Preservation of germplasm


Method of preservation is divided according to the type of germplasm:
seed ornon-seed(clonal materials).
Storage of seeds:
According to storage tolerance of the seeds to low temperature and dry environment, seeds are further divided into storable (orthodox) and non-storable(recalcitrant) types.
1.Orthodox type:
These include small-seeded grain crops and vegetables. They can be stored for a long time under low-temperature and low-humidity environment and are separately stored in long, medium and short-term storerooms in accordance to the purpose of storage.
 
 a.Long-term storage:
   With storage conditions of -182J and 
   303% RH, long-term RH, long-term
   preservation is provided mainly for the
   comprehensive base collection. Careful 
   collection. Careful identification and
   selection precedes before storage. About
   240,000 accessions will be stored. Stored
   materials will not be used for exchange;
   they are only preserved for regenerating
   fresh seed and periodically examined for
   seed viability level.The purpose of this
   storage is for the perpetuation of the 
   seed stocks. Life expectancy of seed 
   preserved in long-term storage at this 
   Center will last from 30 to 50 years.
 b.Medium-term storage:
With storage conditions of 12J and 403% RH, this storage is provided solely for the seeds of actively used materials. This storage will accommodate 250,000 accessions or samples that will be used for distribution, exchange, multiplication, and evaluation purposes. The seeds will also supplement the base collection in long-term storage. Regular germination tests and seed regeneration are required for materials in this storage in order to maintain their viability.
 c.Short-term storage:
With storage conditions of 102J and 403% RH, working materials frequently requested or used, such as those parents and progenies of the breeding materials or those with particular characteristics for research purpose, are kept in this storage room.

 2. Recalcitrant type:
Those classified as non-storable or recalcitrant type of seed, which can not be stored under low temperature and low humidity conditions, are certain vegetables, cocoa, logan and lichee as well as those seeds that are large nd fleshy. Such seeds may be stored in low temperature ranges (0-10J) for short periods such as 1-5 years.



Conservation of clonal( vegetatively reproduced ) materials:

@@Preservation of clonal materials is attained by:

@@1.tissue culture.
@@2.cold storage.
@@3.cryopreservation in liquid nitrogen.
@@4.field maintenance






Preservation of plant tissues in vitro

Tissue culture for many clonal materials in artifical media are more space-saving of intensively managed than field plantings. Tissue culture also ensures virus-free condition in germplasm exchange.





Cold storage

Bulbs, tubers and rhizome of certain crops can be stored at 0-15J under high humidity for several months or up to one year. It is also a type of short-term storage.





Super-cold storage(Cryopreservation)

Embryos, tissues and pollen grains can be stored for long periods, in liquid nitrogen (-196J). But its practice use is yet to be developed as crops require different cooling and thawing treatments and have different viability level.



Field conservation

Germplasm materials such as fruit trees, potatoes and grasses are grown in nurseries field for conservation. So far TARI has maintained field nurseries at different elevations above sea level, totalling seven conservatory gardens. One nursery at TARI is used for quarantine and isolation reproduction purpose.



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