1. The total genetic information in all the genes in a breeding population at a given time.

2. In PGR: Use is made of the concept of 1, 2 and 3 (primary, secondary and tertiary) gene pools. In general, members of a 1 gene pool are inter-fertile; those of the 2 gene pool can cross with the 1 gene pool under special circumstances; with the 3 gene pool, extreme techniques are required to achieve crossing.