Abstract
The influence of long-term water deficit on photosynthesis, electron transport and carbon metabolism of sunflower leaves has been examined. Water deficit was imposed from flower bud formation up to the stage of full flowering in the field on two sunflower hybrids with different drought tolerance. CO2 assimilation and stomatal conductance of the intact leaves, determined at atmospheric CO2 and full sunlight (1500–2000 µmol quanta m−2 s−1), decreased with water deficit. Maximum quantum efficiency of PSII (Fv/Fm) and relative quantum yield of PSII (ΦII) determined under similar experimental conditions, did not change significantly in severely stressed leaves. The strong inhibition of the plateau region of the light response curve, determined at high CO2 (5%) in water-deficient sunflower leaves, indicates that photosynthesis is also limited by non-stomatal factors. The decreased slope and the plateau of the CO2 response curves show that the capacity of carboxylation and RuBP regeneration decreased in severely stressed intact leaves. Rubisco specific activity decreased in severely stressed leaves, but Rubisco content increased under prolonged drought. The increase of Rubisco content was significantly higher in leaves of the drought-tolerant sunflower hybrid indicating that a higher Rubisco content could be one factor in conferring better acclimation and higher drought tolerance.
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Claims 8
Claim · model-written summary
CO2 assimilation and stomatal conductance decreased with water deficit.
- Taxon
- sunflower
Helianthus annuust0 - Material
- two sunflower hybrids with different drought tolerancee2
- Treatment
- water deficite1
- Outcome
- CO2 assimilation and stomatal conductancee1
- Direction
- decreasede1
- Setting
- in the fielde2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“two sunflower hybrids”
e1“CO2 assimilation and stomatal conductance of the intact leaves, determined at atmospheric CO2 and full sunlight (1500–2000 µmol quanta m−2 s−1), decreased with water deficit”
e2“Water deficit was imposed from flower bud formation up to the stage of full flowering in the field on two sunflower hybrids with different drought tolerance”
Claim · model-written summary
Maximum quantum efficiency of PSII and relative quantum yield of PSII did not change significantly in severely stressed leaves.
- Taxon
- sunflowerHelianthus annuust0
- Treatment
- severely stressed leavese3
- Outcome
- Maximum quantum efficiency of PSII (Fv/Fm) and relative quantum yield of PSII (ΦII)e3
- Direction
- no_changeinferrede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“two sunflower hybrids”
e3“Maximum quantum efficiency of PSII (Fv/Fm) and relative quantum yield of PSII (ΦII) determined under similar experimental conditions, did not change significantly in severely stressed leaves”
Claim · model-written summary
Photosynthesis in water-deficient sunflower leaves is limited by non-stomatal factors.
- Taxon
- sunflowerHelianthus annuust0
- Treatment
- water-deficiente4
- Outcome
- photosynthesise4
- Qualifier
- non-stomatal factorse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“two sunflower hybrids”
e4“The strong inhibition of the plateau region of the light response curve, determined at high CO2 (5%) in water-deficient sunflower leaves, indicates that photosynthesis is also limited by non-stomatal factors”
Claim · model-written summary
Capacity of carboxylation and RuBP regeneration decreased in severely stressed intact leaves.
- Taxon
- sunflowerHelianthus annuust0
- Treatment
- severely stressed intact leavese5
- Outcome
- capacity of carboxylation and RuBP regeneratione5
- Direction
- decreasede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“two sunflower hybrids”
e5“The decreased slope and the plateau of the CO2 response curves show that the capacity of carboxylation and RuBP regeneration decreased in severely stressed intact leaves”
Claim · model-written summary
Rubisco specific activity decreased in severely stressed leaves.
- Taxon
- sunflowerHelianthus annuust0
- Treatment
- severely stressed leavese6
- Gene
- Rubiscoe6
- Outcome
- Rubisco specific activitye6
- Direction
- decreasede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“two sunflower hybrids”
e6“Rubisco specific activity decreased in severely stressed leaves, but Rubisco content increased under prolonged drought”
Claim · model-written summary
Rubisco content increased under prolonged drought.
- Taxon
- sunflowerHelianthus annuust0
- Treatment
- prolonged droughte6
- Gene
- Rubiscoe6
- Outcome
- Rubisco contente6
- Direction
- increasede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“two sunflower hybrids”
e6“Rubisco specific activity decreased in severely stressed leaves, but Rubisco content increased under prolonged drought”
Claim · model-written summary
Increase of Rubisco content was significantly higher in the drought-tolerant sunflower hybrid.
- Taxon
- sunflowerHelianthus annuust0
- Material
- drought-tolerant sunflower hybride7
- Gene
- Rubiscoe7
- Outcome
- increase of Rubisco contente7
- Direction
- highere7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“two sunflower hybrids”
e7“The increase of Rubisco content was significantly higher in leaves of the drought-tolerant sunflower hybrid”
Claim · model-written summary
A higher Rubisco content could be one factor conferring better acclimation and higher drought tolerance.
- Taxon
- sunflowerHelianthus annuust0
- Gene
- Rubiscoe7
- Outcome
- better acclimation and higher drought tolerancee7
- Qualifier
- higher Rubisco contente7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“two sunflower hybrids”
e7“indicating that a higher Rubisco content could be one factor in conferring better acclimation and higher drought tolerance”
The same questions in other papers
drought · physiology: photosynthesis · Helianthus annuus (common sunflower)Positive and negative results
2 papers in the same direction as this paper · 22 in the opposite direction
- negative
- negative
- negative
21 papers more in this group
See all 25 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.