Lack of compliance with the production standards demanded by importing countries is the primary factor limiting the exportability of the citrus fruits. This study proposes that there is a need for a new, horizontally integrated management model for improving the competitiveness of the Turkish citrus sector in the global markets. This study focuses on the citrus exporting firms of Mersin province, which was selected to represent the Eastern Mediterranean region of Turkey. During the face-to-face interviews done with the firms’ representatives, a semi-structured questionnaire form was used. The data were collected through in-depth interview technique. Potential benefits of the proposed regional processing center in a vertically-integrated supply chain were tested through models constructed with the Simio Modeling Software. The models compared how well twenty hypothetical firms with identical sizes filled the orders they received with different purchasing policies: In Model-1, the firms tried to meet the orders independently, from the stocks of the fruits which they randomly purchased. In Model-2, the firms tried to meet the orders independently, through planned purchases made only for the amounts demanded in the orders. In Model-3, the firms tried to meet the orders through a regional processing center which purchased the fruits randomly. The results have shown that, independently operating firms would fill orders more efficiently by making planned purchases, for the amounts demanded in the orders, but purchasing processed fruits from a regional center would shorten the delivery time and/or reduce the unused stocks.