BP Singh

Medium and Long-term Storage of Seed Material in Gene Bank 59pattern so that they are ~pproximately equidistant. Another towelis then placed on top of the seeds. The basal 20-30 mm portionof the longer edge of all towels are turned up to form a lip toprevent the seeds falling out.The towels are then gently and loosely rolled to form a tubeof about 50-60 mm and tied with rubber band and kept ingerminator at a desirable temperature and period. The towels arerolled loosely, (tight rolling would prevent air circulation betweenthem and result in either no germination or abnormal germination)and are placed in the germinator. Where germinator maintainshigh humidity, the rolled towels can be held with rubber band andkept upright in cages within the germinator. If the germinationtest is to be conducted in incubators where relative humidity is notcontrolled, water is sprayed over the towels every 2 to 3 days.ii) Filter paper: Normally 9 cm diameter filter papers are used.In some cases, larger and smaller filter papers and petri dishes areused. The small seeded crops e.g., tomato, brinjal, chillies, Brassicaspecies etc., are subjected to germination test in petri dishes. Thefilter papers are soaked in water and placed in the petri dish.Normally 2 filter papers are required for each dish. Seeds areplaced on top of the filter paper and accession numbe! can bewritten on the petri dish lid by a glass marking pencil. Petri dishesare then kept in the germinator for recording tl:e viabilitypercentage of the accessions.iii) Agar media: It is an alternative to routine germination test.Agar.is a polysaccharide complex, which though insoluble in coldwater, dissolves slowly in hot water to a viscid solution. NewZealand agar or Japan agar is suitable for germination test. Oneper cent agar solution forms a stiff jelly on cooling, on to whichthe seeds can be placed for the germination test. For example, ina germination test at 20°C, the agar remains moist for 2 weeks orso, the initial seed imbibition environment may be more favourablefurther than on in agar paper substrates and potential problemsfrom imbibition injury can thus be reduced.iv) Sand media: The sand consists of uniform particles and havea pH between 6.0 and 7.5. Before use (i) the sand should be sievedwith 0.8 mm diameter holes, the sand particles which pass throughthe sieve are used and (ii) must be sterilized at lS0°C for 2 hours.During heating, the sand must be turned regularly in order to dry