Correlations among morphological and biochemical traits in high-CBD hemp (Cannabis sativa L.)

Authors: STACK, GEORGE - Cornell University; Carlson, Craig; TOTH, JACOB - Cornell University; PHILIPPE, GLEN - Cornell University; ROSE, JOCEYLN, KC - Cornell University; SMART, LAWRENCE - Cornell University

Submitted to: Plant Direct
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2023
Publication Date: 6/19/2023
Citation: Stack, G., Carlson, C.H., Toth, J., Philippe, G., Rose, J., Smart, L. 2023. Correlations among morphological and biochemical traits in high-CBD hemp (Cannabis sativa L.). Plant Direct. 7(6). Article e503. https://doi.org/10.1002/pld3.503.
DOI: https://doi.org/10.1002/pld3.503

Interpretive Summary: Hemp is a promising crop that has uses in diverse markets, such as food, animal feed, cosmetics, textiles, and medicine. Specialized chemical compounds produced in the floral tissues of hemp (cannabinoids) have many therapeutic uses, and the amount of these compounds are critical in determining the value of a variety or crop. Since its recent federal deregulation, there is limited knowledge of how plant shape and size affects the concentration of these compounds in different parts of the plant. This is important for maximizing the value of a hemp variety or crop. In order to advance more efficient production systems, we measured cannabinoids throughout the canopy for 32 hemp varieties in different environments. By sampling floral material in different sections of plants, we identified groups of canopy shapes and sizes that distribute equal amounts of cannabinoids across the canopy or otherwise concentrate them at the top. In addition, this research discusses novel canopy traits and those most economically important to growers. The relationships among growth and chemical traits reported in this research will inform future decisions by growers, regulators, and plant breeders, as well as deepen our current understanding of within-plant variation of specialized chemicals.

Technical Abstract: Cannabis sativa L. has emerged as a promising crop due to its multitude of uses including production of cannabinoids, a class of compounds concentrated primarily in the glandular trichomes of female inflorescences. In developing improved cultivation systems for high-cannabinoid cultivars, scientists and cultivators must consider the optimization of complex and interacting sets of morphological, phenological, and biochemical traits, which have historically been shaped by natural and anthropogenic selection. Understanding factors that modulate cannabinoid variation within and among genotypes is fundamental to developing efficient production systems and understanding the ecological significance of cannabinoids beyond human use. To that end, thirty-two high-cannabinoid hemp cultivars were characterized for traits including growth rates, initiation of flowering, and accumulation of cannabinoids using regulatory-style shoot-tip samples. Additionally, a set of plant architecture traits, as well as wet, dry, and stripped inflorescence biomass were measured at harvest. One plant per plot was partitioned post-harvest to quantify intra-plant variation in inflorescence biomass production and cannabinoid concentration. There were strong correlations between in-season and post-harvest cannabinoid measurements. Some cultivars showed intra-plant variation in cannabinoid concentration, while many had a consistent concentration regardless of canopy position. There was both intra- and inter-cultivar variation in plant architecture that was correlated with intra-plant distribution of inflorescence biomass, and concentration of cannabinoids sampled from different positions within a plant. These relationships among morphological and biochemical traits will inform future decisions by cultivators, regulators, and plant breeders as well as our broader understanding of intra-plant variation of specialized biochemicals.