I want to add to this forum because I accidentally girdled a fairly large branch. I had used braided fishing line with a slip knot to pull down branches early on, one knot stuck and stayed tight as the plant grew.
I initially noticed yellowing on the two branches above where it was girdled, but did not know why at first. I thought nutrient deficiency or insect damage as they are outdoors with limited protection. I ended up finding the choked off point and cut the fishing line out with a razor blade. The girdling was probably 3/8 and inch deep at least.
Results from the control and experiment group. The trichomes on the girdled plant are 2-3 times larger than the other plants. I am going to girdle a main branch on the other plants today.
About me: I am a biologist, and I have spent time at tree seed farms where they harvest fir and pine cones for the seeds. They girdle the trees deep and stress the trees out with similar techniques as well. These trees are almost dead but continue to survive. As a result they produce more and larger flowers(cones) in this case.
My personal response and thoughts to this technique, is that stressing out a plant or tree will make it create an immune response to the threat and or injury. One way a cannabis plants protects its flowers is with sap, aka trichome production as it is a natural pest deterrent. It appeared trichome production and size was consistent throughout the plant even though only 10% or so of the plant was girdled. This immune response is seen in other species as well. An acute injury and a general response throughout the whole plant. I do not believe that cutting off the flow of nutrients back down to the roots is what is causing the growth increase. I believe it is the immune response and the plant/trees worried now is the time to reproduce or potentially never. Nature will never pick the never option. I will maybe upload pics soon.