Yildirim, B.Yesiloglu, T.Incesu, M.Kamiloglu, M. U.Cimen, B.Tamer, S.2024-09-182024-09-1820120114-06711175-8783https://doi.org/10.1080/01140671.2011.604091https://hdl.handle.net/20.500.12483/8032The Valencia orange is a high-quality fruit grown in Turkey; however, small fruit sizes and high fruit discard percentages are common in Valencia oranges. Small fruit size is the main factor limiting the marketing of Valencia oranges; thus, synthetic auxins are commonly used to enhance the size of citrus fruit. The objective of the present study was to observe the effects of 2,4-dichlorophenoxypropionic acid (2,4-DP) on the fruit size, yield and quality of Valencia oranges from 29-year-old trees budded on sour orange rootstock in Adana, Turkey during 2005-06. Three concentrations (50, 100 and 150 ppm) of 2,4-DP were applied during the June drop, when the mean fruit diameter was 13-15 mm. The results indicated that the application of 2,4-DP increased the fruit size of Valencia oranges without reducing yield. The application had a significant effect on fruit yield. Compared with the control trees, applications of 2,4-DP increased the number of large, commercially valuable Valencia oranges (75-80 mm). Moreover, an increase in the concentration of 2,4-DP increased the yield and weight of the fruits. As a result, fruit retention was highest in trees sprayed with 150 ppm 2,4-DP. Except for the titratable acid content (TA), which increased with an increase in the 2,4-DP concentration, the internal characteristics of the fruit were not affected by treatment with 2,4-DP. Thus, the results of the present study revealed that 2,4-DP can be used to improve the fruit size of Valencia fruitlets during the June drop.eninfo:eu-repo/semantics/openAccessauxinfruit qualityValencia orangeyieldplant growth regulatorsArticle401556410.1080/01140671.2011.6040912-s2.0-84862842739Q2WOS:000304592500006Q3