Abstract
SummaryHigh-value fruit crops are exposed to a range of environmental conditions that can reduce fruit quality. Solar injury (SI) or sunburn is a common disorder in tropical, sub-tropical, and temperate climates and is related to: 1) high fruit surface temperature; 2) high visible light intensity; and, 3) ultraviolet radiation (UV). Positional changes in fruit that are caused by increased weight or abrupt changes that result from Summer pruning, limb breakage, or other damage to the canopy can expose fruit to high solar radiation levels, increased fruit surface temperatures, and increased UV exposure that are higher than the conditions to which they are adapted. In our studies, we examined the effects of high fruit surface temperature, saturating photosynthetically-active radiation (PAR), and short-term UV exposure on chlorophyll fluorescence, respiration, and photosynthesis of fruit peel tissues from tropical and temperate fruit in a simulation of these acute environmental changes. All tropical fruits (citrus, macadamia, avocado, pineapple, and custard apple) and the apple cultivars ‘Gala’, ‘Gold Rush’, and ‘Granny Smith’ increased dark respiration (A0) when exposed to UV, suggesting that UV repair mechanisms were induced. The maximum quantum efficiency of photosystem II (Fv/Fm) and the quantum efficiency of photosystem II ( II) were unaffected, indicating no adverse effects on photosystem II (PSII). In contrast, ‘Braeburn’ apple had a reduced Fv/Fm with no increase in A0 on all sampling dates.There was a consistent pattern in all studies.When Fv/Fm was unaffected by UV treatment, A0 increased significantly. Conversely, when Fv/Fm was reduced by UV treatment, then A0 was unaffected. The pattern suggests that when UV repair mechanisms are effective, PSII is adequately protected, and that this protection occurs at the cost of higher respiration. However, when the UV repair mechanisms are ineffective, not only is PSII damaged, but there is additional short-term damage to the repair mechanisms, indicated by a lack of respiration to provide energy.
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Claims 9
Claim · model-written summary
UV increased dark respiration in the five named tropical fruit crops.
- Material
- citrus, macadamia, avocado, pineapple, and custard applee0
- Treatment
- UVe0
- Outcome
- dark respiration (A0)e0
- Direction
- increasede0
CitrusNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All tropical fruits (citrus, macadamia, avocado, pineapple, and custard apple) and the apple cultivars ‘Gala’, ‘Gold Rush’, and ‘Granny Smith’ increased dark respiration (A0) when exposed to UV”
Claim · model-written summary
UV increased dark respiration in Gala, Gold Rush and Granny Smith apple cultivars.
- Taxon
- apple
Malus domesticae0 - Material
- ‘Gala’, ‘Gold Rush’, and ‘Granny Smith’e0
- Treatment
- UVe0
- Outcome
- dark respiration (A0)e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the apple cultivars ‘Gala’, ‘Gold Rush’, and ‘Granny Smith’ increased dark respiration (A0) when exposed to UV”
Claim · model-written summary
Photosystem II quantum efficiencies were unaffected by UV in the fruit studies.
- Taxon
- appleMalus domesticae1
- Treatment
- UVe1
- Outcome
- maximum quantum efficiency of photosystem II (Fv/Fm) and the quantum efficiency of photosystem II ( II)e0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The maximum quantum efficiency of photosystem II (Fv/Fm) and the quantum efficiency of photosystem II ( II) were unaffected”
e1“All tropical fruits (citrus, macadamia, avocado, pineapple, and custard apple) and the apple cultivars ‘Gala’, ‘Gold Rush’, and ‘Granny Smith’ increased dark respiration (A0) when exposed to UV”
Claim · model-written summary
Braeburn apple had reduced Fv/Fm under UV.
- Taxon
- appleMalus domesticae0
- Material
- ‘Braeburn’e0
- Outcome
- Fv/Fme0
- Direction
- reducede0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“‘Braeburn’ apple had a reduced Fv/Fm with no increase in A0”
Claim · model-written summary
Braeburn apple had no increase in dark respiration under UV.
- Taxon
- appleMalus domesticae0
- Material
- ‘Braeburn’e0
- Outcome
- A0e0
- Direction
- no increasee0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“‘Braeburn’ apple had a reduced Fv/Fm with no increase in A0”
Claim · model-written summary
Across studies, unaffected Fv/Fm accompanied significantly increased dark respiration.
- Taxon
- appleMalus domesticae1
- Treatment
- UV treatmente0
- Outcome
- A0e0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When Fv/Fm was unaffected by UV treatment, A0 increased significantly.”
e1“the apple cultivars ‘Gala’, ‘Gold Rush’, and ‘Granny Smith’”
Claim · model-written summary
Across studies, reduced Fv/Fm accompanied unaffected dark respiration.
- Taxon
- appleMalus domesticae1
- Treatment
- UV treatmente0
- Outcome
- A0e0
- Direction
- unaffectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when Fv/Fm was reduced by UV treatment, then A0 was unaffected.”
e1“the apple cultivars ‘Gala’, ‘Gold Rush’, and ‘Granny Smith’”
Claim · model-written summary
The authors infer effective UV repair protects PSII at the cost of increased respiration.
- Taxon
- appleMalus domesticae1
- Outcome
- PSII is adequately protectede0
- Direction
- highere0
- Qualifier
- UV repair mechanisms are effectivee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when UV repair mechanisms are effective, PSII is adequately protected, and that this protection occurs at the cost of higher respiration”
e1“the apple cultivars ‘Gala’, ‘Gold Rush’, and ‘Granny Smith’”
Claim · model-written summary
The authors infer ineffective UV repair coincides with PSII damage and short-term repair damage.
- Taxon
- appleMalus domesticae1
- Outcome
- PSII damagede0
- Qualifier
- UV repair mechanisms are ineffectivee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when the UV repair mechanisms are ineffective, not only is PSII damaged, but there is additional short-term damage to the repair mechanisms, indicated by a lack of respiration to provide energy”
e1“the apple cultivars ‘Gala’, ‘Gold Rush’, and ‘Granny Smith’”
The same questions in other papers
radiation · physiology: respiration · CitrusPositive and negative results
1 in the opposite direction
- negative
radiation · physiology: respiration · Malus domestica (apple)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- negative
- positive
uv · physiology: photosynthesis · Malus domestica (apple)Results agree
2 papers in the same direction as this paper
- negative
- no effect
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.