Seed extraction

In the seed extraction process, the cones open up and release their seeds. It may sound simple, but it requires a qualityassured work method so as not to damage the valuable seeds. For many years, SCA has hired a contractor for its cone kilning, but now we can process a large share of the cones by ourselves.

Own design

SCA’s personel at Wifstamon tree nursery have developed both a kiln for drying and a machine that separates the seeds from the cones.

The cones come from the pine and contorta pine seed cultivations sites that SCA has around the Sundsvall area. The cones are harvested in autumn and then mature on large racks in a greenhouse and stored in cold storage until seed extraction begins in January.

SCA only process pine cones so far because spruce cones require a different method.

Kiln and seed separator

From the cold store, the cones are moved to one of Wifstamon’s greenhouses. It is home to tens of thousands of small seedlings during the spring and summer months, but in winter these are replaced by a large container and a blue machine with a large hopper and net-clad drum a couple of meters long.

The container is the hot air kiln where the cones are dried for about 24 hours to open them up.

The blue machine is the seed separator, a kind of giant tombola drum, where the open cones are shaken around so that the seeds extracts and fall down through the net and can be collected in a plastic bin.

The cones that leave the separator are collected on their rack. They are then watered so that they close again, before going back into the kiln for a second round of drying, and then another round in the separator. Each pine cone has to be processed twice to extract all the seeds. There are usually around two kilograms of seeds.

Help from Skogforsk

To gauge its success with the seed extraction, SCA send a couple of test batches of seeds to Skogforsk (Forestry Research Institute of Sweden). After kilning, the seeds retain their bracts, but at Skogforsk’s seed service in Sävar, the bracts are removed and germination is tested.

To have the right germination rate is hugely important for seedling survival and growth. If all the results from the analyses looked good, SCA can proceed with the extraction.

All seeds are then transported in paper sacks to Skogforsk’s seed service. They handle all seeds from SCA, and from some others in the industry. Skogforsk offers a range of services such as removing seed bracts, cleaning and sorting seeds, as well as analysis, advice and development of new seed treatment methods. 

Follow the seeds

When the seeds come back to NorrPlant after a couple of months, they are bractless, sorted and ready for sowing. SCA sow most of the seeds in the current year, but can also store seeds in the freezer for future seasons.

Thanks to SCA’s extensive seedling monitoring, which follows the development of selected seedlings up to the age of ten years, it will be possible to monitor these seeds from the first in-house kilned batch. This helps SCA to control that seeds can produce high-quality seedlings and stable trees that grow well.