BP Singh

Use of Tissue Culture Techniques in Exchange 71are being employed. For example, efficiency of collection ofcoconut and cocoa germplasm was greatly improved by using invitro techniques (Withers, 1987). Tissue culture techniques canthus reduce the bulk and make handling and transport ofgermplasm more simple and efficient.5. Better product quality through in vitro culture : Seedexchange is often resorted to in perennial tree crops owing todifficulties in conventional clonal multiplication and transport, andalso to minimise quarantine risks. However, in heterozygousplants one is often interested in introducing spedfic, elitegenotypes. (e.g., female plants in monoecious species). By tissueculture multiplication unique genotypic constitution can bemaintained and,made available to the indentor. Similarly, insteadof budwoods or cuttings, rooted plantlets ready for planting in soilcan be supplied thus obviating the need for special skills at thereceiving end. Furthermore, in vitro production of storage organslike tubers, bulbs, rhizomes etc. can help in efficient exchange andestablishment of germplasm.6. Tissue culture at the receiving station/quarantine station: Atthe receiving end also tissue culture techniques can be employedfor salvaging and mass multiplication. Samples of in vitro materialcan also be conserved in tissue culture to meet future demands.This will reduce repeated introduction of the same material andreduce workload on exchange and quarantine: services.7. Rejuvenation and establishment: Poor germinability of seedsamples is a common complaint in germplasm exchange. Lowgerminability may be due to several factors such as dormancy,hard seededness, low viability or vigour etc. So long as embryo isviable, one can hope to recover complete plants through tissueculture. Recently, by embryo culture, Dilday et ai. (1994) were ableto recover a11126 accessions of rice, stored for more than 19 years,that failed to germinate in the field and in standard laboratorygermination tests. Tissue culture can be particularly importantwhen introducing rare germplasm or when sample size is verysmall (e.g., wild species).8. Tissue culture and management of germplasm exchange:In vitro cultures of tropical, subtropical and temperate crops canbe maintained and multiplied under a single roof. Hence overall