Abstract
The dark green apple cultivar, Granny Smith (GS), makes up 25% of the South African apple industry. However, production of GS is becoming unprofitable as a result of a high incidence of sunburn, red blush, and pale green fruit that decreases the proportion of Class 1 fruit that is suitable for export to more lucrative markets. This study was conducted to investigate the relationship between canopy position and external fruit quality with the ultimate aim to devise pruning and training strategies to maximize export yield. During early fruit development [26 days after full bloom (DAFB)], chlorophyll concentrations were the highest in fruit from higher light environments. Good green color at harvest relied on exposure of fruit to high irradiance at this stage because 50% shading between 14 and 56 DAFB significantly decreased dark green color at harvest. Exposed fruit from the northern side of east–west rows received the highest irradiance throughout the season [53% of full sun photosynthetic photon flux ( PPF )] and had the highest fruit surface temperature (on average 5 °C above ambient). A high proportion of exposed fruit from either side of the row developed red blush. Only 22% to 39% of exposed fruit from the outer canopy did not develop sunburn or red blush. Partially shaded fruit from the southern side of east–west rows received ≈5% of full sunlight and had the highest chlorophyll concentrations and darkest green color at harvest. Deeply shaded inner canopy fruit received ≈2% of full sunlight, had low chlorophyll concentrations, and were lighter green in color. The 10% darkest green fruit received moderately high irradiance (25% to 45% of full sun PPF ) during early fruit development (until ≈80 DAFB) but became progressively shaded (3% of full sun PPF ) during the latter half of the season. Fruit that developed sunburn and the lightest green fruit were exposed to high (1300 μmol·m −2 ·s −1 ) and extremely low (50 μmol·m −2 ·s −1 ) light, respectively, throughout their development. In conclusion, maximum chlorophyll synthesis and dark green color require an open canopy during the first half of fruit development, whereas shading is necessary during the latter half of fruit development to avoid the occurrence of sunburn, red blush, and photothermal destruction of chlorophyll. GS may benefit significantly from the installation of shade netting if combined with rigorous pruning and vigor control.
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Claims 13
Claim · model-written summary
Early fruit in higher light had the highest chlorophyll concentrations.
- Taxon
- apple
Malus domesticat0 - Outcome
- chlorophyll concentrationse0
- Direction
- higheste0
- Setting
- higher light environmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“chlorophyll concentrations were the highest in fruit from higher light environments”
t0“Apples”
Claim · model-written summary
Shading between 14 and 56 DAFB decreased dark green color at harvest.
- Taxon
- appleMalus domesticat0
- Treatment
- 50% shading between 14 and 56 DAFBe0
- Outcome
- dark green colore0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“50% shading between 14 and 56 DAFB significantly decreased dark green color at harvest”
t0“Apples”
Claim · model-written summary
Northern exposed fruit received 53% of full sun PPF.
- Taxon
- appleMalus domesticat0
- Outcome
- irradiancee0
- Direction
- higheste0
- Value
- 53% of full sun photosynthetic photon fluxe0
- Setting
- northern side of east–west rowse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exposed fruit from the northern side of east–west rows received the highest irradiance throughout the season [53% of full sun photosynthetic photon flux ( PPF )]”
t0“Apples”
Claim · model-written summary
Northern exposed fruit surface temperature averaged 5 °C above ambient.
- Taxon
- appleMalus domesticat0
- Outcome
- fruit surface temperaturee0
- Direction
- higheste0
- Value
- 5 °C above ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“had the highest fruit surface temperature (on average 5 °C above ambient)”
t0“Apples”
Claim · model-written summary
A high proportion of exposed fruit developed red blush.
- Taxon
- appleMalus domesticat0
- Outcome
- red blushe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A high proportion of exposed fruit from either side of the row developed red blush”
t0“Apples”
Claim · model-written summary
Only 22% to 39% of exposed outer canopy fruit avoided both sunburn and red blush.
- Taxon
- appleMalus domesticat0
- Outcome
- did not develop sunburn or red blushe0
- Value
- 22% to 39%e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Only 22% to 39% of exposed fruit from the outer canopy did not develop sunburn or red blush”
t0“Apples”
Claim · model-written summary
Partially shaded southern fruit had the highest chlorophyll concentration and darkest green color.
- Taxon
- appleMalus domesticat0
- Outcome
- highest chlorophyll concentrations and darkest green colore0
- Direction
- higheste0
- Value
- ≈5% of full sunlighte0
- Setting
- southern side of east–west rowse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Partially shaded fruit from the southern side of east–west rows received ≈5% of full sunlight and had the highest chlorophyll concentrations and darkest green color at harvest”
t0“Apples”
Claim · model-written summary
Deeply shaded inner fruit had low chlorophyll and lighter green color.
- Taxon
- appleMalus domesticat0
- Outcome
- low chlorophyll concentrations, and were lighter green in colore0
- Direction
- lowe0
- Value
- ≈2% of full sunlighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Deeply shaded inner canopy fruit received ≈2% of full sunlight, had low chlorophyll concentrations, and were lighter green in color”
t0“Apples”
Claim · model-written summary
The darkest green fruit experienced moderate early irradiance and later shading.
- Taxon
- appleMalus domesticat0
- Outcome
- darkest green fruite0
- Qualifier
- progressively shadede0
- Setting
- moderately high irradiancee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The 10% darkest green fruit received moderately high irradiance (25% to 45% of full sun PPF ) during early fruit development (until ≈80 DAFB) but became progressively shaded (3% of full sun PPF ) during the latter half of the season”
t0“Apples”
Claim · model-written summary
Sunburn fruit was exposed to high light throughout development.
- Taxon
- appleMalus domesticat0
- Outcome
- developed sunburne0
- Value
- 1300 μmol·m −2 ·s −1e0
- Setting
- highe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fruit that developed sunburn and the lightest green fruit were exposed to high (1300 μmol·m −2 ·s −1 ) and extremely low (50 μmol·m −2 ·s −1 ) light, respectively, throughout their development”
t0“Apples”
Claim · model-written summary
The lightest green fruit was exposed to extremely low light throughout development.
- Taxon
- appleMalus domesticat0
- Outcome
- lightest green fruite0
- Direction
- lighteste0
- Value
- 50 μmol·m −2 ·s −1e0
- Setting
- extremely lowe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fruit that developed sunburn and the lightest green fruit were exposed to high (1300 μmol·m −2 ·s −1 ) and extremely low (50 μmol·m −2 ·s −1 ) light, respectively, throughout their development”
t0“Apples”
Claim · model-written summary
The authors recommend early open canopy followed by late shading for green color and blemish avoidance.
- Taxon
- appleMalus domesticat0
- Outcome
- an open canopy during the first half of fruit developmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maximum chlorophyll synthesis and dark green color require an open canopy during the first half of fruit development, whereas shading is necessary during the latter half of fruit development to avoid the occurrence of sunburn, red blush, and photothermal destruction of chlorophyll”
t0“Apples”
Claim · model-written summary
The authors suggest shade netting combined with pruning and vigor control.
- Taxon
- appleMalus domesticat0
- Outcome
- installation of shade nettinge0
- Qualifier
- if combined with rigorous pruning and vigor controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GS may benefit significantly from the installation of shade netting if combined with rigorous pruning and vigor control”
t0“Apples”
The same questions in other papers
shade · quality: postharvest · Malus domestica (apple)Positive and negative results
5 papers in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- negative
4 papers more in this group
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.