Types of Seed Collections
Based on the use and duration of conservation, seed collections are of three types: 1) Based collections, 2) Active collections, and 3) Working collections. These are briefly discussed as follows:
1. Base Collections:
Base collections include maximum number of accessions available in a crop. These are meant for long term conservation (upto 50 years or more) and are stored at 18- or 20 0C in hermetically sealed containers. The seeds are dried to 5+-1 percent moisture and have more than 85% initial seed viability. These collections are distributed only for the purpose of regeneration. These are used only when germplasm from other sources is not available for use in breeding. It is also known as principle collection and refers to the whole collection.
2. Active Collections:
This category of germplasm is actively utilized in breeding programmes and are conserved for medium term (8-10 years or more). These collections are stored at zero degree cesius with moisture content around 8%. Germination test is carried out after every 5-10 years to assess the reduction in seed viability.
3. Working Collections:
There collections are frequently utilized by breeders in their crop improvement programmes. These are stored for short term ( 3 to 5 years ). The seed is stored at 5-10 with moisture content of 8-10%.
This is another category of seed collections called core collection. It refers to a subset of base collection which represents the large collection or base collection. In other words, core collection is a limited set of accessions derived from existing germplasm collections, chosen to represent the genetic spectrum in the whole collection. The concept of core collection was proposed by Frabkle (1984).