Physicochemical Characteristics of Kumquat (Fortunella margarita) on Citrus Rootstocks

The aim of this study was to determine organic acids and individual sugars as well as carotenoids in fruit of Kumquat[Fortunella margarita (Lour.) Swingle] on different rootstocks.  On other hand, the purpose of this study was to identify the rootstock that could produce the highest amount of sugars. The content of individual sugars and organic acids in fruits were determined by HPLC, whereas spectrophotometer was used to determine the total carotenoids and chlorophylls. Total acidity (TA), total soluble solids (TSS) and pH value of juice was also evaluated. The content of ethylene in fruits was determined by Gas chromatograph. The results showed that, the highest of total sugars (51.63 mg/mL), pH (2.43), TSS (11.06%) and TSS/TA (3.71) were in fruit of Kumquat(Fortunella Margarita) grafting on the Troyer citrange rootstock. According to results, the amount of citric acid (45.07 mg/mL), ascorbic acid (0.41 mg/mL), juice (26.78 (%) and carotenoids (0.10 mg/gr DW) of Kumquat grafted on Sour orange was higher than those of other rootstocks. Among the sugars, Sucrose was determined in the highest concentration in all investigated fruits. The results of correlation showed that there were a high positive correlation between the amount of sucrose and glucose. Results showed that Troyer citrange rootstock had an important role in increasing of sugars, pH, TSS, as well as TSS/TA. Finally based on the obtained results it can be concluded that although the concentration of sugars and organic acids is strongly related to the genotype of fruit, it seems that rootstocks affect the amount of sugars and organic acids.