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George Stack, Maylin Murdock, Alex Wares, Stephen Snyder, Jacob Toth, Jamie Crawford, McKenzie Schessl, Nicholas Genna, Glenn Philippe, Zachary Stansell, Jocelyn Rose, Ginny Moore, and Larry Smart
Cannabinoids are produced in greatest concentrations in unpollinated female inflorescences. Pollination decreases the value of material for both market classes of cannabinoid hemp, diluting the concentration of cannabinoids in floral biomass used for extraction, and resulting in unmarketable seeded material for smokable flower products.
In other plant species, such as watermelon and banana, triploid cultivars are sterile and do not produce any seeds. Development of triploid hemp cultivars, which do not produce seed even in the presence of hemp pollen, could lead to greater and more reliable yields for growers and less conflict between producers of cannabinoid hemp and grain/fiber hemp. As seen in Fig. 1, triploids can be produced by first doubling the genome of the diploid seed parent – using a chemical treatment to recover a tetraploid individual. That tetraploid (4X) seed parent is crossed with the diploid (2X) pollen donor to produce seedless triploid (3X) F1 hybrid cultivars. Oregon CBD has accomplished this by doubling their CBD and CBG seed parents and crossing them with their autoflower pollen donor to produce triploid F1 hybrids.
In 2021 and 2022, we evaluated the performance of diploid and triploid cultivars at sites with and without pollen pressure (Table 1).
Table 1. Diploid and triploid cultivars from Oregon CBD trialed in 2021 and 2022
| Cultivar | Ploidy | 2021 | 2022 |
| Lifter | Diploid | X | X |
| Lifter Seedless | Triploid | X | X |
| Sour Lifter Seedless | Triploid | X | |
| Suver Haze | Diploid | X | X |
| Suver Haze Seedless | Triploid | X | X |
| Sour Suver Haze Seedless | Triploid | X | |
| White CBG | Diploid | X | X |
| White CBG Seedless | Triploid | X | X |
| Pine Walker Seedless | Triploid | X | |
| Sour RNA Seedless | Triploid | X |
Key Results:
- At pollen-free sites, triploids had similar concentrations of cannabinoids to their diploid counterparts. At pollen-challenge sites, triploids had greater concentrations of cannabinoids than diploids.
- Triploid cultivars produced similar concentrations of cannabinoids at pollen-free and pollen-challenge sites.
- Triploid cultivars produced significantly less seed than diploids at the pollenchallenge site, though they did produce some viable seed.
Table 2. Cannabinoid and seed production data. Total cannabinoids were quantified in regulatory-style inflorescence samples at 3 and 5 weeks post flowering, as well as in stripped floral biomass. Seed production was quantified by weight and number of seeds relative to the amount of stripped floral biomass produced by each plant.
Acknowledgements: This project was funded by a grant from the Foundation for Food and Agriculture Research (FFAR) with matching support provided by Oregon CBD.
