scholarly journals Heat Tolerance of Five Taxa of Birch (Betula): Physiological Responses to Supraoptimal Leaf Temperatures

1994 ◽  
Vol 119 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Thomas G. Ranney ◽  
Mary M. Peet
Keyword(s):  
Gas Exchange ◽  
High Temperatures ◽  
Heat Tolerance ◽  
Leaf Gas Exchange ◽  
Photochemical Efficiency ◽  
Calvin Cycle ◽  
Differential Sensitivity ◽  
Ps Ii ◽  
Fluorescence Measurements ◽  
Paper Birch

Leaf gas-exchange and chlorophyll fluorescence measurements were used as indexes for evaluating heat tolerance among five taxa of birch: paper (Betula papyrifera Marsh.), European (B. pendula Roth.), Japanese (B. platyphylla var. japonica Hara. cv. Whitespire), Himalayan (B. jacquemontii Spach.), and river (B. nigra L. cv. Heritage). Gas-exchange measurements were conducted on individual leaves at temperatures ranging from 25 to 40C. River birch maintained the highest net photosynthetic rates (Pn) at high temperatures, while Pn of paper birch was reduced the most. Further study of river and paper birch indicated that the reduced Pn at high temperatures and the differential sensitivity between taxa resulted from several factors. Inhibition of Pn at higher temperatures was due largely to nonstomatal limitations for both taxa. Increases in respiration rates, decreases in maximal photochemical efficiency of photosystem (PS) II (FV/FM), and possible reductions in light energy directed to PS II (F0 quenching) were apparent for both taxa. The capacity of river birch to maintain greater Pn at higher temperatures seemed to result from a lower Q10 for dark respiration and possibly greater thermotolerance of the Calvin cycle as indicated by a lack of nonphotochemical fluorescence quenching with increasing temperatures. Thermal injury, as indicated by a rapid increase in minimal, dark-acclimated (F0) fluorescence, was not evident for either paper or river birch until temperatures reached ≈49C and was similar for both taxa.

Effects of heat stress on gas exchange and photosystem II (PSII) photochemical activity of Phillyrea angustifolia exposed to elevated CO2 and subsaturating irradiance

Botany ◽  
2008 ◽  
Vol 86 (4) ◽  
pp. 435-441 ◽  
Author(s):  
Luca Vitale ◽  
Carmen Arena ◽  
Amalia Virzo De Santo ◽  
Nicola D’Ambrosio
Keyword(s):  
Heat Stress ◽  
Electron Transport ◽  
Gas Exchange ◽  
Photosystem Ii ◽  
Photochemical Efficiency ◽  
Calvin Cycle ◽  
Fluorescence Measurements ◽  
Significant Difference ◽  
Psii Photochemical Efficiency ◽  
Phillyrea Angustifolia

Gas exchange and chlorophyll a fluorescence measurements were performed simultaneously on leaves of Phillyrea angustifolia L. to assess the effects of heat stress (30 min at 40 °C) on photosynthesis and photosystem II (PSII) photochemical efficiency of plants grown at ambient CO2 and exposed to an elevated CO2 concentration (800 µmol·mol–1) and 300 µmol photons·m–2·s–1. No significant difference was found in the heat-induced decreases of net photosynthesis (PN), quantum yield of PSII electron transport (ΦPSII), and maximum PSII photochemical efficiency (Fv/Fm) between plants exposed to ambient and elevated CO2 concentrations, showing that elevated CO2 was not able to reduce the potential for photoinhibition at high temperatures under moderate light conditions. The heat-induced decrease of PN was higher than that of ΦPSII indicating that reductive power was more utilized in non-assimilatory processes than in CO2 fixation at both CO2 treatments. This result suggested that impairment of the Calvin cycle rather than electron transport inhibition was the main cause of the limitation in CO2 fixation.

scholarly journals COMPARATIVE HEAT TOLERANCE AMONG FIVE SPECIES OF BIRCH

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 627d-627
Author(s):  
Thomas G. Ranney
Keyword(s):  
Chlorophyll Fluorescence ◽  
Stomatal Conductance ◽  
Heat Tolerance ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
Betula Papyrifera ◽  
Respiration Rates ◽  
Fluorescence Measurements ◽  
Variable Chlorophyll Fluorescence ◽  
Paper Birch

Leaf gas exchange and chlorophyll fluorescence measurements were used as indices for evaluating heat tolerance among five species of birch: paper (Betula papyrifera), European (B. pendula), Japanese (B. platyphylla var. japonica `Whitespire'), Himalayan (B. jacquemontii), and river (B. nigra). Measurements were conducted on individual leaves at temperatures ranging from 25C to 40C. Carbon exchange rates (CER) were depressed for all species at 40C. However, there was considerable variation in both absolute and relative (percent of maximum) CER among species at 40C; river birch maintained the highest absolute and relative CER while CER of paper birch was reduced the most. Although stomatal conductance of paper birch decreased at higher temperatures, internal leaf CO2 increased indicating that reduced stomatal conductance was not responsible for decreased CER. Stomatal conductance of river birch increased at higher temperatures which provided for enhanced uptake of CO2 and greater evaporative cooling. Variable chlorophyll fluorescence decreased similarly for both species with increasing temperatures. Measurements of dark respiration rates over the range of 25C to 40C suggested that the primary factor influencing variation in CER at higher temperatures was due to variation in respiration rates at higher temperatures.

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.

scholarly journals Leaf Gas Exchange and Chlorophyll a Fluorescence Imaging of Rice Leaves Infected with Monographella albescens

2015 ◽  
Vol 105 (2) ◽  
pp. 180-188 ◽  
Author(s):  
Sandro Dan Tatagiba ◽  
Fábio Murilo DaMatta ◽  
Fabrício Ávila Rodrigues
Keyword(s):  
Gas Exchange ◽  
Fluorescence Imaging ◽  
Leaf Gas Exchange ◽  
Photosynthetic Pigment ◽  
Photochemical Efficiency ◽  
Photosynthetic Apparatus ◽  
Photochemical Quenching ◽  
Chl A ◽  
Chl A Fluorescence ◽  
Rice Leaves

This study was intended to analyze the photosynthetic performance of rice leaf blades infected with Monographella albescens by combining chlorophyll (Chl) a fluorescence images with gas exchange and photosynthetic pigment pools. The net CO2 assimilation rate, stomatal conductance, transpiration rate, total Chl and carotenoid pools, and Chl a/b ratio all decreased but the internal CO2 concentration increased in the inoculated plants compared with their noninoculated counterparts. The first detectable changes in the images of Chl a fluorescence from the leaves of inoculated plants were already evident at 24 h after inoculation (hai) and increased dramatically as the leaf scald lesions expanded. However, these changes were negligible for the photosystem II photochemical efficiency (Fv/Fm) at 24 hai, in contrast to other Chl fluorescence traits such as the photochemical quenching coefficient, yield of photochemistry, and yield for dissipation by downregulation; which, therefore, were much more sensitive than the Fv/Fm ratio in assessing the early stages of fungal infection. It was also demonstrated that M. albescens was able to impair the photosynthetic process in both symptomatic and asymptomatic leaf areas. Overall, it was proven that Chl a fluorescence imaging is an excellent tool to describe the loss of functionality of the photosynthetic apparatus occurring in rice leaves upon infection by M. albescens.

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.

DROUGHT TOLERANCE IN MULBERRY (MORUS SPP.): A PHYSIOLOGICAL APPROACH WITH INSIGHTS INTO GROWTH DYNAMICS AND LEAF YIELD PRODUCTION

2010 ◽  
Vol 46 (4) ◽  
pp. 471-488 ◽  
Author(s):  
ANIRBAN GUHA ◽  
GIRISH KUMAR RASINENI ◽  
ATTIPALLI RAMACHANDRA REDDY
Keyword(s):  
Gas Exchange ◽  
Photosystem Ii ◽  
Drought Tolerance ◽  
Leaf Gas Exchange ◽  
Growth Dynamics ◽  
Growing Season ◽  
Physiological Variables ◽  
Fluorescence Measurements ◽  
Yield Production ◽  
Leaf Yield

SUMMARYThe present study documents critical analysis of drought-induced physiological responses in mulberry (Morus spp.) with insights into growth dynamics and leaf productivity. The study was performed for two years in a two-phase experimental design combining both field (experiment no. 1) and glasshouse (experiment no. 2) observations. In field assays, we surveyed 15 mulberry genotypes under two irrigation regimes: well-watered (20 to 24 irrigations in each growing season) and water-limited (irrigated once in a fortnight in each growing season). The genotypes were assessed for variation in key leaf gas exchange characteristics: net photosynthetic rates (Pn), stomatal conductance of CO2 (gs), transpiration rates (E) and instantaneous water use efficiency (WUEi). Leaf yield/plant was considered to determine the tolerance index (TI). Drought stress severely down-regulated leaf-level physiological variables in the susceptible genotypes resulting in poor leaf yield. However, genotypes S-13 and V-1 performed better in terms of leaf gas exchange and proved their superiority over other genotypes in drought tolerance. Conversely, genotypes DD and Bogurai were highly susceptible to drought. Under glasshouse conditions, the combined leaf gas exchange/chlorophyll a fluorescence measurements further dissected out stomatal and non-stomatal restrictions to Pn. As internal/ambient CO2 ratio (Ci/Ca) decreased concurrently with gs in non-irrigated stands, it appeared that greater stomatal limitation to Pn was associated with decreased photo-assimilation and leaf yield production. Further, higher leaf temperature (TL) (>35 °C) and down-regulation of maximum quantum yield of photosystem II (Fv/Fm) were apparent in the susceptible compared to the tolerant genotypes, which indicated chronic photoinhibition due to photo-inactivation of photosystem II centres in the susceptible genotypes. Drought-induced trade-offs in biomass allocation were also highlighted. Overall, our results suggest that greater rooting vigour and leaf hydration status, minimal stomatal inhibition and stabilized photochemistry might play major roles in maintaining higher Pn and associated gas exchange functions in drought-tolerant mulberry genotypes under water stress conditions. The higher leaf yield production in tolerant than susceptible genotypes can be attributed to minimal plasticity in foliar gas exchange traits and better quantitative growth characteristics under low water regimes.

Limited physiological acclimation to recurrent heatwaves in two boreal tree species

2020 ◽  
Vol 40 (12) ◽  
pp. 1680-1696
Author(s):  
Maegan A Gagne ◽  
Duncan D Smith ◽  
Katherine A McCulloh
Keyword(s):  
Gas Exchange ◽  
Tree Mortality ◽  
Leaf Gas Exchange ◽  
White Spruce ◽  
Extreme Heat ◽  
Photosynthetic Acclimation ◽  
Lower Latitude ◽  
Minor Effect ◽  
Water Restriction ◽  
Paper Birch

Abstract The intensity of extreme heat and drought events has drastically risen in recent decades and will likely continue throughout the century. Northern forests have already seen increases in tree mortality and a lack of new recruitment, which is partially attributed to these extreme events. Boreal species, such as paper birch (Betula papyrifera) and white spruce (Picea glauca), appear to be more sensitive to these changes than lower-latitude species. Our objectives were to investigate the effects of repeated heatwaves and drought on young paper birch and white spruce trees by examining (i) responses in leaf gas exchange and plant growth and (ii) thermal acclimation of photosynthetic and respiratory traits to compare ecophysiological responses of two co-occurring, yet functionally dissimilar species. To address these objectives, we subjected greenhouse-grown seedlings to two consecutive summers of three 8-day long, +10 °C heatwaves in elevated atmospheric CO2 conditions with and without water restriction. The data show that heatwave stress reduced net photosynthesis, stomatal conductance and growth—more severely so when combined with drought. Acclimation of both photosynthesis and respiration did not occur in either species. The combination of heat and drought stress had a similar total effect on both species, but each species adjusted traits differently to the combined stress. Birch experienced greater declines in gas exchange across both years and showed moderate respiratory but not photosynthetic acclimation to heatwaves. In spruce, heatwave stress reduced the increase in basal area in both experimental years and had a minor effect on photosynthetic acclimation. The data suggest these species lack the ability to physiologically adjust to extreme heat events, which may limit their future distributions, thereby altering the composition of boreal forests.

scholarly journals Leaf Gas Exchange Performance of Ten Quinoa Genotypes under a Simulated Heat Wave

Plants ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 81 ◽  
Author(s):  
Ashley Eustis ◽  
Kevin M. Murphy ◽  
Felipe H. Barrios-Masias
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Gas Exchange ◽  
High Temperatures ◽  
Heat Waves ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
Reproductive Capacity ◽  
Plant Water ◽  
Assimilation Capacity

Quinoa (Chenopodium quinoa Willd.) is a highly nutritious crop that is resilient to a wide range of abiotic stresses; however, sensitivity to high temperatures is regarded as an impediment to adoption in regions prone to heat waves. Heat stress is usually associated with a decrease in crop reproductive capacity (e.g., pollen viability), yet little is known about how leaf physiological performance of quinoa is affected by high temperatures. Several trials were conducted to understand the effect of high temperatures, without confounding stressors such as drought, on ten selected quinoa genotypes considered to encompass heat sensitive and heat tolerant plant material. Plants were grown under favorable temperatures and exposed to two temperature treatments over four consecutive days. The heat treatment simulated heat waves with maximum and minimum temperatures higher during the day and night, while the control treatment was maintained under favorable temperatures (maximum and minimum temperatures for ‘Heat’: 45/30 °C and ‘Control’: 20/14 °C). Leaf gas exchange (day), chlorophyll fluorescence (predawn and day) and dark respiration (night) were measured. Results show that most quinoa genotypes under the heat treatment increased their photosynthetic rates and stomatal conductance, resulting in a lower intrinsic water use efficiency. This was partly corroborated by an increase in the maximum quantum yield of photosystem II (Fv/Fm). Dark respiration decreased under the heat treatment in most genotypes, and temperature treatment did not affect aboveground biomass by harvest (shoot and seeds). These results suggest that heat stress alone favors increases in leaf carbon assimilation capacity although the tradeoff is higher plant water demand, which may lead to plant water stress and lower yields under non-irrigated field conditions.

scholarly journals Growth, Gas Exchange, and Chlorophyll Fluorescence of Four Ornamental Herbaceous Perennials during Water Deficit Conditions

2006 ◽  
Vol 131 (4) ◽  
pp. 469-475 ◽  
Author(s):  
Terri Starman ◽  
Leonardo Lombardini
Keyword(s):  
Chlorophyll Fluorescence ◽  
Gas Exchange ◽  
Water Use ◽  
Leaf Gas Exchange ◽  
Photochemical Efficiency ◽  
Dry Weight ◽  
Drought Treatment ◽  
Greenhouse Production ◽  
Herbaceous Perennials ◽  
Leaf Level

A study was conducted to characterize the morphological and physiological responses of four herbaceous perennial species subjected to two subsequent drought cycles. Lantana camara L. `New Gold' (lantana), Lobelia cardinalis L. (cardinal flower), Salvia farinacea Benth. `Henry Duelberg' (mealy sage), and Scaevola aemula R. Br. `New Wonder' (fan flower) were subjected to two consecutive 10-day drought cycles. Growth response, leaf gas exchange, and chlorophyll fluorescence were measured during the experiment. The morphology of L. cardinalis and L. camara was not affected by drought, while S. farinacea had reductions in plant height and leaf area and S. aemula had reductions in dry weight. Overall, plant growth and development continued even when substrate water content was reduced to 0.13 mm3·mm-3, which indicated a level of substrate water below container capacity was sufficient for greenhouse production of these species. The drought treatments had little effect on the photochemical efficiency (Fv/Fm) of Photosystem II. An increase in minimal fluorescence (Fo) was observed in S. aemula on the last day of the second cycle. Drought treatment caused increased leaf-level water use efficiency (WUE) at the end of the first cycle in L. cardinalis and S. aemula, but not in L. camara and S. farinacea. Plants of L. camara, S. farinacea, and S. aemula that had received drought during both cycles became more water use efficient by the end of the second cycle, but L. cardinalis did not.

scholarly journals Salt stress induced damages on the photosynthesis of physic nut young plants

2011 ◽  
Vol 68 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Evandro Nascimento da Silva ◽  
Rafael Vasconcelos Ribeiro ◽  
Sérgio Luiz Ferreira-Silva ◽  
Ricardo Almeida Viégas ◽  
Joaquim Albenisio Gomes Silveira
Keyword(s):  
Salt Stress ◽  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Photochemical Efficiency ◽  
Crop Productivity ◽  
Photosynthetic Performance ◽  
Limiting Factor ◽  
Physic Nut ◽  
Gas Exchange Parameters ◽  
Randomized Design

Salinity is a major limiting factor to crop productivity in the world especially in semiarid regions. The aim of this study was to evaluate the photosynthetic resistance of Jatropha curcas (L.) young plants subjected to salt stress. The experiment was carried out in a completely randomized design with treatments in a 2 x 3 factorial: two NaCl levels (0 and 100 mmol L-1) and three harvest times: 7 and 14 days of salt exposure and three days of recovery. Leaf Na+ and Cl-concentrations and the K+/Na+ ratios, after seven days of salt exposure, did not reach ionic toxic levels, suggesting that the NaCl-induced osmotic effects prevailed over the ionic ones. Under this condition, the salt stress caused reduction in leaf gas exchange parameters, such as CO2 fixation, stomatal conductance and transpiration. In contrast, salt stress did not change the photochemical efficiency of photossystem II. Conversely, after 14 days of treatment, Na+ and Clions reached very high concentrations, up to toxic levels in leaves. Under such conditions, both leaf gas exchange and photochemistry suffered strong impairment probably caused by ionic toxicity. The recovery treatment for 3d did not significantly decrease the leaf salt concentrations and no improvement was observed in the photosynthetic performance. Physic nut young plants are sensitive to high NaCl-salinity conditions, with high leaf Na+ and Cl- concentrations, low K+/Na+ ratio and great photosynthetic damages due to stomatal and biochemical limitations.

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