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Title: ESSENTIAL OILS AND CHILLING INJURY IN LEMON

Author
item Obenland, David - Dave
item Margosan, Dennis
item Houck, Laurie
item Aung, Louis

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The development of acceptable commodity treatments for pest control and quality maintenance is important for the export and marketing of agricultural commodities. Cold treatment is a very safe and effective quarantine treatment for citrus, but its use is hampered by chilling injury to the fruit. We determined if oils in the rind of lemon play a role in causing fruit chilling injury. The rind was severely pitted after 3 weeks or more of storage at 1C. Curing the fruit at 15C for 1 week prior to cold treatment greatly reduced the amount of injury. Chilling-injured fruit released from the rind larger amounts of oils than noninjured fruit. The internal structure of the rind and oil glands did not reveal any abnormal changes as a result of chilling injury. A better understanding of the release of oils from chilling-injured fruit would assist in lessening injury in lemons for export.

Technical Abstract: Essential oils release, localization and concentration in chilling-injured and noninjured lemon (Citrus limon (L.) Burm.) fruit were investigated to enhance understanding of how chilling injury occurs in lemon. Chilling injury in the form of moderate to severe pitting of the flavedo was initially apparent after 3 weeks exposure to 1C, followed by a gradual increase in severity until termination of the experiment after 7 weeks of storage at 1C. Curing the fruit at 15C for 1 week prior to cold treatment greatly reduced the severity of injury. Release from the fruit of d- limonene, a major component of essential oil in lemon, increased with increasing amounts of chilling injury. Studies of the internal anatomy of the flavedo using confocal microscopy indicated that essential oils were present inside of the oil gland and in oil bodies outside of the gland in abundant quantities. Chilling-injured flavedo exhibited no obvious disruption of either the oil glands or the oil bodies. Extraction and quantification of d-limonene from chilling-injured and noninjured flavedo indicated that quite similar amounts of oil were present in the tissue, regardless of injury. Damage to the flavedo after 3 weeks at 1C was noted in the form of flattened or collapsed cells between the top of the gland and the epidermis, whereas collapse of the oil gland only was observed in later stages of injury development.