The boreal dwarf shrub Vaccinium vitis-idaea retains its capacity for photosynthesis through the winter

Botany ◽  
2008 ◽  
Vol 86 (5) ◽  
pp. 491-500 ◽  
Author(s):  
Robin Lundell ◽  
Timo Saarinen ◽  
Helena Åström ◽  
Heikki Hänninen
Keyword(s):  
Snow Cover ◽  
Photosynthetic Capacity ◽  
Soluble Sugars ◽  
Photosynthetic Apparatus ◽  
Leaf Tissue ◽  
Relative Effect ◽  
Effect Of Temperature ◽  
Winter Temperatures ◽  
Yearly Maximum ◽  
One Year

The ability to retain their photosynthetic capacity through the winter may be important for plants in boreal conditions, where the growing season is relatively short and winter temperatures fluctuate from severe freezing up to near 0 °C. The snow cover is an important protector for field-layer plants against both extreme freezing and excessive light, both of which could damage the photosynthetic apparatus. To understand the importance of wintertime photosynthetic activity for evergreen boreal dwarf shrubs, the photosynthesis of Vaccinium vitis-idaea L. was monitored in field conditions for one year. A dynamic model was used to determine the relative effect of temperature on the photosynthetic capacity. Our results show that V. vitis-idaea retains its photosynthetic capacity throughout the winter: its average photosynthetic capacity in winter was almost 25% of the yearly maximum measured. Changes in photosynthetic capacity over the year reflect the changes in air temperature with a certain delay, except in summer. Concentrations of soluble sugars remained high during the winter months, probably as a consequence of CO2 uptake under the snow cover. Our measurements indicated no significant damage to the leaf tissue over the winter, but suggest that photoinhibition may occur immediately after snowmelt.

scholarly journals 116 ANATOMICAL CHARACTERIZATION OF PHOTOSYNTHETIC CAPACITY OF EIGHT Fragaria chiloensis GENOTYPES

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 445a-445
Author(s):  
Paul W. Foote ◽  
J. Scott Cameron ◽  
Stephen F. Klauer
Keyword(s):  
Cross Sections ◽  
Photosynthetic Capacity ◽  
Stomatal Density ◽  
Genotypic Variation ◽  
Photosynthetic Apparatus ◽  
Leaf Tissue ◽  
Genotypic Differences ◽  
Cross Sectional ◽  
Palisade Cell ◽  
Anatomical Parameters

Leaf-area based CO2 assimilation rate (ALA as an Indicator of genotypic differences in photosynthetic capacity is questioned on the basis of correlations found between ALA and specific leaf weight and small leaf size. To address this question of photosynthetic apparatus concentration In F. chiloensis genotypes differing significantly in ALA, visual image analysis software was used to quantify a number of leaf anatomy parameters. In 1991 and 1992, after gas exchange measurements in the field, leaf tissue was prepared In cross-sections and leaf clearings for light microscopy. Cross-sections were used to measure internal anatomical parameters and clearings for vein and stomatal densities. Analysis of variance of 1991\92 measurements showed significant genotypic variation for leaf veination, leaf thickness, palisade cell length, cross-sectional area In mesophyll tissue and internal air space. Differences in stomatal density were observed in 1991. None of the anatomical parameters measured were correlated with ALA. This suggests that the concentration of physical apparatus Is not the major source of variation In ALA among these eight genotypes.

scholarly journals Spatio-Temporal Variation Characteristics of Snow Depth and Snow Cover Days over the Tibetan Plateau

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 307
Author(s):  
Chi Zhang ◽  
Naixia Mou ◽  
Jiqiang Niu ◽  
Lingxian Zhang ◽  
Feng Liu
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Snow Depth ◽  
Feedback Effect ◽  
Effect Of Temperature ◽  
The Tibetan Plateau ◽  
Reanalysis Dataset ◽  
Spatio Temporal ◽  
The Impact ◽  
Main Factor

Changes in snow cover over the Tibetan Plateau (TP) have a significant impact on agriculture, hydrology, and ecological environment of surrounding areas. This study investigates the spatio-temporal pattern of snow depth (SD) and snow cover days (SCD), as well as the impact of temperature and precipitation on snow cover over TP from 1979 to 2018 by using the ERA5 reanalysis dataset, and uses the Mann–Kendall test for significance. The results indicate that (1) the average annual SD and SCD in the southern and western edge areas of TP are relatively high, reaching 10 cm and 120 d or more, respectively. (2) In the past 40 years, SD (s = 0.04 cm decade−1, p = 0.81) and SCD (s = −2.3 d decade−1, p = 0.10) over TP did not change significantly. (3) The positive feedback effect of precipitation is the main factor affecting SD, while the negative feedback effect of temperature is the main factor affecting SCD. This study improves the understanding of snow cover change and is conducive to the further study of climate change on TP.

scholarly journals Influence of High Temperature on Photosynthesis, Antioxidative Capacity of Chloroplast, and Carbon Assimilation among Heat-tolerant and Heat-susceptible Genotypes of Nonheading Chinese Cabbage

HortScience ◽  
2017 ◽  
Vol 52 (11) ◽  
pp. 1464-1470 ◽  
Author(s):  
Lingyun Yuan ◽  
Yujie Yuan ◽  
Shan Liu ◽  
Jie Wang ◽  
Shidong Zhu ◽  
...  
Keyword(s):  
High Temperature ◽  
Chinese Cabbage ◽  
Photosynthetic Capacity ◽  
Photochemical Efficiency ◽  
Membrane Integrity ◽  
Photosynthetic Apparatus ◽  
Carbon Assimilation ◽  
Light Reaction ◽  
Chlorophyll Contents ◽  
Heat Tolerant

High temperature (HT) is a major environmental stress limiting oversummer production of nonheading Chinese cabbage (NHCC, Brassica campestris ssp. chinensis Makino). In the present study, the effects of HT on photosynthetic capacity, including light reaction and carbon assimilation, were completely investigated in two NHCC, ‘xd’ (heat-tolerant), and ‘sym’ (heat-susceptible). The two genotypes showed significant differences in plant morphology, photosynthetic capacity, and photosynthate metabolism (carboassimilation). HT caused a decrease in photosynthesis, chlorophyll contents, and photochemical activity in NHCC. However, these main photosynthetic-related parameters, including net photosynthetic rate (PN), maximal photochemical efficiency of PSII (Fv/Fm), and total chlorophyll content in ‘xd’, were significantly higher than those of ‘sym’ plants. The antioxidant contents and antioxidative enzyme activities of ascorbic acid-reduced glutathione cycle in the chloroplast of ‘xd’ were significantly higher than those of ‘sym’. Microscopic analyses revealed that HT affected the structure of photosynthetic apparatus and membrane integrity to a different extent, whereas ‘xd’ could maintain a better integrated chloroplast shape and thylakoid. Inhibited light reaction also hampered carbon assimilation, resulting in a decline of carboxylation efficiency and imbalance of carbohydrate metabolism. However, larger declined extents in these data were presented in ‘sym’ (heat-susceptible) than ‘xd’ (heat-tolerant). The heat-tolerant genotype ‘xd’ had a better capacity for self-protection by improved light reaction and carbon assimilation responding to HT stress.

scholarly journals Environmental effects on photosynthetic capacity of bean genotypes

2004 ◽  
Vol 39 (7) ◽  
pp. 615-623 ◽  
Author(s):  
Rafael Vasconcelos Ribeiro ◽  
Mauro Guida dos Santos ◽  
Gustavo Maia Souza ◽  
Eduardo Caruso Machado ◽  
Ricardo Ferraz de Oliveira ◽  
...  
Keyword(s):  
High Temperature ◽  
Natural Condition ◽  
Temperature Effects ◽  
Environmental Changes ◽  
Photosynthetic Capacity ◽  
Photosynthetic Apparatus ◽  
Co2 Assimilation ◽  
Fluorescence Yield ◽  
Environmental Condition ◽  
Response Curves

Photosynthetic responses to daily environmental changes were studied in bean (Phaseolus vulgaris L.) genotypes 'Carioca', 'Ouro Negro', and Guarumbé. Light response curves of CO2 assimilation and stomatal conductance (g s) were also evaluated under controlled (optimum) environmental condition. Under this condition, CO2 assimilation of 'Carioca' was not saturated at 2,000 µmol m-2 s-1, whereas Guarumbé and 'Ouro Negro' exhibited different levels of light saturation. All genotypes showed dynamic photoinhibition and reversible increase in the minimum chlorophyll fluorescence yield under natural condition, as well as lower photosynthetic capacity when compared with optimum environmental condition. Since differences in g s were not observed between natural and controlled conditions for Guarumbé and 'Ouro Negro', the lower photosynthetic capacity of these genotypes under natural condition seems to be caused by high temperature effects on biochemical reactions, as suggested by increased alternative electron sinks. The highest g s values of 'Carioca' were observed at controlled condition, providing evidences that reduction of photosynthetic capacity at natural condition was due to low g s in addition to the high temperature effects on the photosynthetic apparatus. 'Carioca' exhibited the highest photosynthetic rates under optimum environmental condition, and was more affected by daily changes of air temperature and leaf-to-air vapor pressure difference.

scholarly journals Cold induced changes on sugar contents and respiratory enzyme activities in coffee genotypes

2010 ◽  
Vol 40 (4) ◽  
pp. 781-786 ◽  
Author(s):  
Fábio Luiz Partelli ◽  
Henrique Duarte Vieira ◽  
Ana Paula Dias Rodrigues ◽  
Isabel Pais ◽  
Eliemar Campostrini ◽  
...  
Keyword(s):  
Soluble Sugar ◽  
Recovery Period ◽  
Soluble Sugars ◽  
Coffea Canephora ◽  
Correct Selection ◽  
Respiratory Enzymes ◽  
Period 2 ◽  
Acclimation Period ◽  
Cold Sensitive ◽  
One Year

The present research aimed to characterize some biochemical responses of Coffea canephora (clones 02 and 153) and C. arabica (Catucaí IPR 102) genotypes subjected to low positive temperatures, helping to elucidate the mechanisms involved in cold tolerance. For that, one year old plants were subjected successively to 1) a temperature decrease (0.5°C a day) from 25/20°C to 13/8°C (acclimation period), 2) a three day chilling cycle (3x13/4°C) and to 3) a recovery period of 14 days (25/20°C). In Catucaí (less cold sensitive when compared to clone 02) there was an increased activity in the respiratory enzymes malate dehydrogenase and pyruvate kinase. Furthermore, Catucaí showed significant increases along the cold imposition and the higher absolute values after chilling exposure of the soluble sugars (sucrose, glucose, fructose, raffinose, arabinose and mannitol) that are frequently involved in osmoregulation and membrane stabilization/protection. The analysis of respiratory enzymes and of soluble sugar balance may give valuable information about the cold acclimation/tolerance mechanisms, contributing to a correct selection and breeding of Coffea sp. genotypes.

scholarly journals Submesoscale Dynamics in the Northern Gulf of Mexico. Part II: Temperature–Salinity Relations and Cross-Shelf Transport Processes

2017 ◽  
Vol 47 (9) ◽  
pp. 2347-2360 ◽  
Author(s):  
Roy Barkan ◽  
James C. McWilliams ◽  
M. Jeroen Molemaker ◽  
Jun Choi ◽  
Kaushik Srinivasan ◽  
...  
Keyword(s):  
Potential Energy ◽  
Gulf Of Mexico ◽  
Horizontal Resolution ◽  
Relative Effect ◽  
Distribution Functions ◽  
Transport Processes ◽  
Effect Of Temperature ◽  
Loop Current ◽  
Northern Gulf Of Mexico ◽  
Available Potential Energy

AbstractThis paper, the second of three, investigates submesoscale dynamics in the northern Gulf of Mexico under the influence of the Mississippi–Atchafalaya River system, using numerical simulations at 500-m horizontal resolution with climatological atmospheric forcing. The Turner angle Tu, a measure of the relative effect of temperature and salinity on density, is examined with respect to submesoscale current generation in runs with and without riverine forcing. Surface Tu probability density functions in solutions including rivers show a temperature-dominated signal offshore, associated with Loop Current water, and a nearshore salinity-dominated signal, associated with fresh river water, without a clear compensating signal, as often found instead in the ocean’s mixed layer. The corresponding probability distribution functions in the absence of rivers differ, illustrating the key role played by the freshwater output in determining temperature–salinity distributions in the northern Gulf of Mexico during both winter and summer. A quantity referred to as temperature–salinity covariance is proposed to determine what fraction of the available potential energy that is released during the generation of submesoscale circulations leads to the destruction of density gradients while leaving spice gradients untouched, thereby leading to compensation. It is shown that the fresh river fronts to the east of the Bird’s Foot can evolve toward compensation in concert with a gradual release of available potential energy. It is further demonstrated that, during winter, the cross-shelf freshwater transport mechanism to the west of the Bird’s Foot is well approximated by a diffusive process, whereas to the east is better represented by a ballistic process associated with the Mississippi water that converges in a jetlike pattern.

scholarly journals Short-term Effects of Fumigation with Gaseous Methanol on Photosynthesis in Horticultural Plants

1999 ◽  
Vol 124 (4) ◽  
pp. 377-380 ◽  
Author(s):  
Francesco Loreto ◽  
Domenico Tricoli ◽  
Mauro Centritto ◽  
Arturo Alvino ◽  
Sebastiano Delfine
Keyword(s):  
Cucumis Melo ◽  
Time Course ◽  
Prunus Avium ◽  
Photosynthetic Capacity ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Sensitive Species ◽  
Short Term ◽  
Methanol Vapor ◽  
Temporary Inhibition

Short-term fumigation with 1% methanol in air was carried out to investigate effects on the photosynthetic apparatus of horticultural species characterized by leaves with different stomatal distribution. Methanol decreased the photosynthetic capacity of all species. The hypostomatous cherry (Prunus avium L.) was the most sensitive species. Between the two amphistomatous species, the effect was smaller in pepper (Capsicum annuum L. var. annuum) than in melon (Cucumis melo L.). A 4-minute fumigation caused a stronger inhibition of photosynthesis than a 90-second fumigation. The time course of the inhibition of the photosynthetic electron transport following a methanol fumigation of cherry leaves suggests that methanol starts inhibiting photosynthesis and photorespiration after ≈60 seconds and that the effect is complete after 180 seconds. This inhibition is not permanent, however, since gas-exchange properties recovered within 24 hours. Methanol vapor effects were greatest when leaves were fumigated on the surfaces with stomata. However, fumigation with methanol does not affect stomatal conductance. Therefore, inhibition of photosynthesis following methanol fumigation can be attributed to a temporary inhibition of biochemical reactions.

scholarly journals The Crosstalk of Melatonin and Hydrogen Sulfide Determines Photosynthetic Performance by Regulation of Carbohydrate Metabolism in Wheat under Heat Stress

Plants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1778 ◽  
Author(s):  
Noushina Iqbal ◽  
Mehar Fatma ◽  
Harsha Gautam ◽  
Shahid Umar ◽  
Adriano Sofo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Sulfide ◽  
Heat Stress ◽  
Carbohydrate Metabolism ◽  
Soluble Sugars ◽  
Photosynthetic Apparatus ◽  
Time Duration ◽  
H2o2 Content ◽  
Metabolism Enzymes ◽  
Regulation Of Carbohydrate Metabolism

Photosynthesis is a pivotal process that determines the synthesis of carbohydrates required for sustaining growth under normal or stress situation. Stress exposure reduces the photosynthetic potential owing to the excess synthesis of reactive oxygen species that disturb the proper functioning of photosynthetic apparatus. This decreased photosynthesis is associated with disturbances in carbohydrate metabolism resulting in reduced growth under stress. We evaluated the importance of melatonin in reducing heat stress-induced severity in wheat (Triticum aestivum L.) plants. The plants were subjected to 25 °C (optimum temperature) or 40 °C (heat stress) for 15 days at 6 h time duration and then developed the plants for 30 days. Heat stress led to oxidative stress with increased production of thiobarbituric acid reactive substances (TBARS) and hydrogen peroxide (H2O2) content and reduced accrual of total soluble sugars, starch and carbohydrate metabolism enzymes which were reflected in reduced photosynthesis. Application of melatonin not only reduced oxidative stress through lowering TBARS and H2O2 content, augmenting the activity of antioxidative enzymes but also increased the photosynthesis in plant and carbohydrate metabolism that was needed to provide energy and carbon skeleton to the developing plant under stress. However, the increase in these parameters with melatonin was mediated via hydrogen sulfide (H2S), as the inhibition of H2S by hypotaurine (HT; H2S scavenger) reversed the ameliorative effect of melatonin. This suggests a crosstalk of melatonin and H2S in protecting heat stress-induced photosynthetic inhibition via regulation of carbohydrate metabolism.

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