scholarly journals Responses of Aspen Leaves to Heatflecks: Both Damaging and Non-Damaging Rapid Temperature Excursions Reduce Photosynthesis

Plants ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 145 ◽  
Author(s):  
Katja Hüve ◽  
Irina Bichele ◽  
Hedi Kaldmäe ◽  
Bahtijor Rasulov ◽  
Fernando Valladares ◽  
...  
Keyword(s):  
Light Intensity ◽  
Stomatal Closure ◽  
Heat Pulse ◽  
Leaf Temperature ◽  
Cellular Damage ◽  
Carbon Gain ◽  
Hybrid Aspen ◽  
Membrane Conductivity ◽  
European Aspen ◽  
Heat Pulses

During exposure to direct sunlight, leaf temperature increases rapidly and can reach values well above air temperature in temperate forest understories, especially when transpiration is limited due to drought stress, but the physiological effects of such high-temperature events are imperfectly understood. To gain insight into leaf temperature changes in the field and the effects of temperature variation on plant photosynthetic processes, we studied leaf temperature dynamics under field conditions in European aspen (Populus tremula L.) and under nursery conditions in hybrid aspen (P. tremula × P. tremuloides Michaux), and further investigated the heat response of photosynthetic activity in hybrid aspen leaves under laboratory conditions. To simulate the complex fluctuating temperature environment in the field, intact, attached leaves were subjected to short temperature increases (“heat pulses”) of varying duration over the temperature range of 30 °C–53 °C either under constant light intensity or by simultaneously raising the light intensity from 600 μmol m−2 s−1 to 1000 μmol m−2 s−1 during the heat pulse. On a warm summer day, leaf temperatures of up to 44 °C were measured in aspen leaves growing in the hemiboreal climate of Estonia. Laboratory experiments demonstrated that a moderate heat pulse of 2 min and up to 44 °C resulted in a reversible decrease of photosynthesis. The decrease in photosynthesis resulted from a combination of suppression of photosynthesis directly caused by the heat pulse and a further decrease, for a time period of 10–40 min after the heat pulse, caused by subsequent transient stomatal closure and delayed recovery of photosystem II (PSII) quantum yield. Longer and hotter heat pulses resulted in sustained inhibition of photosynthesis, primarily due to reduced PSII activity. However, cellular damage as indicated by increased membrane conductivity was not found below 50 °C. These data demonstrate that aspen is remarkably resistant to short-term heat pulses that are frequent under strongly fluctuating light regimes. Although the heat pulses did not result in cellular damage, heatflecks can significantly reduce the whole plant carbon gain in the field due to the delayed photosynthetic recovery after the heat pulse.

CAM ‐physiology and carbon gain of the orchid Phalaenopsis in response to light intensity, light integral and CO 2

2020 ◽  
Author(s):  
Sander W. Hogewoning ◽  
Stefan A.J. Boogaart ◽  
Evelien Tongerlo ◽  
Govert Trouwborst
Keyword(s):  
Light Intensity ◽  
Carbon Gain ◽  
Light Integral

scholarly journals Growth and carbon assimilation limitations in Ricinus communis (Euphorbiaceae) under soil water stress conditions

2010 ◽  
Vol 24 (3) ◽  
pp. 648-654 ◽  
Author(s):  
Tanise Luisa Sausen ◽  
Luís Mauro Gonçalves Rosa
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Drought Resistance ◽  
Ricinus Communis ◽  
Stomatal Closure ◽  
Carbon Assimilation ◽  
Stress Conditions ◽  
Carbon Gain ◽  
Resistant Species ◽  
Ricinus Communis L

Water availability may influence plant carbon gain and growth, with large impacts on plant yield. Ricinus communis (L.), a drought resistant species, is a crop with increasing economic importance in Brazil, due to its use in chemical industry and for the production of biofuels. Some of the mechanisms involved in this drought resistance were analyzed in this study by imposing progressive water stress to pot-grown plants under glasshouse conditions. Water withholding for 53 days decreased soil water gravimetric content and the leaf water potential. Plant growth was negatively and significantly reduced by increasing soil water deficits. With irrigation suspension, carbon assimilation and transpiration were reduced and remained mostly constant throughout the day. Analysis of A/Ci curves showed increased stomatal limitation, indicating that limitation imposed by stomatal closure is the main factor responsible for photosynthesis reduction. Carboxylation efficiency and electron transport rate were not affected by water stress up to 15 days after withholding water. Drought resistance of castor bean seems to be related to a pronounced, early growth response, an efficient stomatal control and the capacity to keep high net CO2 fixation rates under water stress conditions.

scholarly journals Heat-pulse propagation along nonequilibrium nanowires in thermomass theory

2016 ◽  
Vol 7 (2) ◽  
pp. 39-55
Author(s):  
Antonio Sellitto ◽  
Patrizia Rogolino ◽  
Isabella Carlomagno
Keyword(s):  
Temperature Gradient ◽  
Transport Equation ◽  
Heat Transport ◽  
Pulse Propagation ◽  
Heat Pulse ◽  
Average Temperature ◽  
Temperature Ranges ◽  
Heat Transport Equation ◽  
Heat Pulses ◽  
Theoretical Proposal

AbstractWe analyze the consequences of the nonlinear terms in the heat-transport equation of the thermomass theory on heat pulses propagating in a nanowire in nonequilibrium situations. As a consequence of the temperature dependence of the speeds of propagation, in temperature ranges wherein the specific heat shows negligible variations, heat pulses will shrink (or extend) spatially, and will increase (or decrease) their average temperature when propagating along a temperature gradient. A comparison with the results predicted by a different theoretical proposal on the shape of a propagating heat pulse is made, too.

Response of Plant Tissues to Nitrofen

Weed Science ◽  
1971 ◽  
Vol 19 (6) ◽  
pp. 662-666 ◽  
Author(s):  
J. Francisco Pereira ◽  
Walter E. Splittstoesser ◽  
Herbert J. Hopen
Keyword(s):  
Electron Transport ◽  
Oxygen Uptake ◽  
Thermal Injury ◽  
Spinacia Oleracea ◽  
Stomatal Closure ◽  
Leaf Temperature ◽  
High Light ◽  
Plant Tissues ◽  
Cyclic Photophosphorylation ◽  
Germination And Growth

Nitrofen (2,4-dichlorophenylp-nitrophenyl ether) injured meristematic tissues and reduced germination and growth of cabbage (Brassica oleraceavar.capitataL.) in the dark. Cabbage was more susceptible to nitrofen when the plants were grown under a low water potential or when they were maintained in the dark after spraying. This toxicity was overcome by exogenous sucrose and light was not required for nitrofen activity. Nitrofen promoted membrane permeability of red beet (Beta vulgarisL.) root sections and this was enhanced by dimethylsulfoxide (DMSO). Sucrose or Carbowax 1500 prevented this increase in permeability. Nitrofen inhibited non-cyclic photophosphorylation and electron transport in isolated spinach (Spinacia oleraceaL.) chloroplasts and increased oxygen uptake of cabbage leaf sections. These effects appeared dependent upon permeability. Nitrofen induced stomatal closure, decreased transpiration, and increased leaf temperature. The leaf sustains thermal injury under high temperatures or high light intensities.

Simultaneous Effects of Foliar Nitrogen, Temperature, and Humidity on Gas Exchange in Pinus radiata

1995 ◽  
Vol 22 (4) ◽  
pp. 615 ◽  
Author(s):  
DW Sheriff ◽  
JP Mattay
Keyword(s):  
Gas Exchange ◽  
Pinus Radiata ◽  
Vapour Pressure ◽  
Measurement Data ◽  
Carbon Assimilation ◽  
Vapour Pressure Deficit ◽  
Leaf Temperature ◽  
Carbon Gain ◽  
Foliar Nitrogen ◽  
Foliar N

Seedlings of Pinus radiata were grown in a glasshouse in large pots with sand as the potting mix. They were kept well-watered and frequently supplied with nutrient solutions which contained different amounts of nitrogen for different treatments. Carbon assimilation and diffusive conductance of the foliage were measured under steady-state conditions at saturating light in all treatments. Experimental variables were leaf-air vapour pressure difference and leaf temperature at time of measurement. Data were fitted to a non-linear regression equation to examine responses of carbon assimilation, diffusive conductance, transpiration, assimilatory nitrogen-use efficiency, and assimilatory transpiration efficiency to foliar nitrogen concentration expressed on a leaf area basis ([N]), to leaf temperature, and to leaf-air vapour pressure (D). Parameters from the regression have been used to plot three-dimensional surfaces, so that simultaneous effects of experimental variables can be easily visualised. Carbon assimilation increased linearly with foliar [N], declined exponentially as D increased, and had a broad temperature optimum between c. 14 and 38�C. Diffusive conductance increased linearly with foliar [N], was related to the reciprocal of D, and declined as temperature increased. Using climatic vapour pressure deficit and air temperature data for Canberra, ACT, and for Mount Gambier, SA, and with the functions that had been fitted to experimental data, it was found that these regional climatic differences have potential for appreciably affecting carbon gain and water loss in the regions, which have P. radiata plantations. Predicted differences in carbon gain are of the order of reported differences in stem growth in the regions. This shows the need to take into account regional variation in climatic variables that strongly affect gas exchange when investigating regional differences in productivity.

Does increased air humidity affect stomatal morphology and functioning in hybrid aspen?

Botany ◽  
2015 ◽  
Vol 93 (4) ◽  
pp. 243-250 ◽  
Author(s):  
Aigar Niglas ◽  
Meeli Alber ◽  
Kristi Suur ◽  
Anna K. Jasińska ◽  
Priit Kupper ◽  
...  
Keyword(s):  
Vapour Pressure ◽  
Stomatal Density ◽  
Vapour Pressure Deficit ◽  
Carbon Gain ◽  
Hybrid Aspen ◽  
Air Humidity ◽  
Response Curves ◽  
Opposite Pattern ◽  
Stomatal Morphology ◽  
Stomatal Sensitivity

The study investigated the effects of exposure to increased relative air humidity (RH) on stomatal morphology and sensitivity to stomata closure inducing stimulus (low RH) in hybrid aspen (Populus tremula L. × P. tremuloides Michx.) coppice growing in field conditions. Artificially elevated RH reduced air vapour pressure deficit by 5%–10% and altered stomatal sensitivity; trees grown under high RH exhibited stronger stomatal response to decreasing air humidity. We found no difference in mean stomatal pore length between treatments and a small decline in stomatal density under humidification. The lack of correlation between stomatal sensitivity and morphological traits suggests that stomatal sensitivity was unaffected by stomatal morphology. In light of rising atmospheric humidity predicted for high latitudes, strict stomatal control over water loss might be beneficial for trees if drought events become more frequent in the future. However, our experiment revealed that about two-thirds of the leaf-to-air vapour pressure difference (VPDL) response curves demonstrated the opposite pattern, i.e., stomatal opening in response to increasing VPDL. Strict stomatal regulation is probably not beneficial to fast-growing aspen coppice under low RH, as this trait may restrict their carbon gain and growth rate.

Innovative physiological indicators for drought stress in banana

2020 ◽  
Author(s):  
Mathilde Vantyghem ◽  
Roel Merckx ◽  
Rebecca Hood-Nowotny ◽  
Bert Stevens ◽  
Christian Resch ◽  
...  
Keyword(s):  
Drought Stress ◽  
Carbon Isotope ◽  
Management Practices ◽  
Smallholder Farmers ◽  
Stomatal Closure ◽  
Stable Carbon Isotope ◽  
Leaf Temperature ◽  
Field Conditions ◽  
Infrared Thermometer ◽  
Mother Plants

<p>Banana is a very important crop in East-Africa, serving as a staple for millions of smallholder farmers. Aside from pests and diseases, lack of water is the major constraint to production. Climate change is expected to aggravate these problems, creating a need for improved resilience and better management practices. A major obstacle to the development and evaluation of such practices is the difficulty to measure drought stress in the field. In this research, we investigate physiological parameters that can provide information on drought stress in banana under field conditions. We evaluate the use of stable carbon isotope ratios (δ<sup>13</sup>C) and leaf temperature as indicators for stress, the former ones not well-established for banana. Leaf temperature is known to increase under drought stress due to stomatal closure. The existing methods to measure leaf temperature are however expensive and their use is limited to small greenhouse set-ups. In this research, we employ an infrared thermometer (±1°C) for temperature measurement under field conditions. The experimental set-up consists of a banana field trial with a blocked design (irrigated and rainfed treatments) in the Kilimanjaro region, Tanzania. Leaf samples for isotope analysis were taken from mature plants (mother plants) and the main on-growing sucker (daughter plants) in August 2019, during the dry season. Leaf temperature was monitored throughout the day. Results show significantly higher δ<sup>13</sup>C ratios in rainfed plants, compared to irrigated ones, indicating more drought stress. Within both groups, mother plants have higher δ<sup>13</sup>C ratios than daughter plants. At dawn, leaf temperature was similar for all treatments. During the day, rainfed banana plant leaf temperature increased 7°C more than in their irrigated counterparts. Daughter plants remained cooler than mother plants in both treatments. Leaf temperature and δ<sup>13</sup>C showed a strong correlation. While carbon isotope signatures are a known proxy, our results suggest that leaf temperature is a an easily measurable indicator of drought stress as well. The infrared thermometer is cheap, convenient to use in the field and provides in-situ information. Leaf temperature has an enormous potential as a drought stress sensor in banana, as well as in other plants. Our research will further optimize both methods for drought stress evaluation. This will facilitate management comparisons in the future as well as variety screening, eventually contributing to more resilient banana production systems.</p>

Elevated CO2 increases the leaf temperature of two glasshouse-grown C4 grasses

2002 ◽  
Vol 29 (12) ◽  
pp. 1377 ◽  
Author(s):  
Katharina Siebke ◽  
Oula Ghannoum ◽  
Jann P. Conroy ◽  
Susanne von Caemmerer
Keyword(s):  
Gas Exchange ◽  
Elevated Co2 ◽  
Leaf Gas Exchange ◽  
Stomatal Closure ◽  
Co2 Assimilation ◽  
High Irradiance ◽  
Leaf Temperature ◽  
C4 Grasses ◽  
Co2 Partial Pressure ◽  
The Difference

This study investigates the effect of elevated CO2 partial pressure (pCO2)-induced stomatal closure on leaf temperature and gas exchange of C4 grasses. Two native Australian C4 grasses, Astrebla lappacea (Lindl.) Domin and Bothriochloa bladhii Kuntze, were grown at three different pCO2 (35, 70 and 120 Pa) in three matched, temperature-controlled glasshouse compartments. The difference between leaf and air temperature (ΔT) was monitored diurnally with thermocouples. ΔT increased with both step-increases of ambient pCO2. Average noon leaf temperature increased by 0.4 and 0.3°C for A. lappacea with the 35–70 and 70–120 Pa steps of pCO2 elevation, respectively. For B. bladhii, the increases were 0.5°C for both pCO2 steps. ΔT was strongly dependent on irradiance, pCO2 and air humidity. Leaf gas exchange was measured at constant temperature and high irradiance at the three growth pCO2. Under these conditions, CO2 assimilation saturated at 70 Pa, while stomatal conductance decreased by the same extent (0.58-fold) with both step-increases in pCO2, suggesting that whole-plant water use efficiency of C4 grasses would increase beyond a doubling of ambient pCO2. The ratio of intercellular to ambient pCO2 was not affected by short- or long-term doubling or near-tripling of pCO2, in either C4 species when measured under standard conditions.

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