Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2005
Publication Date: 10/1/2005
Citation: Obenland, D.M., Neipp, P.W. 2005. Chlorophyll fluorescence imaging allows early detection and localization of lemon rind injury following hot water treatment. Hortscience 40(6):1821-1823. Interpretive Summary: Citrus often suffer rind injury as a result of non-chemical alternative treatments to methyl bromide fumigation but study of the basis of the injury is hampered by an inability to determine areas of the rind that are damaged early in the development of the injury. Measurement of chlorophyll fluorescence immediately following hot water treatment of lemons was found to provide a rapid and effective means of determining where treatment-induced injury will occur following storage. This method may be useful in determining the biochemical basis of rind injury and facilitate the development of alternative treatments to methyl bromide.
Technical Abstract: Green lemons (Citrus limon (L.) Burm.) were imaged for chlorophyll fluorescence (CF) 30 min after immersion of the fruit into 55 °C water for 5 min to determine if CF could be used to identify areas of hot water-induced rind injury prior to the appearance of visible symptoms. Fluorescence was variable in intensity over the surface of the rind with defined areas of enhanced fluorescence being present that corresponded in shape and location with visible injury that later developed during 24 h of storage. Images showing minimum fluorescence (F0) and maximal fluorescence (Fm) provided the best image contrast between injured and non-injured areas of the rind. Total F0 present in the image was closely correlated (r = 0.87) with the area of rind injury present following storage. Holding the fruit under conditions of low humidity for 24 h prior to hot water treatment prevented both the formation of areas of enhanced fluorescence and the corresponding rind injury. Imaging of CF has potential as a means to identify areas of incipient rind injury in citrus in order to facilitate study of the causal mechanisms of postharvest rind disorders.