Yield and fruit quality of two late-maturing Valencia orange tree varieties as affected by harvest date

Introduction. Since citrus fruits are non-climacteric, commercial harvest for a given variety can occur over a prolonged period in the same orchard. Delayed citrus harvest has previously been reported to influence fruit quality variables during the current season and to reduce the subsequent year's yield. The aim of our study was to investigate the effect of harvest date on tree yield and fruit quality of two late-maturing Valencia orange varieties during two successive years. Materials and methods. One hundred 9-year-old Campbell and Lue Gim Gong Valencia orange trees budded on Swingle citrumelo rootstock were used. Fruit sampling included fruit harvest at five monthly intervals (April-August) during 2003, and only one harvest date ( 20 June) during 2004. Results and discussion. Based on seasonal variation of various fruit quality variables during the five harvests conducted in 2003, the most stable fruit quality variables were fruit weight, number of seeds per fruit, rind thickness, juice content and soluble solids content. In general, both varieties produced fruit with similar internal quality characteristics. However, their mean fruit weight differed in 2004 ( Lue Gim Gong had larger fruit than Campbell). Furthermore, the annual and cumulative yields of Lue Gim Gong Valencia orange trees over two years were significantly higher than those of Campbell orange trees. Finally, the yield per tree and fruit quality of both varieties in 2003 and 2004 were not affected significantly by the date of harvest during 2003.