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United States Department of Agriculture

Agricultural Research Service

Title: Ultraviolet radiation effects on fruit surface respiration and chlorophyll fluorescence

Authors
item Glenn, D Michael
item Wunsche, J. - HAWKS BAY RES CTR, NZ
item Mcivor, I. - HORT RESEARCH, NZ
item Nissen, Robert - DEPT PRIM IND&FISH, AUSTR
item George, Alan - DEPT PRIM IND&FISH, AUSTR

Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 16, 2007
Publication Date: January 1, 2008
Citation: Glenn, D.M., Wunsche, J., Mcivor, I., Nissen, R., George, A. 2008. Ultraviolet radiation effects on fruit surface respiration and chlorophyll fluorescence. Journal of Horticultural Science and Biotechnology. 83(1):43-50.

Interpretive Summary: Solar injury (SI) or sunburn is a common disorder in tropical, subtropical and temperate climates and is related to: 1) high fruit surface temperature, 2) high visible light intensity, 3) ultraviolet radiation (UV) and 4) positional changes in fruit that expose fruit to high solar radiation levels to which they are not adapted. In this work, we examined the interaction of high fruit surface temperature, high light intensity and short term UV exposure on respiration, and photosynthesis of fruit peel tissues from tropical and temperate fruit as a simulation of these positional changes. All tropical fruit (citrus, macadamia, avocado, pineapple and custard apple) and the apple cultivars: 'Gala', 'Gold Rush', and 'Granny Smith', increased respiration when challenged with UV suggesting that UV repair mechanisms are induced and require more energy in the form of respiration. The efficiency of photosynthesis was unaffected by the UV treatments indicating no adverse effects the building blocks of photosynthesis. In contrast, 'Braeburn' apple had reduced photosynthetic efficiency with no increase in respiration at all sampling dates. The pattern suggests that when UV repair mechanisms are effective, photosynthetic efficiency is adequately protected and the protection occurs at the cost of higher respiration. These results provide new information on the mechanisms of SI and can be used to evaluate the SI resistance of new cultivars in a range of species.

Technical Abstract: High-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, subtropical 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 due to increased weight or abrupt changes due to summer pruning, limb breakage or other damage to the canopy can expose fruit to high solar radiation levels, increased fruit surface temperature and increased UV exposure that are higher than the conditions to which they are adapted. In this work, we examined the interaction 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 as a simulation of these acute environmental changes. All tropical fruit (citrus, macadamia, avocado, pineapple and custard apple) and the apple cultivars: 'Gala', 'Gold Rush', and 'Granny Smith', increased dark respiration, Ao, when challenged with UV suggesting that UV repair mechanisms are induced. Maximum quantum efficiency of photosystem II ( FvFm ) and quantum efficiency of photosystem II ( Psi II ) were unaffected indicating no adverse effects on photosystem II (PSII). In contrast, 'Braeburn' apple had reduced Fv/Fm with no increase in Ao at all sampling dates. There was a consistent pattern in all studies: when Fv/Fm was unaffected by the UV treatment, Ao was significantly increased. Conversely, when Fv/Fm was reduced by the UV treatment, then Ao was unaffected. The pattern suggests that when UV repair mechanisms are effective, PSII is adequately protected and the 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.

Last Modified: 4/18/2014
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