BP Singh

58 R.K. Saxenacommon cereals. Thus any store which operates at -IOcC is alsoreferred as a long-term store. Present indications suggest thataccessions stored at -IO°C will require monitoring and regenerationtwice as frequently as those at -20°C. Consequently it isreconunended that new facilities should adopt -20°C.Processing of seed for conservation at NBPGRThe NBPGR receives exotic and indigenous germplasm ofagri-horticultural crops (orthodox seeds) from different sources forlong term storage in the National Genebank. Before it is finallystored! conserved, it passes through following channels:1. Registration: Seed received from different sources, arechecked and duplicate samples rejected. Only new arrivals are,registered. The accession number once assigned is not re-assignedeven if seed viability during storage is lost.2. Seed cleaning and purity analysisi) Seeds are inspected and under-sized, shrivelled,immature seeds are screened out, 'ii)iii)iv)Broken and damaged seeds are rejected,Diseased seeds, insect attacked and seeds affected by. nematodes are rejected andGrass and cereal florets, empty glumes, lemmas, sterileflorets of grass and cereals are rejected; weed seeds arealso separated out. Samples of the clean seed lot aresubjected to initial seed viability tests (by germinationtests) following 1ST A guide lines. Seed samples showingviability standard of 85% or more are accepted.3. Seed germinationi) Rolled towel test: Generally medium and large seeds suchas those of c~reals, maize, grain legumes, oilseed crops (sunflower, 'safflower etc.) and vegetables (okra, cucurbits etc.) are tested forge1,"mination by this procedure. Towel papers are spread on topof each other and then soaked in water. A waxy paper is keptbelow the towel paper. On rough side of waxy paper, date ofexperiment and accession number are written. Normally 25 or 50seeds are plc.lll'd on top of the uppermost sheet in a fairly regular