Gene pool: The sum total of genes in a crop species is referred to as genetic or gene pool or genetic stock or germplasm. In other words gene pool refers to a whole library of different alleles of a species. Germplasm is the primary element for a plant breeder to initiate plant breeding program.

Some important features of germplasm or gene pool are given below:
1. Gene pool represents the entire genetic variability of a species.
2. Germplasm includes both cultivated & wild species or relatives of crop plants.
3. Germplasm is the basic material for launching a crop improvement program.
4. Germplasm is collected from the centres of diversity, gene banks, gene sanctuaries, farmers fields, markets, seed companies.
5. Germplasm may be indigenous or exotic.