Effects of chemical thinning, girdling, prunning and potassium treatments on the fruit size of star ruby grapefruit cultivar

In this study, effects of synthetic auxin, girdling, prunning, foliar potassium application and different combinations of these treatments on fruit yiled, fruit size, marketable fruit quantity and fruit quality of 20 years aged Star Ruby grapefruit cultivar which has fruit size issue. The study was conducted at the research and experimental orchard of Cukurova Unversity, Faculty of Agriculture, Department of Horticulture and Star Ruby grapefruit cultivar grafted on sour orange and planted 8 x 8 m was used as plant material.The highest values in terms of fruit yield were determined in Maxim (3,5,6-TPA), Citrimax (2,4-DP) and DG (doube girdling) treatments (605.33, 601.83 and 589 kg, respectively). In terms of the amount of marketable fruit, regarded as the most important factor directly related to both producers and exporters, hand prunning (221.65 kg), Maxim (205.81 kg) and foliar potassium application (190.74 kg) were the most prominent treatments. The lowest amount of marketable fruit was determined in control treatment.Keywords: Star Ruby, 3,5,6-TPA, 2,4-DP, Potassium, Girdling