A landrace is a plant variety which has adapted to its local environment and can be considered the oldest type of crop cultivars. Landraces originally started from wild populations and over time and generations have developed a distinct identity. Natural selection by climatic conditions in South and Central Asia initiated the divergence in wild cannabis populations, with phytochemical divergence being driven further by domestication. Landraces have adapted to best suit their local climate, with water availability, soil type, and available ripening time all playing an influence. These populations are maintained by wild open pollination, or by local farmers saving seeds. As a domesticated crop, the gene pool of landraces is significantly wider and more diverse than a commercial variety, while maintaining a distinct identity. An enhanced genetic diversity assists in maintaining crop health and vigour across generations, making it more adaptable and resilient to new environmental pressures such as pests, drought or flooding.
Wild-type populations are an excellent source for strengthening the genetic basis and accumulation of desirable variation which has been lost due to selection pressures and adaptation in modern cultivars. While overall horticultural quality and harvest of improved hybrids has increased year on year, this improvement has been accompanied by a reduction in allelic diversity. Association mapping and genomic prediction studies can be used to identify novel sources for resistance to abiotic and biotic stresses by identifying alleles for enhancing yield and abiotic stress adaptation, thus raising the productivity and stability of crops in vulnerable environments.