RESEARCH ON SEED CHARACTERISTICS AND PROPAGATION TECHNIQUES OF Cupressus tonkinensis Silba. J.

Abstract

Cupressus tonkinensis Silba. J. is one of the 10 pine species prioritized for conservation activities in Vietnam. This is a narrow endemic and rare plant species, classified as Critically Endangered (CR A1a, d) in the Vietnam Red Book of 2007 and listed in Group IA (List of Endangered, Rare, and Precious Forest Plants and Animals) under Decree 84/2021/NĐ-CP dated September 22, 2021, of the Government. The research seeds were harvested from scattered cultivated trees at three locations: Xuan Mai (Ha Noi), Phuc Yen (Vinh Phuc) and Huu Lien (Lang Son). The results determined that the purity of the Cupressus tonkinensis seedlots ranged from 93.41 to 95.49%. The average weight of 1,000 seeds varied from 6.89 - 7.06 g, corresponding to approximately 140,000 - 145,000 seeds per kilogram. The average germination rate was 43.3%, with an average germination speed of about 17.1 days and an average germination capacity of 22.7%. Soaking the seeds in warm water at 45 °C for 8 hours yielded the highest germination rate, also reaching 43.3%. When seeds were stored at 5 - 8 °C, the germination rate was 34% after 6 months of storage. The optimal potting mix for the seedlings consisted of 90% surface soil from under the forest canopy and 10% organic fertilizer, with 50% shade providing the best seedling growth.