Abstract
Abstract Sunburn has become one of the major threats to apple fruit production in South Africa and other countries with Mediterranean climate. Some climate‐ameliorating measures have been developed to control sunburn in apples. Effects of the climate‐ameliorating measures, viz. evaporative cooling, Surround ® WP and shade net, on leaf gas exchange of a 5‐year‐old orchard of ‘Cripps’ Pink’ apple were investigated during hot summer days in Stellenbosch, South Africa. Evaporative cooling increased net photosynthetic rate ( A ) and stomatal conductance ( g s ) because of its lowering of leaf temperature and leaf‐to‐air vapour pressure difference (VPD). Shade net also reduced leaf temperature because of reduction in photosynthetic photon flux density (PPFD). Quantum efficiency of photosynthesis was increased under shade net to compensate for reduced PPFD. Shade net also reduced transpiration rate more than A , resulting in increased midday water‐use efficiency. The diurnal trends of A and g s in the Surround WP and control treatments were similar, indicating limited ameliorative impact of Surround WP. Furthermore, Surround WP typically reduced maximum rate of carboxylation and the light‐saturated rate of electron transport. In all treatments, A decreased by 70% when leaf temperature increased from 35°C to 40°C. In conclusion, all treatments affected leaf photosynthetic gas exchange. Evaporative cooling enhanced leaf A and g s because of distinct ameliorative effects on leaf temperature and VPD. Shade net reduced leaf temperature with no consistent effects on leaf gas exchange attributes. Surround WP had limited or no impact on leaf temperature and negatively affected leaf gas exchange attributes.
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Claims 9
Claim · model-written summary
Evaporative cooling increased photosynthetic rate and stomatal conductance.
- Taxon
- apple
Malus domesticat0 - Organ / stage
- leafe0
- Treatment
- Evaporative coolinge0
- Outcome
- net photosynthetic rate ( A ) and stomatal conductance ( g s )e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“apple leaves”
e0“Evaporative cooling increased net photosynthetic rate ( A ) and stomatal conductance ( g s ) because of its lowering of leaf temperature and leaf‐to‐air vapour pressure difference (VPD).”
Claim · model-written summary
Evaporative cooling lowered leaf temperature and leaf-to-air vapor pressure difference.
- Taxon
- appleMalus domesticat0
- Treatment
- Evaporative coolinge0
- Outcome
- leaf temperature and leaf‐to‐air vapour pressure difference (VPD)e0
- Direction
- loweringe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“apple leaves”
e0“Evaporative cooling increased net photosynthetic rate ( A ) and stomatal conductance ( g s ) because of its lowering of leaf temperature and leaf‐to‐air vapour pressure difference (VPD).”
Claim · model-written summary
Shade net reduced leaf temperature through reduced photon flux density.
- Taxon
- appleMalus domesticat0
- Treatment
- Shade nete0
- Outcome
- leaf temperaturee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“apple leaves”
e0“Shade net also reduced leaf temperature because of reduction in photosynthetic photon flux density (PPFD).”
Claim · model-written summary
Shade net increased quantum efficiency of photosynthesis.
- Taxon
- appleMalus domesticat0
- Treatment
- shade nete0
- Outcome
- Quantum efficiency of photosynthesise0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“apple leaves”
e0“Quantum efficiency of photosynthesis was increased under shade net to compensate for reduced PPFD.”
Claim · model-written summary
Shade net reduced transpiration more than photosynthesis and increased midday water-use efficiency.
- Taxon
- appleMalus domesticat0
- Treatment
- Shade nete0
- Outcome
- transpiration ratee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“apple leaves”
e0“Shade net also reduced transpiration rate more than A , resulting in increased midday water‐use efficiency.”
Claim · model-written summary
Shade net increased midday water-use efficiency.
- Taxon
- appleMalus domesticat0
- Treatment
- Shade nete0
- Outcome
- midday water‐use efficiencye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“apple leaves”
e0“Shade net also reduced transpiration rate more than A , resulting in increased midday water‐use efficiency.”
Claim · model-written summary
Surround WP and control had similar diurnal photosynthesis and conductance trends.
- Taxon
- appleMalus domesticat0
- Treatment
- Surround WPe0
- Outcome
- diurnal trends of A and g se0
- Direction
- similare0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“apple leaves”
e0“The diurnal trends of A and g s in the Surround WP and control treatments were similar”
Claim · model-written summary
Surround WP reduced maximum carboxylation and light-saturated electron transport rates.
- Taxon
- appleMalus domesticat0
- Treatment
- Surround WPe0
- Outcome
- maximum rate of carboxylation and the light‐saturated rate of electron transporte0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“apple leaves”
e0“Surround WP typically reduced maximum rate of carboxylation and the light‐saturated rate of electron transport.”
Claim · model-written summary
Photosynthetic rate declined 70% as leaf temperature rose from 35°C to 40°C.
- Taxon
- appleMalus domesticat0
- Organ / stage
- leafe0
- Outcome
- Ae0
- Direction
- decreasede0
- Value
- 70%e0
- Qualifier
- leaf temperature increased from 35°C to 40°Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“apple leaves”
e0“A decreased by 70% when leaf temperature increased from 35°C to 40°C.”
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See all 8 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.