Considering the little room for error that cannabis growers have, it is critical to ensure that their plants consistently produce high-quality flowers. One of the ways to stimulate better growth is the use of PGPMs, Plant Growth Promoting Microorganisms, in nutrient solutions. As the Spanish grower ReLash Lab explained to us in a previous article, Trichoderma Harzianum is one of those fungi that boosts cannabis plants’ growth and positively affects their agronomic characteristics.
To gain a better understanding of also different fungi that are beneficial to cannabis plants, Ioanna Kakabouki et al. have conducted an experiment in soilless cultivation to see how the arbuscular mycorrhiza fungus Rhizophagus irregularis affects the plants’ growth – considering also its well-established characteristic of reducing the transplant shock for seedlings. To evaluate the effects, the experiment was conducted by applying three treatments to the seedlings: specifically, 40,80, and 120 fungus spores per liter of nutrient solution. To assess the difference with the untreated plants, the researchers looked at root length, stem length and weight, stem diameter, and N and P content.
Results of the experiment
When collecting the results, the scholars noticed that Mycorrhizal colonization improved greatly with higher doses of the fungus, while it basically stayed the same with lower doses. At the same time, the root length increased by almost 25% compared to the control. Yet, no significant benefit was recorded for plant height, shoot fresh weight, or diameter.
On the other hand, dry stem weight experienced higher values after the highest treatment. All in all, the authors say that ‘the total dry weight of aboveground and underground cannabis tissues is enhanced by increased fungus doses.’ Thus, Arbuscular Mycorrhizal Fungus (AMF) colonization contributes to plant growth enhancement.
Still a lot to uncover
Although the results of the experiment look promising in the race to find a better cultivation methodology, there are still a few things to understand about the relationship between that fungi and cannabis plant growth. As the scholars pointed out, “Besides their effects on nutrient uptake of the plant, Al-Arjani et al. reported that Arbuscular Mycorrhizal Fungus enhance the production of phytohormones.”
So, AMF does improve plant growth, and also seems to be beneficial to reduce the transplant shock for seedlings. This anyway is also an effect generally attributed to a well-developed roots system that is able to support the plant through environmental changes and all of that. That is why the authors finally remark that “further research should be conducted regarding the mechanisms and the biochemical pathways behind the beneficial interaction between Rhizophagus irregularis and cannabis seedlings.”