"Today's medicinal cannabis production in Denmark is highly specialized and technical but simultaneously embedded in a framework that allows for limited use of some modern agricultural practices, for example, within vegetative propagation," according to a new study by the Department of Plant and Environmental Sciences of the University of Copenhagen.
"Propagation through vegetative cuttings is likely the most realistic practice in the Danish context, as it ensures consistent cannabinoid levels and similar growth patterns between plants," the researchers say. "In order to initiate rooting, cuttings are commonly exposed to auxins, a group of naturally occurring hormones that are important regulators in plants regarding the division, expansion, and differentiation of cells. While such products are not explicitly mentioned in the official documents regarding Danish medicinal cannabis production, their prohibition has been confirmed."
Therefore, the researchers say that novel methods to induce root formation in cuttings of drug-type cannabis are needed in Denmark. "Alternative rooting products for cannabis-based on biological compounds are available on the market, but few have been tested scientifically." For this study, the researchers focused on the root-inducing (Ri) ability that the rhizogenic bacterium Rhizobium rhizogenes possesses. "We specifically aimed to investigate whether R. rhizogenes inoculation could improve rooting in cannabis cuttings versus IBA or treated solely with water."
Results
The researchers found that rooting performance was best in IBA-treated cuttings with increased root length, root dry weight, and root/shoot dry weight ratio in cuttings compared to those treated with R. rhizogenes or water. "However, IBA inhibited shoot growth, which could be a problem later during commercial production establishment. Superior shoot performance was obtained in R. rhizogenes (A4 strain) and H2O-treated cuttings, thus showing advantages for the later establishment of commercial production of cannabis. These results are preliminary as a deeper analysis could be obtained on WinRhizo." A variation in cultivar susceptibility toward R. rhizogenes was noted in 38% of inoculated cuttings that were successfully infected. "The aeroponic growth unit was successful in generating rooted cutting in all tested treatments; therefore, it is an alternative to cannabis producers," the researchers add.
To read the complete research, go to www.mdpi.com
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