Transient Heat Waves May Affect the Photosynthetic Capacity of Susceptible Wheat Genotypes Due to Insufficient Photosystem I Photoprotection

We assessed the photosynthetic responses of eight wheat varieties in conditions of a simulated heat wave in a transparent plastic tunnel for one week. We found that high temperatures (up to 38 °C at midday and above 20 °C at night) had a negative effect on the photosynthetic functions of the plants and provided differentiation of genotypes through sensitivity to heat. Measurements of gas exchange showed that the simulated heat wave led to a 40% decrease in photosynthetic activity on average in comparison to the control, with an unequal recovery of individual genotypes after a release from stress. Our results indicate that the ability to recover after heat stress was associated with an efficient regulation of linear electron transport and the prevention of over-reduction in the acceptor side of photosystem I.

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The Role of Abscisic Acid in the Response of Two Different Wheat Varieties to Water Deficit

Zeitschrift für Naturforschung C ◽

10.1515/znc-2009-1-214 ◽

2009 ◽

Vol 64 (1-2) ◽

pp. 77-84 ◽

Cited By ~ 1

Author(s):

Hala Ezzat Mohamed ◽

Ghada Saber M. Ismail

Keyword(s):

Abscisic Acid ◽

Drought Stress ◽

Transpiration Rate ◽

Electrolyte Leakage ◽

Photosynthetic Activity ◽

Recovery Period ◽

Wheat Varieties ◽

Relative Water ◽

Negative Effect

The changes in plant growth, transpiration rate, photosynthetic activity, plant pigments, electrolyte leakage, H2O2 content, lipid peroxidation, catalase activity and endogenous content of abscisic acid (ABA) were followed in the leaves of two wheat varieties (sakha 93 and 94) during drought stress and subsequent rehydration. Drought stress caused several inhibitory changes in the growth of both wheat varieties, particularly in sakha 94. Exogenous ABA treatment improved the growth of sakha 93 plants as indicated by a higher relative water content, transpiration rate and lower electrolyte leakage and also enhanced the growth during the recovery period. Such improvement may be the result of the induction of enzymatic (catalase) and non-enzymatic (carotenoid) systems. ABA treatment did not ameliorate the negative effect of drought on the growth of sakha 94.

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Bud dormancy in apple trees after thermal fluctuations

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x2014000600007 ◽

2014 ◽

Vol 49 (6) ◽

pp. 457-464 ◽

Cited By ~ 8

Author(s):

Rafael Anzanello ◽

Flávio Bello Fialho ◽

Henrique Pessoa dos Santos ◽

Homero Bergamaschi ◽

Gilmar Arduino Bettio Marodin

Keyword(s):

Heat Wave ◽

Prediction Models ◽

Heat Waves ◽

Experimental Period ◽

Thermal Fluctuations ◽

Bud Dormancy ◽

Temperature Cycle ◽

Apple Trees ◽

Negative Effect ◽

In The Beginning

The objective of this work was to evaluate the effect of heat waves on the evolution of bud dormancy, in apple trees with contrasting chilling requirements. Twigs of 'Castel Gala' and 'Royal Gala' were collected in orchards in Papanduva, state of Santa Catarina, Brazil, and were exposed to constant (3°C) or alternating (3 and 15°C for 12/12 hours) temperature, combined with zero, one or two days a week at 25°C. Two additional treatments were evaluated: constant temperature (3°C), with a heat wave of seven days at 25°C, in the beginning or in the middle of the experimental period. Periodically, part of the twigs was transferred to 25°C for daily budburst evaluation of apical and lateral buds. Endodormancy (dormancy induced by cold) was overcome with less than 330 chilling hours (CH) of constant cold in 'Castel Gala' and less than 618 CH in 'Royal Gala'. A daily 15°C-temperature cycle did not affect the endodormancy process. Heat waves during endodormancy resulted in an increased CH to achieve bud requirements. The negative effect of high temperature depended on the lasting of this condition. Chilling was partly cancelled during dormancy when the heat wave lasted 36 continuous hours or more. Therefore, budburst prediction models need adjustments, mainly for regions with mild and irregular winters, such as those of Southern Brazil.

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Publisher Correction: Dynamic thylakoid stacking and state transitions work synergistically to avoid acceptor-side limitation of photosystem I

Nature Plants ◽

10.1038/s41477-021-00859-4 ◽

2021 ◽

Vol 7 (2) ◽

pp. 238-238

Author(s):

Christopher Hepworth ◽

William H. J. Wood ◽

Tom Z. Emrich-Mills ◽

Matthew S. Proctor ◽

Stuart Casson ◽

...

Keyword(s):

Photosystem I ◽

State Transitions ◽

Acceptor Side ◽

Thylakoid Stacking

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Abstract P069: Heat, Heat Waves and Hospital Admissions in Indianapolis, Indiana

Circulation ◽

10.1161/circ.135.suppl_1.p069 ◽

2017 ◽

Vol 135 (suppl_1) ◽

Author(s):

Yi Wang

Keyword(s):

Myocardial Infarction ◽

Heart Failure ◽

Relative Risk ◽

Heat Wave ◽

Hospital Admissions ◽

Heat Waves ◽

Global Climate ◽

Extreme Heat ◽

Apparent Temperature ◽

The Impact

Background: The association between heat and hospital admissions is well studied, but in Indiana where the regulatory agencies cites lack of evidence for global climate change, local evidence of such an association is critical for Indiana to mitigate the impact of increasing heat. Methods: Using a distributed-lag non-linear model, we studied the effects of moderate (31.7 °C or 90 th percentile of daily mean apparent temperature (AT)), severe (33.5 °C or 95 th percentile of daily mean apparent temperature (AT)) and extreme (36.4 °C or 99 th percentile of AT) heat on hospital admissions (June-August 2007-2012) for cardiovascular (myocardial infarction, myocardial infarction, heart failure) and heat-related diseases in Indianapolis, Indiana located in Marion County. We also examined the added effects of moderate heat waves (AT above the 90 th percentile lasting 2-6 days), severe heat waves (AT above the 95 th percentile lasting 2-6 days) and extreme heat waves (AT above the 99 th percentile lasting 2-6 days). In sensitivity analysis, we tested robustness of our results to 1) different temperature and lag structures and 2) temperature metrics (daily min, max and diurnal temperature range). Results: The relative risks of moderate heat, relative to 29.2°C (75 th percentile of AT), on admissions for cardiovascular disease (CVD), myocardial infarction (MI), heart failure (HF), and heat-related diseases (HD) were 0.98 (0.67, 1.44), 6.28 (1.48, 26.6), 1.38 (0.81, 2.36) and 1.73 (0.58, 5.11). The relative risk of severe heat on admissions for CVD, MI, HF, and HD were 0.93 (0.60, 1.43), 4.46 (0.85, 23.4), 1.30 (0.72, 2.34) and 2.14 (0.43, 10.7). The relative risk of extreme heat were 0.79 (0.26, 2.39), 0.11 (0.087, 1.32), 0.68 (0.18, 2.61), and 0.32 (0.005, 19.5). We also observed statistically significant added effects of moderate heat waves lasting 4 or 6 days on hospital admission for MI and HD and extreme heat waves lasting 4 days on hospital admissions for HD. Results were strengthened for people older than 65. Conclusions: Moderate heat wave lasting 4-6 days were associated with increased hospital admissions for MI and HD diseases and extreme heat wave lasting 4 days were associated with increased admissions for HD.

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Heat waves in Berlin and Potsdam, Germany – Long‐term trends and comparison of heat wave definitions from 1893 to 2017

International Journal of Climatology ◽

10.1002/joc.5962 ◽

2018 ◽

Vol 39 (4) ◽

pp. 2422-2437 ◽

Cited By ~ 14

Author(s):

Daniel Fenner ◽

Achim Holtmann ◽

Alexander Krug ◽

Dieter Scherer

Keyword(s):

Heat Wave ◽

Heat Waves ◽

Long Term Trends

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Photosynthetic Activity of Chloroplasts Isolated From Bermudagrass (Cynodon dactylon L.), a Species With a High Photosynthetic Capacity

PLANT PHYSIOLOGY ◽

10.1104/pp.44.5.649 ◽

1969 ◽

Vol 44 (5) ◽

pp. 649-654 ◽

Cited By ~ 29

Author(s):

T. M. Chen ◽

R. H. Brown ◽

C. C. Black

Keyword(s):

Photosynthetic Activity ◽

Cynodon Dactylon ◽

Photosynthetic Capacity ◽

High Photosynthetic Capacity

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Using Forecast and Observed Weather Data to Assess Performance of Forecast Products in Identifying Heat Waves and Estimating Heat Wave Effects on Mortality

Environmental Health Perspectives ◽

10.1289/ehp.1306858 ◽

2014 ◽

Vol 122 (9) ◽

pp. 912-918 ◽

Cited By ~ 21

Author(s):

Kai Zhang ◽

Yeh-Hsin Chen ◽

Joel D. Schwartz ◽

Richard B. Rood ◽

Marie S. O’Neill

Keyword(s):

Heat Wave ◽

Heat Waves ◽

Weather Data ◽

Wave Effects

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Could aerosol emissions be used for regional heat wave mitigation?

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-23793-2012 ◽

2012 ◽

Vol 12 (9) ◽

pp. 23793-23828

Author(s):

D. N. Bernstein ◽

J. D. Neelin ◽

Q. B. Li ◽

D. Chen

Keyword(s):

Los Angeles ◽

Heat Wave ◽

Heat Waves ◽

Regional Scale ◽

Middle Part ◽

Emission Rates ◽

Sulfate Aerosols ◽

Geographical Differences ◽

Aerosol Emission ◽

Trade Offs

Abstract. Geoengineering applications by injection of sulfate aerosols into the stratosphere are under consideration as a measure of last resort to counter global warming. Here adaptation to a potential regional scale application to offset the impacts of heat waves is critically examined. The effect of regional scale sulfate aerosol emission over California in each of two days of the July 2006 heat wave using the Weather Research and Forecasting model with fully coupled chemistry (WRF-Chem) is used to quantify potential reductions in surface temperature as a function of emission rates in the lower stratosphere. Over the range considered, afternoon temperature reductions scale almost linearly with injections. Local meteorological factors yield geographical differences in surface air temperature sensitivity. For emission rates of approximately 30 μg m−2 s−1 of sulfate aerosols (with standard WRF-Chem size distribution) over the region, temperature decreases of around 7 °C result during the middle part of the day over the Central Valley, one of the hardest hit by the heat wave. Regions more ventilated with oceanic air such as Los Angeles have slightly smaller reductions. The length of the hottest part of the day is also reduced. Advection effects on the aerosol cloud must be more carefully forecast for smaller injection regions. Verification of the impacts could be done via measurements of differences in reflected and surface downward shortwave. Such regional geoengineering applications with specific near-term target effects but smaller cost and side effects could potentially provide a means of testing larger scale applications. However, design trade-offs differ from global applications and the size of the required injections and the necessity of injection close to the target region raise substantial concerns. The evaluation of this regional scale application is thus consistent with global model evaluations emphasizing that mitigation via reduction of fossil fuels remains preferable to considering geoengineering with sulfate aerosols.

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Disentangling the response of forest and grassland energy exchange to heatwaves under idealized land–atmosphere coupling

Biogeosciences Discussions ◽

10.5194/bgd-11-5969-2014 ◽

2014 ◽

Vol 11 (4) ◽

pp. 5969-5995

Author(s):

C. C. van Heerwaarden ◽

A. J. Teuling

Keyword(s):

Heat Wave ◽

Heat Waves ◽

Dynamic Properties ◽

Sensible Heat Flux ◽

Early Morning ◽

Stomatal Resistance ◽

Heat Fluxes ◽

Sensible Heat ◽

Area Index ◽

Wave Conditions

Abstract. This study investigates the difference in land–atmosphere interactions between grassland and forest during typical heat wave conditions in order to understand the controversial results of Teuling et al. (2010) (T10, hereafter), who have found the systematic occurrence of higher sensible heat fluxes over forest than over grassland during heat wave conditions. With a simple, but accurate coupled land–atmosphere model, we are able to reproduce the findings of T10 for both normal summer and heat wave conditions, and to carefully explore the sensitivity of the coupled land–atmosphere system to changes in incoming radiation and early-morning temperature. Our results emphasize the importance of fast processes during the onset of heat waves, since we are able to explain the results of T10 without having to take into account changes in soil moisture. In order to disentangle the contribution of differences in several static and dynamic properties between forest and grassland, we have performed an experiment in which new land use types are created that are equal to grassland, but with one of its properties replaced by that of forest. From these, we conclude that the closure of stomata in the presence of dry air is by far the most important process in creating the different behavior of grassland and forest during the onset of a heat wave. However, we conclude that for a full explanation of the results of T10 also the other properties (albedo, roughness and the ratio of minimum stomatal resistance to leaf-area index) play an important, but indirect role; their influences mainly consist of strengthening the feedback that leads to the closure of the stomata by providing more energy that can be converted into sensible heat. The model experiment also confirms that, in line with the larger sensible heat flux, higher atmospheric temperatures occur over forest.

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Evaluating sub-seasonal heatwave reforecasts of the ECMWF over Europe

10.5194/ems2021-146 ◽

2021 ◽

Author(s):

Natalia Korhonen ◽

Otto Hyvärinen ◽

Matti Kämäräinen ◽

Kirsti Jylhä

Keyword(s):

Heat Wave ◽

Heat Waves ◽

Lead Times ◽

Weather Forecasts ◽

Wave Forecast ◽

Extended Range ◽

Hot Days ◽

Medium Range ◽

Summer Temperatures

Severe heatwaves have harmful impacts on ecosystems and society. Early warning of heat waves help with decreasing their harmful impact. Previous research shows that the Extended Range Forecasts (ERF) of the European Centre for Medium-Range Weather Forecasts (ECMWF) have over Europe a somewhat higher reforecast skill for extreme hot summer temperatures than for long-term mean temperatures. Also it has been shown that the reforecast skill of the ERFs of the ECMWF was strongly increased by the most severe heat waves (the European heatwave 2003 and the Russian heatwave 2010).Our aim is to be able to estimate the skill of a heat wave forecast at the time the forecast is given. For that we investigated the spatial and temporal reforecast skill of the ERFs of the ECMWF to forecast hot days (here defined as a day on which the 5 days running mean surface temperature is above its summer 90th percentile) in the continental Europe in summers 2000-2019. We used the ECMWF 2-meter temperature reforecasts and verified them against the ERA5 reanalysis. The skill of the hot day reforecasts was estimated by the symmetric extremal dependence index (SEDI) which considers both hit rates and false alarm rates of the hot day forecasts. Further, we investigated the skill of the heatwave reforecasts based on at which time steps of the forecast the hot days were forecasted. We found that on the mesoscale (horizontal scale of ~500 km) the ERFs of the ECMWF were most skillful in predicting the life cycle of a heat wave (lasting up to 25 days) about a week before its start and during its course. That is, on the mesoscale those reforecasts, in which hot day(s) were forecasted to occur during the first 7&#8230;11 days, were more skillful on lead times up to 25 days than the rest of the heat wave forecasts. This finding is valuable information, e.g., in the energy and health sectors while preparing for a coming heat wave.The work presented here is part of the research project HEATCLIM (Heat and health in the changing climate) funded by the Academy of Finland.

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