Abstract
Abstract Background and aims A better understanding of plant carbon assimilation, water status and photosystem performance responses to combined heat and drought stress would help to optimize grapevine management under such limiting conditions. Methods Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines. Results Photosynthesis and stomatal conductance in HW vines increased during the morning and dropped in the afternoon with respect to CW vines. Daily plant transpiration in HW almost doubled that of CW vines. When grapevines were already exposed to drought, the effects of the heat wave were negligible, with HD plants showing similar leaf photosynthesis and transpiration to their CD counterparts. Heat, but not drought stress, decreased the maximum (Fv/Fm) and effective photochemical quantum yield of PSII (φPSII), and also affected the use of absorbed energy. HW plants dissipated more radiative energy as heat, a protective mechanism of the photosystem, while HD vines increased the energy dissipated by non-regulated non-photochemical pathways, which might lead to photoinhibition damages. The different behavior could be due to the enhanced transpiration rate and consequent decrease in leaf temperature in HW as compared to HD vines. After the heat wave, only HW vines recovered the afternoon values of photosynthesis, stomatal conductance and φPSII to similar levels as those in CW vines. Conclusion Drought had a more significant effect than heat stress on photosynthesis, stomatal conductance and transpiration. The combined heat and drought stress, however, increased the proportion of energy lost by the leaves through harmful non-regulated dissipative pathways. With adequate soil water availability, grapevines withstood the heat wave period through an increase in leaf transpiration, which decreased leaf temperature and protected the PSII from heat damage.
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Claims 10
Claim · model-written summary
Heat in well-watered vines increased photosynthesis and stomatal conductance during the morning.
- Treatment
- heated well-watered (HW)e0
- Outcome
- Photosynthesis and stomatal conductancee1
- Direction
- increasede1
- Qualifier
- during the morninge1
- Comparator
- non-heated well-watered (CW)e0
VitisOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e1“Photosynthesis and stomatal conductance in HW vines increased during the morning and dropped in the afternoon with respect to CW vines”
Claim · model-written summary
Heat in well-watered vines decreased photosynthesis and stomatal conductance in the afternoon.
- Treatment
- heated well-watered (HW)e0
- Outcome
- Photosynthesis and stomatal conductancee1
- Direction
- droppede1
- Qualifier
- in the afternoone1
- Comparator
- non-heated well-watered (CW)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e1“Photosynthesis and stomatal conductance in HW vines increased during the morning and dropped in the afternoon with respect to CW vines”
Claim · model-written summary
Heat in well-watered vines almost doubled daily plant transpiration relative to non-heated well-watered vines.
- Treatment
- heated well-watered (HW)e0
- Outcome
- Daily plant transpiratione2
- Direction
- almost doublede2
- Comparator
- non-heated well-watered (CW)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e2“Daily plant transpiration in HW almost doubled that of CW vines”
Claim · model-written summary
When already drought-exposed, the heat wave had negligible effects, with similar leaf photosynthesis and transpiration to non-heated dry vines.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e3“When grapevines were already exposed to drought, the effects of the heat wave were negligible, with HD plants showing similar leaf photosynthesis and transpiration to their CD counterparts”
Claim · model-written summary
Heat decreased the maximum and effective photochemical quantum yield of PSII, unlike drought stress.
- Treatment
- Heate4
- Outcome
- maximum (Fv/Fm) and effective photochemical quantum yield of PSII (φPSII)e4
- Direction
- decreasede4
- Comparator
- drought stresse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e4“Heat, but not drought stress, decreased the maximum (Fv/Fm) and effective photochemical quantum yield of PSII (φPSII), and also affected the use of absorbed energy”
Claim · model-written summary
Heated well-watered vines dissipated more radiative energy as heat, a protective mechanism of the photosystem.
- Treatment
- heated well-watered (HW)e0
- Outcome
- radiative energye5
- Direction
- moree5
- Qualifier
- a protective mechanism of the photosysteme5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e5“HW plants dissipated more radiative energy as heat, a protective mechanism of the photosystem”
Claim · model-written summary
Heated drought-stressed vines increased energy dissipated by non-regulated non-photochemical pathways, which might lead to photoinhibition damage.
- Treatment
- heated drought-stressed (HD)e0
- Outcome
- energy dissipated by non-regulated non-photochemical pathwayse6
- Direction
- increasede6
- Qualifier
- which might lead to photoinhibition damagese6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e6“HD vines increased the energy dissipated by non-regulated non-photochemical pathways, which might lead to photoinhibition damages”
Claim · model-written summary
After the heat wave, only heated well-watered vines recovered afternoon photosynthesis, stomatal conductance and φPSII to levels similar to non-heated well-watered vines.
- Treatment
- heated well-watered (HW)e0
- Outcome
- afternoon values of photosynthesis, stomatal conductance and φPSIIe7
- Direction
- recoverede7
- Qualifier
- After the heat wavee7
- Comparator
- non-heated well-watered (CW)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e7“After the heat wave, only HW vines recovered the afternoon values of photosynthesis, stomatal conductance and φPSII to similar levels as those in CW vines”
Claim · model-written summary
Drought had a more significant effect than heat stress on photosynthesis, stomatal conductance and transpiration.
- Treatment
- Droughte7
- Outcome
- photosynthesis, stomatal conductance and transpiratione7
- Direction
- more significant effecte7
- Comparator
- heat stresse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e7“Drought had a more significant effect than heat stress on photosynthesis, stomatal conductance and transpiration”
Claim · model-written summary
Transpiration-driven leaf cooling protected PSII from heat damage when soil water was adequate.
- Outcome
- protected the PSII from heat damagee7
- Qualifier
- through an increase in leaf transpiration, which decreased leaf temperaturee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (T max = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines”
e7“With adequate soil water availability, grapevines withstood the heat wave period through an increase in leaf transpiration, which decreased leaf temperature and protected the PSII from heat damage”
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See all 14 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.