Hemp has been used for industrial purposes for a long time in European history. [1] The stems can be used to produce various fibers or insulation material, the oils have been shown to have therapeutic applications, and the seeds can be used to generate food sources. As popularity continues to grow, it becomes vital to develop cultivars that will maximize yields of all of these materials to efficiently utilize this plant.
Comparing the Cultivars
The University of Udine compared eight cultivars of monoecious hemp to determine what factors make the most difference in maximizing yields of seeds, stems, and oil harvested at full flowering. [2] Of the eight variations that were grown on the university’s experimental farm, four originated in Hungary, two were from France, with one each from Romania and Ukraine, respectively. These variants of hemp were selected to represent a wide range of maturation time, ranging from “Very Early” to “Late” to provide a broader spectrum of data to compare. It is worth noting that, in the years 2016 and 2017 when the plants were grown, the average rainfall was below the previous 25 years’ average (“64% in 2016 and 44% in 2017”) and the average temperature was above the previous 25 years’ average (“about 0.5 °C in 2016 and 1.4 °C in 2017”).
Results and Conclusion
Each variation saw an average of 75% emergence from the seeds planted, with an average maturation period of 3-4 months. Monoecious cultivars are meant to produce both male and female flowers, but all the Hungarian varieties saw above-average male flowers (ranging from 11%-40% of the total amount of flowers) compared to the other varieties, where the percentage of male-only plants remained lower than 6%.
Additionally, seed production was lower than expected (28% lower in 2017 than 2016). The authors of the study concluded that this was due to environmental concerns stating, “high temperatures at the anthesis stage are detrimental for seed yield because they interfere with pollen production and floret fertility, affecting pollination phase and the first development of the embryo rather than the ending of the seed filling.” [3]
On the other hand, biomass and oil production for all cultivars was at or above the goal for European production. The two variations that produced the best results were both from France. One (named “Futura”) produced the most inflorescences, seeds, stems, and essential oils, and the other (called “Fedora”) was determined the best for food supplies as it produced a high number of seeds and oils. The authors concluded that focusing on the right cultivars, choosing the two French over the Hungarians, would lead to better yields, but it depends on the ultimate purposes of the hemp growers.
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References
[1] Allegret, S. The History of Hemp. In Hemp: Industrial Production and Uses Hemp; Bouloc, P., Allegret, S., Arnaud, L., Eds.; CAB international: Bar sur Aube, France, 2013; pp. 4–25. ISBN 9781845937928.[2] Baldini M, Ferfuia C, Piani B, Sepulcri A, Dorigo G, et al. The performance and potentiality of monoecious hemp (Cannabis sativa L.) cultivars as a multipurpose crop. Agronomy. 2018;8(9):162. https://doi.org/10.3390/agronomy8090162 [journal impact factor = 2.24; times cited = 27]
[3] Chimenti, C.A.; Hall, A.J. Grain number responses to temperature during floret differentiation in sunflower. Field Crops Res. 2001;72:177–184. [journal impact factor = 5.388; times cited = 45]
