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Title: IMPORTANCE OF POSTHARVEST EVALUATION IN A FRESH FRUIT BREEDING PROGRAM: USDA 77-19 A CASE IN POINT

Author
item McCollum, Thomas
item Chaparro, Jose

Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Proceedings
Publication Acceptance Date: 6/16/2004
Publication Date: 7/1/2004
Citation: Mccollum,T.G.,Chaparro,J.X.2004.Importance of postharvest evaluation in a fresh fruit breeding program: usda 77-19 a case in point. Proceedings of Florida State Horticultural Society.

Interpretive Summary: One objective of the USDA citrus scion breeding program is to develop new citrus fruit types to ensure the competitiveness of the US citrus industry. USDA 77-19 is a promising new grapefruit-like hybrid that has the advantages of being early maturing, non-bitter and low in acid. The fruit have been well received in consumer taste tests. In order to be marketable the fruit must be able to withstand the rigors of postharvest handling so that they reach the consumer in good condition. We conducted a series of experiments to determine how USDA 77-19 fruit would perform following harvest. We found that USDA 77-19 fruit are prone to developing rind disorders that could affect their marketability. These findings must be taken into account when considering whether or not to release the variety to the public and if released, provide recommendations as to the market potential of the fruit.

Technical Abstract: Development of new citrus fruit cultivars for the fresh market is recognized as essential for the US citrus industry to remain competitive. The breeding selection USDA 77-19 is a new grapefruit-like hybrid developed by the USDA citrus breeding program. The original hybrid, USDA 75-8 was selected in 1973 from a population of 'Pearl' tangelo x grapefruit hybrids. Budwood of USDA 75-8 was irradiated in 1980 to generate seedless mutants and USDA 77-19 was a low seed content selection made from the irradiated material. Fruit of USDA 77-19 are non-bitter and reach commercial maturity in early September. USDA 77-19 has the potential to fill a niche for an early-ripening low acid non-bitter grapefruit. The fruit have been evaluated in taste tests and have good consumer acceptance. In an effort to determine the market potential for USDA 77-19, we conducted trials to determine the postharvest performance of fruit. We found that USDA 77-19 fruit were highly susceptible to stem end rot, and that the disease was aggravated by exposing the fruit to ethylene. Fungicide treatment reduced the amount of stem end rot, but not to acceptable levels. In addition, in one trial we observed that USDA 77-19 fruit were highly susceptible to chilling injury. Such postharvest problems suggest that USDA 77-19 may only be suitable for local marketing. Results of this work demonstrate the crucial importance of postharvest trials in the development of new fresh market citrus fruit cultivars to ensure the marketability of the fruit.