AmWeedwolf
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An exciting new study has been published by Frontiers in Plant Science on the effect of phosphorus supply on medical cannabis flower yield, cannabinoid content, and plant morphology.
Before I get into the results, I want to note that P (phosphorus) concentrations are different from phosphate (P2O5) concentrations listed as NPK numbers on fertilizer labels. To determine phosphate levels multiply P by 2.29. For example, 30 ppm P = 68.7 ppm P2O5
Its main findings were:
My takeaway is that these results appear to be somewhat preliminary and are genotype-specific and relevant only to hydroponic systems under artificial lights with highly controlled environmental conditions. Additional research is needed to see if the observed effects ring true for other (similar) strains in this system. Additional research is also needed to explore the effects of P availability in systems with less uniform (organic, living soil) and/or sub-optimal (greenhouse/outdoor) environmental conditions, especially regarding the interaction of P availability and mycorrhizae colonization and the resistance to fungal pathogens this confers.
But it's a very interesting new data point on the debate about Phosphorus requirements in Cannabis cultivation!
Before I get into the results, I want to note that P (phosphorus) concentrations are different from phosphate (P2O5) concentrations listed as NPK numbers on fertilizer labels. To determine phosphate levels multiply P by 2.29. For example, 30 ppm P = 68.7 ppm P2O5
Its main findings were:
- P levels between 30-90 ppm were within the optimal range for plant development and function sufficient for achieving maximum yield.
- P levels of 30 ppm achieved maximum flower yields in the high THC/low CBD strain 'Royal Medic' while p levels of 90 ppm achieved maximum flower yield in the balanced THC/CBD strain 'Desert Queen'. However, the opposite was found for total cannabinoid yield per plant; 30 ppm P achieved max cannabinoid yields for the balanced THC/CBD strain, while 90 ppm P was needed to achieve maximum cannabinoid yield in the high THC/low CBD strain.
- P supply above 5 ppm lowered cannabinoid levels by up to 25% and were highest <30 ppm for both strains
My takeaway is that these results appear to be somewhat preliminary and are genotype-specific and relevant only to hydroponic systems under artificial lights with highly controlled environmental conditions. Additional research is needed to see if the observed effects ring true for other (similar) strains in this system. Additional research is also needed to explore the effects of P availability in systems with less uniform (organic, living soil) and/or sub-optimal (greenhouse/outdoor) environmental conditions, especially regarding the interaction of P availability and mycorrhizae colonization and the resistance to fungal pathogens this confers.
But it's a very interesting new data point on the debate about Phosphorus requirements in Cannabis cultivation!