The Orchidaceae is one of the largest plant families on Earth, including almost 10% of all flowering plant species. Lots of articles have been produced on their taxonomy and population biology. Still, early stages of this plant group are covered with much mystery. Germination data is often rather old and sometimes repeated from article to article without further proof.
Preservation of seed bank and germination is practically not studies in wild orchids, mostly because the seeds are so minute and uncomfortable to study with ordinary methods. Whigham and Rasmussen, who developed a method of sowing seeds in slide frames, started in situ studies in 1995. The same method with slight modifications can be used in our study.
In our proposed study TTC test, which is still most often used method in several seed collections (ISTA, 1999), will be performed on seeds picked up from soil after a period of time to test if the non-germinating seeds are potentially able to germinate later. Also this test is used for seeds that have been recently harvested and held under different conditions to determine their viability and germinability.
Terrestrial orchid seeds have conventionally treated as transient. Some studies have indicated that the seed bank of some terrestrial orchids is capable of lasting more than one year. Still there are very few studies on the germination behavior of different terrestrial species under natural conditions, mainly because the seeds of all orchid species are tiny and extremely inconvenient to handle with traditional methods. We hypothesize that different orchid species can be very different in their germination behavior and seed properties, and these differences can determine the rarity and vulnerability of an orchid.
The main objectives of the project would therefore be determining germinability, germination times and requirements, length of viability of the seeds of several Estonian orchid species. We plan to assess the possibilities of storing terrestrial orchid seeds collected from nature. Also we would like to clarify the character of the natural orchid seed banks.