, but in some instances, reversible alterations in PSII efficiency could be produced by injection of metabolic inhibitors, confirming that patchy fluorescence may reflect the differing energy costs of photosynthesis in different CAM phases.

Diurnal and Seasonal Variations in Chlorophyll a Fluorescence in Two Mediterranean-Grassland Species Under Field Conditions

Seasonal and daily variations in chlorophyll (Chl) fluorescence were studied in two representative species of Mediterranean grasslands, Tuberaria guttata (an annual) and Chamaemelum nobile (a perennial), in order to assess physiological responses to climatically induced stresses during the growing season. The photochemical efficiency of photosystem (PS) 2 in dark-adapted leaves was measured by the Chl fluorescence ratio Fv/Fp. This ratio decreased progressively from December to July, as the effects of increasing solar radiation and summer drought became more severe. The seasonal decline was observed particularly as a depression of morning and midday values, when photoinhibition was more evident. In both species, the extent of this diurnal depression increased with midday irradiance throughout winter and spring. After sunset, there was complete recovery to optimum values. Towards the end of the life cycle, increased irradiance did not affect the midday decline further but Fv/Fp measurements in the morning and evening never regained their optimum values, indicating the accumulation of photodamage in the reaction centres of PS2. The half-rise time of Fp (T1/2), used to estimate the size of the plastoquinone pool, showed little daily variation in C. nobile throughout the most important part of its seasonal cycle. However, towards the end of its life cycle (June and July) T1/2 values ranged from ca. 200 ms before sunrise to near zero at midday on the same day. The annual species, T. guttata, showed similar disregulation in energy transmission rate both at the seedling stage and at end of its life cycle. Thus seedlings and reproductive plants in particular are sensitive to environmental conditions (extremes of temperature and drought) and cannot maintain consistent electron flow throughout the day.

Genetic Variations in Chlorophyll Fluorescence, Photosynthesis, and Carbon Partitioning into Sorbitol, Sucrose, and Starch in Apple Leaves

Chlorophyll fluorescence measurements are providing insights into Photosystem II (PSII) quantum efficiency and hence are able to provide a good estimation of carbon assimilation under field conditions. A F2 generation of sibcross seedlings from a cross of `Goldspur' × `Redspur' were selected to identify genetic variations and the relationships among fluorescence parameters, carbon assimilation, and carbon partitioning in apple leaves. Mature leaves from extension shoots were analyzed for chlorophyll fluorescence with a CF-1000 chlorophyll fluorescence measurement system, photosynthetic rate with a LI-6200 portable photosynthesis system, and carbohydrates with a Shimadzu HPLC. Significant variations in leaf chlorophyll fluorescence parameters and photosynthetic rates were found. The ratio of Fv: Fm, an estimation of photochemical efficiency of PSII, decreased from ≈0.90 in June to ≈0.75 in September while the photosynthetic rates decreased from ≈8.5 in June to ≈4.5 μmol·m–2·s–l in September. The relationships between fluorescence parameters, photosynthesis, and carbohydrate partitioning were analyzed and the ratio of sorbitol to sucrose in relation to the efficiency of PSII and NADPH production will be discussed.

Photoinhibition of photosynthesis in intact kiwifruit (Actinidia deliciosa) leaves: Changes in susceptibility to photoinhibition and recovery during the growth season

Kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson) plants grown in an outdoor enclosure were exposed to the natural conditions of temperature and photon flux density (PFD) over the growing season (October to May). Temperatures ranged from 14 to 21° C while the mean monthly maximum PFD varied from 1000 to 1700 μmol · m(-2) · s(-1), although the peak PFDs exceeded 2100 μmol · m(-2) · s(-1). At intervals, the daily variation in chlorophyll fluorescence at 692 nm and 77K and the photon yield of O2 evolution in attached leaves was monitored. Similarly, the susceptibility of intact leaves to a standard photoinhibitory treatment of 20° C and a PFD of 2000 μmol · m(-2) · s(-1) and the ability to recover at 25° C and 20 μmol · m(-2) · s(-2) was followed through the season. On a few occasions, plants were transferred either to or from a shade enclosure to assess the suceptibility to natural photoinhibition and the capacity for recovery. There were minor though significant changes in early-morning fluorescence emission and photon yield throughout the growing season. The initial fluorescence, Fo, and the maximum fluorescence, Fm, were, however, significantly and persistently different from that in shade-grown kiwifruit leaves, indicative of chronic photoinhibition occurring in the sun leaves. In spring and autumn, kiwifruit leaves were photoinhibited through the day whereas in summer, when the PFDs were highest, no photoinhibition occurred. However, there was apparently no non-radiative energy dissipation occurring then also, indicating that the kiwifruit leaves appeared to fully utilize the available excitation energy. Nevertheless, the propensity for kiwifruit leaves to be susceptible to photoinhibition remained high throughout the season. The cause of a discrepancy between the severe photoinhibition under controlled conditions and the lack of photoinhibition under comparable, natural conditions remains uncertain. Recovery from photoinhibition, by contrast, varied over the season and was maximal in summer and declined markedly in autumn. Transfer of shade-grown plants to full sun had a catastrophic effect on the fluorescence characteristics of the leaf and photon yield. Within 3 d the variable fluorescence, Fv, and the photon yield were reduced by 80 and 40%, respectively, and this effect persisted for at least 20 d. The restoration of fluorescence characteristics on transfer of sun leaves to shade, however, was very slow and not complete within 15 d.

MECHANISMS OF RAPID PHOTOSYNTHETIC ADAPTATION IN NATURAL PHYTOPLANKTON COMMUNITIES. I. REDISTRIBUTION OF EXCITATION ENERGY BETWEEN PHOTOSYSTEMS I AND II1

ABSTRACTAn inverse linear relationship between chlorophyll fluorescence yield (R) and light intensity was recorded in the near‐surface waters of six lakes (New Zealand, England) of greatly different trophic status and phytoplankton species composition. This surface depression of R values could be removed by incubation of samples in dim light or darkness and was not observed in situ below a threshold irradiance (146 μEin ·m−2·s−1 for Lake Taupo, New Zealand). The time course of chlorophyll fluorescence depression and recovery in response to light treatment was measured in samples from Lake Windermere (England). Fluorescence exponentially decreased upon exposure to bright light and the response was 100% (5 m samples) or 83% (dim light‐adapted 0 m samples) complete within 2 min. An increase in R values in the dim light occurred after a lag of 60 s and the rate of increase decreased exponentially with time. Full recovery took 15 min or more. Deep (6.5 m) populations from Lake Windermere exhibited large, time‐dependent variations in chlorophyll fluorescence over the first 25 s of exposure to 450 nm light, whereas surface populations did not. These data were interpreted in terms of decreased spillover from PSII to PSI with increasing depth, to a minimum at the threshold light intensity below which cells are in light state 1.