BP Singh

56 R.K. Saxenaspecies. One third of this sample is sealed in a separate packet andstored alongside the original sample under identical conditions(at -20°C) for monitoring germinability at regular intervals.ii) Viability testing: Initial germination tests are carried out ona minimum of 200 seeds drawn randomly from the originalsamples. Acceptable initial germination percentage should behigher than 85% for most species but lower levels are acceptablefor cotton and wild forms. 50-100 randomly drawn seeds are usedfor subsequent viability monitoring tests.iii) Seed drying: Seeds are dried in seed drying cabinetsoperated at 15°C and 15% relative humidity using silica gel asdesiccant based on adsorption system and appropriate air flow.iv) Seed storage conditions: Seeds dried to 5% moisture contentand sealed in laminated aluminium foils. Base collections arestored in modules operating at _20DC. Active collections are storedat 4 a C and 35% relative humidity.v) Regeneration: Undertaken when seed viability falls to 10%of the initial value. 100 plants or mme'-are ·preferred for thispurpose: ~ " .",-,'Seed Storage(a) Short Term Storage: The storage period for such seeds isbetween 1 year and 18 months. In the arid and cool agro-climaticzones, seeds of most cultivated species will maintain a highgermination capacity for as long as 18 months with only the baseshell of a storage. However, in warm and humid environments theviability loss is very rapid in the simple seed warehouse. Also,seeds of soybean, cotton, onion and several flower and tree specieslose germination capacity rapidly under warm humid storage andmay deteriorate in periods as short as 2 or 3 months in commonstorage under these climatic conditions. Therefore, in warm andhumid areas, and for seeds of these species, more substantialstorages are needed. The first requirement is some insulation tokeep the storage as cool as possible. One possibility is a false ceilingwith,ventilation between ceiling.and the roof. Heat inflow will bereduced by thick stone or brick wall or by a layer of insulation inwalls or ceiling. Ventilation fans to bring in cool night air can help,if it is not humid as to raise the seed to moisture contents to a levelthat allows attack by storage fungi.