A collection of plants and seeds having diverse alleles of all the genes of a crop is called
herbarium
germplasm
gene library
genome
Germplasm collection refers to a group of plants or seeds with a variety of alleles for each gene in a crop. It serves as an illustration of ex-situ biodiversity protection. Ex-situ conservation involves protecting biological diversity-related elements away from their natural settings. It is accomplished by protecting species, both wild and domesticated, as well as genetic resources. Gene banks, microbial cultures, cryopreservation, etc. are some examples.
So, "Germplasm" is the right response.