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Changes in Respiration and Ethylene Evolution Induced by Diplodia natalensis in Orange Fruit. G. Zauberman, Division of Fruit & Vegetable Storage, Institute for Technology and Storage of Agricultural Products, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50200, Israel; Rivka Barkai-Golan, Division of Fruit & Vegetable Storage, Institute for Technology and Storage of Agricultural Products, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50200, Israel. Phytopathology 65:216-217. DOI: 10.1094/Phyto-65-216.

The respiratory rate and ethylene evolution of “Valencia” oranges were higher in fruit infected with Diplodia natalensis than in uninfected fruit during 10 days at 23 C. Acceleration of both physiological processes was first detected 5 days after inoculation, coinciding with the initial appearance of disease symptoms at the stem-end of the fruit. The rates continued to rise rapidly as the disease progressed. Maximal values were reached on the 8th day after inoculation, when a sharp drop ensued. Fruit rotting, however, continued until total rotting occurred. In uninfected fruits - whether wounded or unwounded - both respiration and ethylene rates were low and remained constant for 10 days.