Seed Collection, Storage & Banking

Seed is a container packed with fantastic things from parent to a new life that can grow into a big tree and live for a hundred years. Therefore, seed is a foundation for forest restoration and conservation projects. To maintain their viability, seed should be collected, stored, and treated properly.

Seed collection

In the seasonally dry forests of northern Thailand, many tree species fruit in every month of the year, so at least one seed collection trip is needed every month. Fruit or seed trees are usually collected when they are fully ripe (changing their colors/attracting seed-dispersing animals/starting to split open), at the best time followed phenology study. It is usually better to cut fruits from the tree branches rather than to pick them up from the ground.

One of the most important things to maintain genetic diversity, fruits/seeds should be collected from many trees, at least 10 parent trees. Each time you collect seeds from a new species, give that species a unique species number and record essential details about the seed batches collected such as species details, location, collection date/time, etc.

For most species, the seeds should be removed from the fruits and cleaned before sowing or storing. To select vigor seeds and eliminate fungi infection, the various types of processing required depends on the fruit types.

Seed banking

Seed bank project has importance objectives to conserve diversity of plant/tree species through their seeds and keep seed resources for forest restoration project. The mission of seedbank included many procedures such as seed collection and identification, seed cleaning and pre-processing of storage and suitable storing methods.

Our goal for seed banking project is preserving native tree seeds and containing their information as much as possible, it can be a resource for forest restoration and research that benefits the public.

Seed storage for seedbank

The suitable storage of seed after seed collection is very importance to preserve their vigor and vitality. The reasons for this process are; 1) we need to keep the seeds as long as possible, to be the resources for next year. 2) we need to wait for the seasonable tiling production, the seed might not be sown immediately after seed collection, and 3) seed might be transported to other target areas where they are rare to find trees or seeds.

The challenging of seed storage for seed banking is the storage design for each different species and their storage behavior which respond to different conditions. Some seed can last from a few years to a hundred years. In contrast, some species cannot survive under desiccation  or resist the effects of drying, so seeds cannot be stored conventionally. Therefore, the morphological characteristic and seed storage behaviors are essential information to determine the appropriate storage method for each species.

Identify seed storage behavior

Seed can be identified to three groups following their response to dry condition or seed storage behaviors.

• Orthodox seed – seeds can tolerance to desiccation and reduce percent moisture content to at least 5% without damage or lost the viability to germination. The longevity is increased by decreasing of seed storage moisture content and temperature. 
• Recalcitrant seed – seeds cannot survive desiccation below a comparative high moisture content, responses to loss of water in seed. Recalcitrant seed can be damaged by remaining water that creates ice crystals during conventional storage.
• Intermediate seed – seed has the combination characteristic between orthodox and recalcitrant seed. Intermediate seed is able to survive desiccation to dry seed storage moisture content, sometime 7-10% moisture content. However, it is sensitive to low temperature storage.

The information about seed storage behavior has been collected and presented in the seed banking database, but that only few percent of species in Thailand. It is difficult to identify seed to orthodox, recalcitrant or intermediate by their morphology. A large number of species lack of storage information and necessary to clarify their storage behavior. FORRU is one of research units that try to gather seed information. Our mission is to do research studies about tree species that related to species conservation and forest restoration project. The projects have been organized by our team included CMU professor, researchers and students. We star to survey target tree species, their population, location and collect plenty of mature fruits for perfect seeds. Most of collected seeds are used for seedling production in tree nursery, but some of them are using for the study of morphology and seed storage behavior.

Due to rapid environmental change or global climate change can be negative effect on tree species reproduction and related to low possibility to conserve plants within their habitat.  We hope the storage seed can be germinated and reintroduced to their original habitat or used in scientific research. Beside from that, we have project partners who share the information and practical techniques with us such as Millennium Seed Bank KEW garden, Doi Suthep Nature Study Center and Doi Suthep-Pui National Park