(ii) Cryo Bank (storage at -1%° C) and

(iii) Tissue Culture Repository (10-25°C).

It is also reconginzed that facilities in India are already available for the medium and long term storage of seeds of those crop plants, that can withstand high drying and low temperature. However, in vitro conservation techniques including tissue culture and cryopreservation offer distinct advantages.

In view of this, in 1986 with the financial support from the Department of Biotechnology (Govt. of India), NFPTCR (National Facility for Plant Tissue Culture Repository) was established at NBPGR (National Bureau of Plant Genetic Resources) located in New Delhi.

For the development of this facility, initially a budget of Rs 2.96 crores was provided for a period of five years (1985-1990). An additional sum of Rs 2.80 crores has been sanctioned for the next five years (1991-1995) for Continuation and expansion of tissue culture facility.

A range of crops like millets (pearl millet, minor millet), oil seeds (Brassica spp., sunflower, sesame), vegetables (onion, carrot, chilli, amaranth, turnip, radish, tomato), pulses (Vigna spp.) and narcotics (tobacco, poppy) have been maintained for several years in liquid nitrogen without any decline in viability or vigour.

The strategy of desiccating excised embryonic axes has led to the successful cryopreservation of even recalcitrant seed species (e.g. tea, orange, neem) and is being tried for cocoa, jackfruit and almond, etc.

Short term or medium term conservation at NFPTCR are also being tried through long term root cultures, which are capable of regenerating in shoots (e.g. Citrus = lime). Similarly shoot cultures of banana, ginger, greater yam (Dioscorea a/ma) , and sweet potato could be maintained for 8-24 months at 25° C .

The sub culture interval for this purpose can be extended by using low temperatures ranging from 4°C to 15°C, although chilling sensitivity varies between species. This technique also allows to keep the tissue cultures free from viruses.