Producing seedless fruits of watermelon by hormonal agents is a parthenocarpic phenomenon in which fertilization is not needed for growth. In order for parthenocarpically developed watermelon to reach normal size, pollination and pseudogamy are necessary. Generally, after pollination, growth of the ovary is induced by auxin derived from pollen grain and by auxin induced by stimulation from the pollen tube in the pistil. Further ovary development is promoted by auxin derived from the developing embryo after fertilization (Saitou, 1974). However, a watermelon fruit which is produced only by hormonal treatment is smaller than that produced by pollination