**11.9 Thawing**

It involves the rapid thawing of the ampule containing the sample in a water bath at about 40 °C. They are plunged into warm water with swirling for rapid mixing just to the point where ice gets disappears and is important for the survival of tissues that the sample must be removed from the water bath after melting of ice. Tissues being thawed at a much lower temperature are then abruptly thawed following this step.

## **11.10 Determination of rate of survival**

Regrowth of stored tissue is the best indication of the survival of plant tissues. For this purpose, many viability tests are used which involve fluorescein diacetate staining, measurement of growth by cell number, and finally by calculating the dry and fresh weight. The two most popular methods are m


It provides the best opportunity for the conservation of endangered species being used for medicinal purposes. It also provides an ideal approach for the suppression of cell division to avoid further need for sub culturing. Pathogen free cultures and subcultures can be frozen and stirred when required and also provide a much suitable material for the selection of cold-resistant strains of mutant cell lines which later get differentiated into frost resistant cells or plants. The seeds may be stored for food crops or to protect biodiversity or reason for storage also varied which involve first drying of moisture to less than 5% and then stored at the much lower temperature of −18 °C or below it [64].
