Trubanova, N.; Pender, G.; McCabe, P. F.; Melzer, R.; Schilling, S.

Hemp (Cannabis sativa L.) is a high-value multi-purpose crop with applications ranging from the medicinal use of its secondary metabolites to carbon-sequestering building materials. To fully capitalise on the potential of hemp as a crop for more sustainable agriculture, detailed phenotypic and genotypic characterizations are required in order to inform targeted breeding programmes. Here, we present a detailed morphological and genomic analysis of 10 hemp cultivars. We found high variability in agronomically important traits such as flowering time, plant height, and biomass in most of the hemp cultivars tested. Additionally, genotyping by sequencing demonstrates that genetic differences are pervasive, both between hemp cultivars as well as between individuals of a single cultivar. The significant genetic and phenotypic variability we observe in hemp contrasts with other crops, where cultivars are often phenotypically and genetically relatively uniform. We argue that the variability of hemp is an asset for breeding and increases the potential for further improvement of the crop but is also a challenge for today\'s highly automated agriculture that relies on phenotypic uniformity.