ASHS 2025 Conference

Open to all attendees.

A forum for discussion of potential collaborations with regards to specialty crops – i.e. hemp, herbs, medicinal plants, and tropicals, breeding, production, etc.

The medical potential of cannabis (Cannabis sativa L.) is based on the complex chemical profile, comprising hundreds of secondary metabolites including cannabinoids, terpenoids and flavonoids. Cultivation conditions were demonstrated to affect plant development, function and production of secondary metabolites in cannabis. Understanding regulation of plant response to environmental conditions is key for development of optimal chemical profile for modern medicine. We have recently demonstrated sensitivity of the secondary metabolite profile in medical cannabis to mineral nutrition, with considerable responses to N, P, and K nutrition. Therefore, knowledge on the cannabis plant response to fertigation schemes is essential for the optimization of cultivation for production of high quality standardized material for the medical market, as well as for development of plant products containing specific desirable phytochemical profiles. In the talk, we will discuss our recent results concerning the potential of additional macronutrients and micronutrients to regulate plant development and the profile of active secondary metabolites in ‘drug-type’ medical cannabis. In pot experiments under controlled conditions, we demonstrated differential induction of changes in the cannabinoid and terpene profiles in ‘drug-type’ medical cannabis also by Ca, Mg, Zn and Mn. Furthermore, rate of uptake and deposition in the plants of individual macronutrients and micronutrients changes between the vegetative and the reproductive developmental stages, and along the reproductive phase.

As a short-day crop, Cannabis sativa, benefits from early-phase cultivation under long days to increase vegetative growth before transitioning to a generative flower phase. Previously, this long-day or “veg” phase has occurred under ceramic metal-halide lamps due to their relative increased blue content compared to the spectra of high-pressure sodium lamps used during the short-day or “flower” phase. Increased relative blue light during young plant production is desired due to the promotion of plant compactness and root development. Due to the relative efficacy of red diodes to blue, there is a benefit to maximizing red content without affecting plant performance. While many spectral recommendations arise from research in leafy greens and ornamentals, cannabis is cultivated under intensities three-fold greater, 600 µmol·m-2·s-1 during the long-day phase to 200 µmol·m-2·s-1 in leafy greens. Therefore, due to the high light intensity, it may be possible to produce optimal young plant quality under relatively low blue content. To test this, three cannabis cultivars rooted for 14 days were transplanted into 2-gallon coco coir bags and grown under long days with spectral treatments for an additional 14 days before finishing in a 12-hour short-day common environment. During the long-day phase, plants were exposed to high (~80%) or low (~40%) red at an average intensity of 500 µmol·m-2·s-1. Plant height at transfer to short days was similar regardless of light treatment. Additionally, final plant height and total flower yield after transfer into short days in a common environment was also similar. Therefore, it is beneficial to cultivate cannabis plants during long days under a high-red spectrum to minimize lighting cost while avoiding any negative morphology effects.

Cannabis (Cannabis sativa L.) is an annual herbaceous plant that belongs to the Cannabaceae family and produces economically important secondary metabolites called cannabinoids. According to the literature, controlled or induced water-deficit stress can increase secondary metabolite concentration in some essential oil-producing plants. Therefore, induced water-deficit stress (DS) may be an effective technique to maximize cannabinoid yield. This study investigated how different frequencies of induced water-deficit stress during the flowering stage affect cannabinoid yield and cannabis development compared to well-irrigated controls. By exploring the optimal stress conditions conducive to maximizing cannabinoid production, our study aims to offer strategic insights to inform cultivation practices and optimize cannabinoid production. This research contributes to advancing our understanding of cannabis cultivation techniques and may ultimately enhance the efficiency and efficacy of cannabinoid production on a commercial scale. Our hypothesis posits that induced water-deficit stress enhances plant secondary metabolism by modulating physiological responses. The treatments consisted of four frequencies of water-deficit stress periods during the cannabis flowering stage: WS0 – no stress, WS1 – one period of water-deficit stress, WS2 – two periods of water-deficit stress, and WS3 – three periods of water-deficit stress. The experiment was conducted using clones of the Heidi cultivar, which were randomly placed in the controlled-environment growth units. Weekly plant parameters included plant height, stem diameter, NDVI, chlorophyll content, photosynthetic efficiency, and stomatal conductance. After-harvest parameters included biomass partitioning, yield mass, bucked biomass, trichome density, and cannabinoid and terpenes levels. This is an ongoing study, but the preliminary data analysis shows interesting results regarding higher trichome density with no penalty for bucked biomass in the treatments under one period of water-deficit stress (WS1).

Dynamic lighting has recently evolved from theoretical research to commercial viability. As the cannabis industry faces increasing margin pressure, optimization techniques that enhance product quality while maintaining cost efficiency are essential for cultivation. But is dynamic lighting a silver bullet for enhanced cannabis cultivation? In this session Dr. Hawley will present research on UV, blue, red, and far-red light as it pertains to cannabis inflorescence quality and yield. New results will be presented that will inform how growers light their crops to maintain or exceed their current quality and yield while improving their lighting efficacy by 15% and reducing their lighting operational costs by 19%.