THE DORMANCY TYPES AND CHARACTERISTICS OF THE SEEDS OF MEDICINAL PLANTS

According to our experiments with seeds of 80 species of medicinal plants, andrefering to the published literature, the dormancy of seeds of medicinal plants can be divided into three types:Ⅰ. Impermeability of the seed coats to water or gases: Seeds of Eucommia ulmoides, Polygonum bistorta, P. cuspidatum, Astragalus membranaceus, Pharbitis hederacea, Erodium stephakianum, Rhus chinensis, Caesalpinia sepiaria bear hard coats and thus limit germination.Ⅱ. Seeds with immature Embryos:(1) High-low temperature type: seeds of Panax ginseng, P. quinguefolius, P. major, Acanthopanax senticosus, A. gracilistylus, Corydalis repens, Notopterygium forbesii Euphorbia fischeriana belong to this type.(2) Low temperature type: lots of seeds, such as Aconitum carmichaeli, A. kusnezoffii, Berberis amurensis, B. poiretii, Carduus crispus, Chaenomeles lagenaria, C. sinensis, Cocculus trilobus, Codonopsis lanceolata, Coptis chinensis, Cyperus rotundus, Dioscorea nipponica, Eucommia ulmoides, Euonymus alatus, Fritillaria pallidiflora, Gentiana mamshurica, G. scabra, G. triflora, Clehnia littoralis, Lithospermum erythrorrhizon, Menispermum dahuricum, Phellodendron amurense, Physochlaina physalioides, Schisandra chinensis, S. sphenanthera, Stephania tetrandra, Trollius chinensis are of this type.(3) Epicotyl dormancy: epicotyl dormancy has been shown to be characteristic of seeds of Asarum heterotropoides vat. mandshuricum, Asparagus cochinchinensis, Paeonia lactiflora, P. suffruticosa, Paris polyphylla, Polygonatum odoratum, Smilax china, Viburnum dilatatum.(4) Two-year seeds: seeds need two periods of low temperature to break the dormancy. For example, the seeds of Colchicum autumnale, Leontice robustum, Trillium grandiflorum etc germinate after two winters.(5) Metabolic barrier of embryo(hormonal regulation): dormancy is due to the inability of embryo to use reserved food within the endosperm and is regulated by hormones. In our experiments gibberellin promotes germination of Gentiana manshurica, Trollius chinensis, Zanthoxylum bungeanum.Ⅲ. Seeds possessing both impermeable seed coats and dormancy embryos: seeds of Cornus officinalis, Crataegus pinnatifida, Aralia chinensis, Cephalotaxus sinensis, Zizyphus jujuba vat. spinosus are of this type.