Germination phenoology and mechanism of seed dormancy on northern landscaping plants that need two years from seed dispersal to germination

在日本北部，有几种美观的乡土植物，其中一些植物的种子从种子散布到子叶出苗需要两个冬天。本研究旨在揭示这类种子的萌发生理生态和种子休眠机制。当种子散布时，甘蓝具有不发达的胚胎。种子散布到胚根萌发历时18mo，子叶自然萌发历时19mo，具有较深的形态生理休眠。而25/15℃(60d)→15/5℃(30d)→0℃(120d)→15/5℃的培养温度可将播种至辐射出苗的时间缩短至7~8mo。秋季采收，5℃贮藏，次年6月播种，次年春季发芽率达88%以上。另一方面，在第二年8月播种的种子或更晚的种子在第二年春季发芽的比例很低。黄连的种子。皂角种胚的生长和萌发需要高-中-低-中的温度顺序，而8月份或以后播种的种子没有经历足够的高温期，只有一部分种子萌发。这些结果是世界上首次报道心脏类植物种子休眠，为种子生理生态研究提供了有益的参考，为人工繁殖提供了有价值的信息。延龄草种子也具有小而不发达的胚状体。7月下旬散播的种子中的胚胎在第二年夏天生长，胚胎生长后不久就出现了胚根。子叶在越冬后的春天出现。对种子进行温度处理，以确定萌发所需的温度。然而，我们仍然没有找到有效的温度处理方法。

In northern part of Japan, there are several aesthetic native plant species and some of them have the seeds which need two winters from seed dispersal to cotyledon emergence. The goal of the study was to reveal the germination ecophysiology and seed dormancy mechanism of such seeds.Seeds of Cardiocrinum cordatum var. glehnii have underdeveloped embryo when seeds are dispersed. It took 18 mo from seeds dispersal to radicle emergence and 19 mo for cotyledon emergence in nature and they have deep simple morphophysiological dormancy. However, temperature sequence 25/15℃ (60d)→15/5℃ (30d) →0℃ (120d) →15/5℃ using incubator shortened the period from sowing seeds to radide emergence to 7 or 8 mo. Seeds collected in autumn, stored at 5℃, and sown by June in the following year germinated more than 88% in the next spring. On the other hand, seeds sown in August in the following year or later germinated to low percentages in the next spring. Seeds of C. cordatum var. glehnii need temperature sequence high-moderate-low-moderate for embryo growth and germination, however, seeds sown in August or later were not exposed to enough period of high temperature and then only a part of them germinated. These results are the first report on seed dormancy of genus Cardiocrinum in the world and contribute to the field of seed ecophysiology; further they are valuable information for the artificial propagation.Seeds of Trillium camtschatcense also have small and underdeveloped embryo. Embryos in the seeds dispersed in late July grew during the next summer and radicles emerged soon after the embryo growth. Cotyledon emerged in the spring after winters. temperature treatments were applied to the seeds to determine the temperature requirement for germination. However, we still did not find the effective temperature treatment.