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Title: POSTHARVEST IMAGING OF CHLOROPHYLL FLUORESCENCE FROM LEMON CAN BE USED TO PREDICT FRUIT QUALITY

Author
item NEDBAL, L - PLANT BIOLOGY UOFI URBANA
item SOUKUPOVA, J - PLANT BIOLOGY UOFI URBANA
item WHITMARSH, CLIFFORD
item TRILEK, M - PLANT BIOLOGY UOFI URBANA

Submitted to: Photosynthetica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Determining postharvest quality is important for lemon growers and producers. We demonstrate the feasibility of assaying and predicting postharvest damage in lemons by monitoring chlorophyll fluorescence. Fruit quality was assayed using a commercial instrument that determines photosynthetic performance by imaging chlorophyll fluorescence parameters. Because photosynthesis is highly sensitive to biotic and abiotic stress, variations in chlorophyll fluorescence parameters over the surface of a lemon fruit can be used to predict areas that will eventually exhibit visible damage. We show that the technique is able to distinguish between mold-infected areas that eventually spread over the surface of the fruit, and damaged areas that do not increase in size during ripening. Our work demonstrates the potential for using rapid imaging of chlorophyll fluorescence in postharvest fruit to develop an automated device that can identify and remove poor quality fruit long before visible damage appears or spreads to other fruit. This study provides the ground work for fruit growers and producers to develop rapid fruit sorting technology.

Technical Abstract: The intensity of chlorophyll fluorescence from photosynthetic tissues provides a non-invasive signal that can be used to determine photosynthetic activity. We show that an imaging kinetic fluorometer can be used to measure chlorophyll fluorescence from non-green plant tissues that have relatively low chlorophyll content. This includes many types of ripening fruit that during development degrade the chloroplasts (including chlorophyll) that are contained in the fruit skin. Even non-green fruit that are highly colored contain active chloroplasts that yield chlorophyll fluorescence signal of sufficient strength that it can be used as a probe photosynthetic activity in the fruit skin. We show that postharvest imaging of chlorophyll fluorescence from lemons can be used to identify regions of the lemon skin that will eventually show visible damage, including infections that can spread from one lemon to another. By comparing fluorescence images with subsequent fruit quality, we identify the fluorescent parameters most robust in predicting surface damage. This study clearly demonstrates chlorophyll fluorescence imaging can identify infected lemons and damaged lemons before visible signs are evident. We propose that chlorophyll fluorescence imaging of lemons can serve as the basis for developing an automated machine that removes damaged or infected fruit long before visible symptoms appear. It is likely this technique can be applied to other ripening fruit.