Industrial hemp breeding and genetics

Breeding Cannabis sativa L. is challenging due to high heterozygosity and genome complexity. The lack of genetic data has slowed down breeding processes, but recently this plant is gaining more and more scientific attention and genomic data are accumulating. Based on the Δ9-THC (delta-9-tetrahydrocannabinol) content, C. sativa L. is divided into drug-type or medical cannabis (high Δ9-THC content) and fiber-type cannabis or industrial hemp or simply hemp (low Δ9-THC content). This chapter focuses exclusively on hemp (fiber-type cannabis) and provides insight into hemp genetics (including description of plant appearance and taxonomy) and breeding of this allogamous plant (breeding objectives, methods, and obstacles). Finally, the breeding procedures of some European hemp varieties are described. The future perspective of hemp breeding seems to focus on improving cannabinoid content and cannabinoid ratio.