STUDIES ON RIPENING PATTERN OF SEABUCKTHORN (HIPPOPHAE) FRUITS
Zhang Wei, Li Chengyi, Liu Dong, Deng Xuezhen, Zhang Hui ( Institute of Biology, Gansu Academy, Lanzhon ) Du Changyou, Li Youjun ( Tianzhu Bureau of Forestry, Gansu )
The phenological stages of seabuckthorn ( Hippophae rhamnoides L. subsp. sinensis rousi and H. thibetana Schlechted ) distributed natura-lly over an area of Wushao ridge were observed.The respiratory rate, and the changes in the levels of endogenous phytphormones-IAA, ABA and ethylene were investigated during the developing and ripening periods of these two species of fruits. The results showed that both the respiratory rate and IAA levels were very high during the early stages of fruit growth, decreased to a minimum at color changing phase and just at this time, ABA first appeared. ABA reached a maximum in the last ten days of Sep. ( 135 139 days after anthesis ) during full ripening stage of fruits.After the full ripening stage, IAA levels increased once more both in the flesh and in the seeds. An increase in respiratory rate apeared at the earlier last ten days of Sep. (133 days after anthesis) in Hippophae sinensis and at the first ten days of Sep. ( 115 days after anthesis) in H. thibetana when the seeds reached the full ripening phase. But only trace of ethylene was detected in the ripening stages. Based on the above facts, it is reasonable to consider that it is ABA which plays an importent regulating role in the changes of developing stages and ripening process of seabuckthorn fruits. According to its ripening pattern, the seabuckthorn fruits seems to belong to the nonclimacteric fruits, but with an increase in respiratory rate during the ripening period, which is different from other nonclimacteric fruits.