scholarly journals Consequences of Injury Caused by Cameraria caryaefoliella (Lepidoptera: Gracillariidae) on Pecan Gas Exchange and Chlorophyll Fluorescence

2013 ◽  
Vol 138 (4) ◽  
pp. 263-266
Author(s):  
Leonardo Lombardini ◽  
Astrid Volder ◽  
Monte L. Nesbitt ◽  
Donita L. Cartmill
Keyword(s):  
Chlorophyll Fluorescence ◽  
Gas Exchange ◽  
Photosynthetic Efficiency ◽  
Photosynthetic Apparatus ◽  
Carbon Assimilation ◽  
Strong Relationship ◽  
Carya Illinoinensis ◽  
Assimilation Rate ◽  
Compensatory Increase ◽  
Injured Area

After an outbreak of blotch leafminer (Cameraria caryaefoliella) on field-grown pecan (Carya illinoinensis) trees in 2010, an experiment was conducted to evaluate the consequences of the injury on carbon assimilation and photosynthetic efficiency, and, in particular, to assess if low-to-moderate injury induces a compensatory increase in photosynthesis. Gas exchange and light-adapted fluorescence were measured on non-injured portions of the leaflet lamina adjacent to the injured area as well as on portions of leaflets that included leafminer injury. Results indicate that damage of the photosynthetic apparatus did not extend beyond the injured areas by leafminers. Furthermore, although a strong relationship between the proportion of leafminer injury and area-based net CO2 assimilation rate of injured leaflet tissue was found, there was no evidence that pecan leaves were able to compensate for leafminer injury by upregulating CO2 assimilation in leaflet tissue that was unaffected.

Simultaneous Gas-Exchange and Fluorescence Measurements with Ozone-Fumigated Spruce

1994 ◽  
Vol 49 (11-12) ◽  
pp. 819-833
Author(s):  
Stefan Drenkard ◽  
Jürgen Maguhn ◽  
Dietmar Knoppik
Keyword(s):  
Gas Exchange ◽  
Calvin Cycle ◽  
Photosynthetic Apparatus ◽  
Early Summer ◽  
Assimilation Rate ◽  
Light Reaction ◽  
Fluorescence Measurements ◽  
Transport Chain ◽  
Short Time ◽  
Supply Information

A method was developed for carrying out gas-exchange and chlorophyll-fluorescence measurements simultaneously during fumigation of spruce twigs with peroxidic photooxidants. It is thus now possible to investigate how a pollutant affects distinct sectors of the photosynthetic apparatus of the plant: whereas fluorescence reveals any changes in the primary light reaction, CO2 gas-exchange measurements supply information about the biochemical reactions of the Calvin cycle. Results of short-time fumigation with 750 ppb ozone are presented here. Gas-exchange and fluorescence data are affected strongly in early summer, but not in autumn. The assimilation rate decreases significantly: primarily as a result of Rubisco activity and possibly because of direct inhibition of the electron-transport chain as well. Closure of the stomata leads to further reduction in the assimilation rate. Though no damage becomes visible on the needles, the perturbance of the photosynthetic apparatus caused by ozone fumigation is not reversible within 24 h.

Physiological performance of a foliose macrolichen Umbilicaria antarctica as affected by supplemental UV-B treatment

2015 ◽  
Vol 5 (2) ◽  
pp. 222-229 ◽  
Author(s):  
Mariana Gonzalez Medina ◽  
Roxana Avalos-Chacon
Keyword(s):  
Chlorophyll Fluorescence ◽  
High Resistance ◽  
Photosynthetically Active Radiation ◽  
High Intensity ◽  
Photosynthetic Efficiency ◽  
Photosynthetic Apparatus ◽  
Ps Ii ◽  
Fluorescence Kinetics ◽  
Active Radiation ◽  
High Doses

To date, a limited knowledge is available about Umbilicaria antarctica responses when it is exposed high doses of UV-B radiation. It is well established that resistance of Antarctic lichens to natural UV-B levels including increased doses during ozone hole period is high, thanks to numerous photoprotective mechanism. Capacity of the photoprotective processes, however, is not well known This study attempts to determine changes on the photosynthetic efficiency and on the synthesis of UV-B absorbing compounds of U. antarctica when exposed to low photosynthetically active radiation and extremely high intensity of UV-B light: 3.0 W m-2, of UV-B for 3 hours, 6 hours and 7 days. During the experiment, chlorophyll fluorescence was measured to evaluate changes in photosynthetic apparatus of intrathalline alga. After 7 d exposition, amount of UV-B absorbing compounds was evaluated in U. antarctica. Heavy UV-B stress let to an increase in chlorophyll fluorescence kinetics (OJIPs), however, majority of parameters related to functioning of PS II remained unchanged indicating high resistance of U. antarctica to UV-B stress. Potential (FV/FM) and actual (ФPSII) yields of PS II were not affected by the UV-B treatment as well. In majority of cases, heavy UV-B treatment led to a decrease in the amount of UV-B absorbing compounds extracted from treated thalli.

Measurements of the quantum yield of carbon assimilation and chlorophyll fluorescence for assessment of photosynthetic performance of crops in the field

1989 ◽  
Vol 323 (1216) ◽  
pp. 295-308 ◽  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Quantum Yield ◽  
Photosynthetic Apparatus ◽  
Fluorescence Emission ◽  
Carbon Assimilation ◽  
Growing Season ◽  
Photosynthetic Performance ◽  
Maize Crop ◽  
Fluorescence Kinetics ◽  
Light Energy Conversion

An apparatus is described for the rapid measurement in the field of the quantum yield of CO 2 assimilation, ø, and chlorophyll fluorescence kinetics from attached leaves exposed to ambient CO 2 concentrations. This apparatus was used to measure ø and the ratio of variable to maximal fluorescence, F v /F M , of fully expanded leaves of a maize crop in northeast Essex at monthly intervals throughout the growing season. The quantum yield of CO 2 assimilation and F v /F M increased from May to August and then decreased in September. A linear correlation between ø and F v /F M was observed for the leaves. The relations between light, temperature, the quantum yield of CO 2 assimilation and fluorescence emission kinetics of leaves of a maize crop during the early growing season were also examined. Decreases in ø associated with chilling temperatures and high light were observed and identified from analyses of fluorescence kinetics as being attributable to photoinhibitory damage of the photosynthetic apparatus. The possibility of using measurements of ø and fluorescence kinetics for screening the photosynthetic performance of crops is considered. Studies with winter rape demonstrated that changes in ø during the growing season were correlated with changes in the efficiency of light-energy conversion to dry matter by the crop.

scholarly journals Effects of Powdery Mildew of Grape on Carbon Assimilation Mechanisms of Potted `Chardonnay' Grapevines

HortScience ◽  
2004 ◽  
Vol 39 (7) ◽  
pp. 1670-1673 ◽  
Author(s):  
William R. Nail ◽  
G. Stanley Howell
Keyword(s):  
Chlorophyll Fluorescence ◽  
Stomatal Conductance ◽  
Powdery Mildew ◽  
Photochemical Efficiency ◽  
Carbon Assimilation ◽  
Compensation Point ◽  
Uncinula Necator ◽  
Assimilation Rate ◽  
Factors Affecting ◽  
Stomatal Limitations

Potted grapevines (Vitis vinifera L. `Chardonnay') were inoculated with conidial suspensions of the grapevine pathogen causing powdery mildew of grape (GPM) (Uncinula necator (Schw.) Burr.). Leaves of inoculated and noninoculated vines were studied for the effects of varying light (PAR) and CO2 concentrations on factors affecting carbon assimilation. GPM reduced carboxylation efficiency (k), net CO2 assimilation rate (A), stomatal conductance (gs), and internal CO2 concentration (Ci) under ambient CO2, Amax at >900 ppm CO2, stomatal limitations to A (lg), and photochemical efficiency (Φ) on diseased leaves, while having no effect on the CO2 compensation point (Γ) or the light compensation point (cp). GPM had no significant effect on chlorophyll fluorescence (Fv/Fm).

The Effect of Water Shortage on Potted Peach Trees in Relation to Ecophysiological Parameters and Infra-red Thermometry

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 541b-541
Author(s):  
Rita Giuliani ◽  
James A. Flore
Keyword(s):  
Chlorophyll Fluorescence ◽  
Gas Exchange ◽  
Early Detection ◽  
Water Potential ◽  
Canopy Temperature ◽  
Water Shortage ◽  
Development Rate ◽  
Plant Water ◽  
Infra Red ◽  
Peach Trees

Potted peach trees grown outdoors during the 1997 season were subjected to drought and subsequent rewatering to evaluate their dynamic response to soil water content. The investigation was primarily focused on the early detection of plant water stress to prevent negative effects on the growth. Leaf chlorophyll fluorescence and canopy temperature estimates (by infra-red thermometry) were conducted. Drought effect on physiological processes were detected through by estimates of canopy development rate, leaf gas-exchange measurements; while leaf water potential was measured to characterize plant water status. A decrease in the canopy's development rate was found 1 week after irrigation was stopped, which also coincided with a more-negative leaf water potential, whereas a decrease of the gas-exchange activities occurred several days later. No significant differences between the stressed and control plants were recorded by the chlorophyll fluorescence parameters (Fo, Fm, Fv and the ratio Fv/Fm), whereas the infra-red estimates of canopy temperature detected a slight increase of the canopy surface temperature (connected to the change of leaf energy balance and in relation to partial stomatal closure) on the non-irrigated plants 1 week after the beginning of the trial. The use of infra-red thermometry for early detection of water shortage is discussed.

Altitude of origin influences stomatal conductance and therefore maximum assimilation rate in Southern Beech, Nothofagus cunninghamii

2000 ◽  
Vol 27 (5) ◽  
pp. 451 ◽  
Author(s):  
Mark J. Hovenden ◽  
Tim Brodribb
Keyword(s):  
Stomatal Conductance ◽  
Stomatal Density ◽  
Carbon Assimilation ◽  
Co2 Concentration ◽  
Carboxylation Efficiency ◽  
Assimilation Rate ◽  
Carbon Assimilation Rate ◽  
Southern Beech ◽  
Maximum Stomatal Conductance ◽  
Leaf Biochemistry

Gas exchange measurements were made on saplings of Southern Beech, Nothofagus cunninghamii (Hook.) Oerst. collected from three altitudes (350, 780 and 1100 m above sea level) and grown in a common glasshouse trial. Plants were grown from cuttings taken 2 years earlier from a number of plants at each altitude in Mt Field National Park, Tasmania. Stomatal density increased with increasing altitude of origin, and stomatal con-ductance and carbon assimilation rate were linearly related across all samples. The altitude of origin influenced thestomatal conductance and therefore carbon assimilation rate, with plants from 780 m having a greater photosynthetic rate than those from 350 m. The intercellular concentration of CO2 as a ratio of external CO2 concentration (ci/ca) was similar in all plants despite the large variation in maximum stomatal conductance. Carboxylation efficiency was greater in plants from 780 m than in plants from 350 m. Altitude of origin has a strong influence on the photo-synthetic performance of N. cunninghamii plants even when grown under controlled conditions, and this influence is expressed in both leaf biochemistry (carboxylation efficiency) and leaf morphology (stomatal density).

scholarly journals Photosynthetic efficiency and production of cowpea cultivars under deficit irrigation

2018 ◽  
Vol 13 (5) ◽  
pp. 1 ◽  
Author(s):  
Alberto Soares de Melo ◽  
Allisson Rafael Ferreira da Silva ◽  
Alexson Filgueiras Dutra ◽  
Wellison Filgueiras Dutra ◽  
Marcos Eric Barbosa Brito ◽  
...  
Keyword(s):  
Water Deficit ◽  
Deficit Irrigation ◽  
Photosynthetic Efficiency ◽  
Arid Regions ◽  
Carbon Fixation ◽  
Management Strategies ◽  
Carbon Assimilation ◽  
Green Beans ◽  
Gas Exchanges ◽  
Cowpea Cultivars

Cowpea is a crop with great economic, social and food importance in semi-arid regions, but its production is drastically reduced by the water deficit in these regions, requiring better management strategies that allow the crop’s production. This study therefore aimed to evaluate the photosynthetic efficiency and production of cowpea cultivars under deficit irrigation replacement levels. The experiment tested three cowpea genotypes (G1 = ‘BRS Aracé’, G2 = ‘BR 17 Gurguéia’ and G3 = ‘BRS Marataoã’) and four irrigation depths (40, 60, 80 and 100% of ETc), resulting in a 3 x 4 factorial scheme, arranged in randomized complete blocks design with four replicates. During the experiment, the gas exchanges, chlorophyll a fluorescence and production of the cowpea genotypes under deficit irrigation were evaluated. Carbon fixation in the photosynthetic metabolism of cowpea plants was reduced by accentuated water deficit, regardless of the genotype. The low stress severity was indicated by the lack of effects on chlorophyll fluorescence, indicating that the reduction in the rate of carbon assimilation was due to the stomatal effects. The irrigation with 80% of ETc can be used in the cultivation of the respective cultivars, but with small losses in the production. Among the genotypes, ‘BRS Marataoã’ stands out with respect to yield, with higher values for weight of pods and green beans.

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