Approaches to Germplasm Conservation

Germplasm resources is a very wide term that covers all the allelic resources spread in types ranging from most primitive wild progenitors to the highly bred cultivated varieties and strains. The scope and procedures of collecting, conserving and utilization of these resources depends upon their biological status. The germplasm may fall in either of the following categories:
(a) Wild relatives
These are the types which contributed directly or indirectly to the evolution of a crop plant but still survive only in the wild stage. Being strictly the product of nature, these types carry useful genes to protect plants against all types of stresses e.g. diseases, pests and are endowed with hardiness, tolerance to heat, frost, drought, excessive water etc. On account of the requirements of their survival without human care, these types have characteristic behaviour for germination, growth patterns, reproductive behaviour that makes their use in plant breeding bit difficult.
(b) Weedy relatives
There is a strong chaing of transformation from wild to weedy and then to cultivated form for each crop where weedy relatives serve as a bridge for transfer of genes. Wild species survive under situations that are undisturbed by man for cultivation. The weedy relatives are, therefore, easy to grow under normal crop condition and serve as a vehicle of transferring genes from wild to cultivated types.
(c) Primitive cultivars or land races
These types represent the product of nature or the effect of human selection under cultivation particularly developed over a prolonged period of time. The original material might have been selected by each farmer according to his requirements and the environmental factors splitting it into different types. These primitive types survive for such a prolonged period only on the best source of genes for resistance. The fact that these are farmer's varieties avoids all the problems associated with collection, maintenance and use in plant breeding.
(d) Modern cultivars
This type of germplasm represents the assembly of useful genes whose survival is dependent upon human interference. Such populations carry a greater bulk of useful allelic resources for most of the economically important characters.
(e) Advanced breeding lines
This represents the most advanced product of plant breeding activity which combines useful genes wherever from these are available. Elite genetic stocks, as these usually are called, serve as the most useful type germplasm which can be easily maintained and used for further breeding.