Genetic and environmental contributions to agronomic trait variation in Cannabis sativa

The establishment of a global medicinal Cannabis sativa (L.) industry has necessitated improving inflorescence traits, including elements of uniformity, quality, and yield across varying growth conditions for optimum production. To understand the causal mechanisms affecting variation in growth and yield, 20 ∆⁹-tetrahydrocannabinol- and cannabidiol-dominant varieties were used to assess agronomic traits in two different commercial settings. To aid standardization of floral traits in cannabis, we developed a novel phenotyping method using image segmentation to study inflorescence size and compactness. We apply this method to examine the undesirable indeterminate characteristic, “foxtailing,” that presents as elongated calyces and loose inflorescences. Our findings quantified both the genetic and environmental influences affecting expression of agronomic traits in cannabis and further highlight significant genotype-by-environment interactions. The findings suggest possible genetic control of foxtailing, evidenced by multiple varieties displaying the trait in differing environments. By uncovering the interplay between genotype and environment, and shedding light on inflorescence compactness, we provide actionable insights that can inform strategic breeding approaches and unlock the full potential of cannabis cultivation. These findings can help elevate productivity and make significant contributions toward yield optimization within different environments.