The demand for solventless cannabis concentrates is increasing due to the capacity to preserve the original plant's complex secondary metabolite profile. Such full spectrum extracts have been shown to be more effective in many cases than distillates with reduced complexity. Additionally, solventless methods reduce reliance on hydrocarbon solvents. Ice water or dry sieve hash production, for example, rely on a physical, solvent-free process that separates trichomes from the plant material, leading to a high-quality product that commands premium pricing. The efficiency of this process is governed by the trait of "washability," defined as the percentage of extractable trichome biomass per flower biomass, which is positively correlated with morphological factors like open flower structure and large, dense trichome heads with weak necks that easily detach from the stalk.

We aimed to identify the genetic loci responsible for improved washability to enable targeted breeding efforts. A diverse population of 436 cannabis plants was genotyped using an Illumina bead array. Plants were grown under standard greenhouse conditions, and washability was quantified in fresh frozen flower material using a miniaturized jar-tech extraction method to determine wash yield (mg trichomes/g flower material). Nested association mapping was subsequently performed to identify Single Nucleotide Polymorphisms (SNPs) associated with the washability trait.

We successfully identified and validated major genetic loci strongly associated with washability on two distinct chromosomes. The deployment of these genetic markers in our breeding program facilitates the precise selection of "good washers," enabling the development of cultivars with predictably high wash or dry sieve yields while preserving the desirable aroma and metabolite profile of the original plant. This marker-assisted selection approach is a critical step in advancing the quality and efficiency of solventless concentrate production.

Learning Objectives:

• Trichome and flower structures important for hash plants
  
  
• Genetic markers that are associated with traits that enhance solventless extraction yield