Dissecting the combined effects of air temperature and relative humidity on water‐use efficiency of barley under drought stress

Zhang, Peng; Yang, Xin; Chen, Yi-Ting; Wei, Zhenhua; Liu, Fulai

doi:10.1111/jac.12475

Cited by 10 publications

(8 citation statements)

References 72 publications

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“…S7). Reduced g s and photosynthesis due to high VPD can happen in well-irrigated plants with high temperatures impacting enzymatic activity and increasing photorespiration above a specific threshold (Zhang et al, 2021). More recently, Schönbeck et al (2022) also showed that high VPD induced loss of xylem conductivity in well-irrigated plants, suggesting that reduced photosynthesis as a response to high VPD and temperature could prevent xylem embolism.…”

Section: Discussionmentioning

confidence: 99%

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Absence of canopy temperature variation despite stomatal adjustment in Pinus sylvestris under multidecadal soil moisture manipulation

Gauthey,

Bachofen,

Deluigi

et al. 2023

New Phytologist

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Summary Global warming and droughts push forests closer to their thermal limits, altering tree carbon uptake and growth. To prevent critical overheating, trees can adjust their thermotolerance (Tcrit), temperature and photosynthetic optima (Topt and Aopt), and canopy temperature (Tcan) to stay below damaging thresholds. However, we lack an understanding of how soil droughts affect photosynthetic thermal plasticity and Tcan regulation. In this study, we measured the effect of soil moisture on the seasonal and diurnal dynamics of net photosynthesis (A), stomatal conductance (gs), and Tcan, as well as the thermal plasticity of photosynthesis (Tcrit, Topt, and Aopt), over the course of 1 yr using a long‐term irrigation experiment in a drought‐prone Pinus sylvestris forest in Switzerland. Irrigation resulted in higher needle‐level A, gs, Topt, and Aopt compared with naturally drought‐exposed trees. No daily or seasonal differences in Tcan were observed between treatments. Trees operated below their thermal thresholds (Tcrit), independently of soil moisture content. Despite strong Tcan and Tair coupling, we provide evidence that drought reduces trees' temperature optimum due to a substantial reduction of gs during warm and dry periods of the year. These findings provide important insights regarding the effects of soil drought on the thermal tolerance of P. sylvestris.

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Section: Discussionmentioning

confidence: 99%

“…S7). Reduced g s and photosynthesis due to high VPD can happen in well‐irrigated plants with high temperatures impacting enzymatic activity and increasing photorespiration above a specific threshold (Zhang et al ., 2021). More recently, Schönbeck et al .…”

Section: Discussionmentioning

confidence: 99%

Absence of canopy temperature variation despite stomatal adjustment in Pinus sylvestris under multidecadal soil moisture manipulation

Gauthey,

Bachofen,

Deluigi

et al. 2023

New Phytologist

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“…On the other hand, high air relative humidity will alleviate partly this negative impact by decreasing VPD (Grossiord et al ., 2020). Therefore, the overall impact depends on the tradeoffs between the effects of high dry bulb temperature and high humidity on crop productivity (Grossiord et al ., 2020; Zhang et al ., 2021a). Moreover, how deadly humid heatwaves will impact the diversity and conservation of crop species still needs further investigation.…”

Section: Discussionmentioning

confidence: 99%

“…During deadly humid heatwaves, extreme high temperature results in high vapour pressure deficit (VPD), which reduce crop yield by increasing leaf transpiration and decreasing photosynthetic water‐use efficiency (Rashid et al ., 2018; Zhang et al ., 2021a). On the other hand, high air relative humidity will alleviate partly this negative impact by decreasing VPD (Grossiord et al ., 2020).…”

Section: Discussionmentioning

confidence: 99%

The emergence of prolonged deadly humid heatwaves

Wang

et al. 2022

Intl Journal of Climatology

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Deadly humid heat conditions exceeding human thermoregulatory capacity have been reported; however, whether and where the deadly humid heat events occur consecutively across the land surface are largely unknown. We calculate the maximum consecutive days of deadly humid heat, defined as daily maximum wet-bulb temperature (TWmax) ≥35 C, for observations of 9,278 meteorological stations and for simulations of 14 global climate models. We further define short and long deadly humid heatwaves as a period of 3-4 and ≥5 consecutive days with daily TWmax ≥35 C, respectively. Our analyses show that six stations in some subtropical regions have experienced deadly humid heat with daily TWmax ≥35 C, but only occurs in individual days. Deadly humid heatwaves increase exponentially as the global mean temperature rising. When limiting global warming within 1.5 C, long deadly humid heatwaves will not occur across the land surface, and short deadly humid heatwaves will only emerge in some drylands but not in humid areas. Under 2 C warming, 0.09% of the global land, 0.42% of the human population, and 0.56% of the global centres of crop diversity are projected to be exposed to long deadly humid heatwaves. Meanwhile, 18% of the deadly humid heatwaves lasting ≥3 consecutive days will occur in humid areas; the fractions are projected to rapidly increase in humid areas as temperature rising further. At the end of the century, the percentage of land areas and human population exposed to deadly humid heatwaves lasting ≥3 consecutive days are expected to be 76-times higher than that under 1.5 C warming level.Our finding suggests that keeping global warming within 1.5 C will significantly constrain the emergence of prolonged deadly humid heatwaves and thus reduce the risk of the human population especially outdoor agricultural workers.climate warming, deadly humid heatwaves, exposure, wet bulb temperature | INTRODUCTIONExtreme humid heat is one of the most dangerous natural hazards (Wehner et al., 2016) and is recognized as an immediate threat to humans health and survivability (Meehl and Tebaldi, 2004;Sherwood and Huber, 2010;Mora et al., 2017; Mitchell, 2021). Compared with extreme dry heat, during extreme humid heatwaves, the threshold that temperature becomes deadly decreases with rising environment relative humidity (Pal and Eltahir, 2016;Xiang-Sheng Wang and Lei He are co-first authors.

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“…Similarly, the transpiration rate response to soil drying is exacerbated by increasing VPD (meaning that plants would decrease the transpiration rate at relatively higher soil moisture levels if the VPD is high; e.g. Devi and Reddy, 2020 ; P. Zhang et al , 2021 , 2022 ). These results are easily predicted using the water demand–supply framework, as that implemented in Wankmüller and Carminati (2022) , and illustrated in Fig.…”

Section: Synthesis: Combined Response To High Vapor Pressure Deficit ...mentioning

confidence: 99%

Transpiration response to soil drying versus increasing vapor pressure deficit in crops: physical and physiological mechanisms and key plant traits

Koehler

Wankmüller

Sadok

et al. 2023

Journal of Experimental Botany

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The water deficit experienced by crops is a function of atmospheric water demand (vapor pressure deficit, VPD) and soil water supply over the whole crop cycle. We summarize typical transpiration response patterns to soil and atmospheric drying and the sensitivity to plant hydraulic traits. We explain the transpiration response patterns using a soil-plant hydraulic framework. In both cases of drying, stomatal closure is triggered by limitations in soil-plant hydraulic conductance. However, traits impacting the transpiration response differ between the two drying processes and act at different time scales. A low plant hydraulic conductance triggers an earlier restriction in transpiration during increasing VPD. During soil drying, the impact of the plant hydraulic conductance is less obvious. It is rather a decrease in the belowground hydraulic conductance (related to soil hydraulic properties and root length density) that is involved in transpiration downregulation. The transpiration response to increasing VPD has a daily time scale. In the case of soil drying, it acts on a seasonal scale. Varieties that are conservative in water use on a daily scale may not be conservative over larger time scales (e.g. during soil drying). This potential independency of strategies needs to be considered in environmental-specific breeding for yield-based drought tolerance.

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Dissecting the combined effects of air temperature and relative humidity on water‐use efficiency of barley under drought stress

Cited by 10 publications

References 72 publications

Absence of canopy temperature variation despite stomatal adjustment in Pinus sylvestris under multidecadal soil moisture manipulation

Absence of canopy temperature variation despite stomatal adjustment in Pinus sylvestris under multidecadal soil moisture manipulation

The emergence of prolonged deadly humid heatwaves

Transpiration response to soil drying versus increasing vapor pressure deficit in crops: physical and physiological mechanisms and key plant traits

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