Juice Vesicle Populations in Citrus Fruit

The total number of vesicles within the fruits of several species of the Aurantioideae (Rutaceae) was determined. Two distinct vesicle shape types are recognized: superior and inferior. There was a significant correlation with the number of juice vesicles per fruit and the number of segments found within the fruit. Citrus species (e.g., grapefruit and pummelo) containing fruit composed of many segments (e.g., 10-14 and 20, respectively) correspondingly contained more vesicles per segment than those citrus species (e.g., kumquat and mandarin) containing fruit with few segments (4 and 7-10, respectively). Significant correlations were found between vesicle number and segment area or segment weight. Large segments weighed more and contained more vesicles than small segments. Seed number per fruit or per segment did not have significant correlation with the number of vesicles produced per fruit or per segment. A formula, based upon a partial fruit analysis, to estimate the total number of vesicles in a fruit within 5% of the actual number is presented. The number of vesicles produced in fruit was found to be influenced by environment. Fruit from trees of `Eureka' lemon and `Improved' Meyer lemons grown inside a temperature controlled greenhouse contained more vesicles than fruit from trees grown outdoors.