关键词: 小兴安岭, 森林沼泽, 非生长季, 采伐干扰, 温室气体

Abstract: The process of seed germination ofGarcinia paucinervis, a rare and endangered plant, is extremely long. Clarifying its dormancy mechanism would provide a theoretical basis for germplasm conservation and sustainable utilization of this species. In this study, we examined the seed coat structure and water absorption characters, the germination of seeds removed part of seed coats and endosperm, the activities of crude extract of endosperm and embryos, seed germination after storage or stratification and under different temperature treatments as well as contents ofendogenous phytohormone during germination. The results showed that the seed coat ofG. paucinervis was mainly composed of parenchymatous layer without palisade layer. The cuticle of abaxial surface was thin. The seed coat had little inhibition to water absorption. With the extent of the elimination of seed coats and endosperm at the side of micropyle, seed germination gradually extended and its germination percentage was even reduced. The treatment of cutting off at the side of hilum had limited effects on seed germination. Endogenous inhibitors for seed germination would exist in endocarp, seed coats, endosperms, and embryos. The embryo rate of fresh seeds reached 86.12%, and showed no significant change after cold stratification. Cold stratificationdelayed seed germination but had no significant effect on germination percentage. Stratification at 4 ℃ was a better method for seed storage of G. paucinervis. Seed germination was sensitive to the changes of temperature. Seed dormancy was broken at 32 ℃, and then the germination was significantly accelerated. During the seed germination, ABA (abscisic acid) content decreased, whereas the ratios of GA (gibberellin) to IAA (indole-3-acetic acid) and GA to ABA significantly increased. The ratios of endogenous accelerants to inhibitors were gradually partial to acceleration. Our results indicated thatG. paucinervis seeds belong to physiological dormancy caused by existence of endogenous inhibitors and lack of germination accelerants. The dormancy characteristics of G. paucinervis seeds would facilitate the responses of seedlings to the seasonal changes of habitats, favor population survive under stress environment, and avoid seedling competition. The barrier of seed germination stage caused by vegetation destruction was one of the reasons for theendangerment ofG. paucinervis.

Key words: greenhouse gas, forested swamp, non-growing season, harvesting., Xiaoxing’an Mountains