The development of a specific concentration of cannabinoids is critical in the medical space of the cannabis industry. For this reason, research has also been focusing on how to drive the plant’s growth in such a way as to achieve the desired concentration of this or that cannabinoid. Bernstein et al. demonstrated that cannabinoids concentration can be affected by nutritional supplements, amongst other things. Of the most important nutrients, Nitrogen is one of the most understudied. That is why Bernstein et. al, in their new paper, further explores how nitrogen affects cannabinoid and terpene profiles in medical cannabis. The authors state that ‘current knowledge on the responses of cannabis to N input is not sufficient to direct regulation of secondary metabolism in the medical plant product’. So, they set up an experiment to assess the hypothesis that how different concentrations of nitrogen influences functional physiology and cannabinoids and terpenoids biosynthesis.
The experiment was conducted using the ‘Annapurna’ cultivar, which contains 7% of both THC and CBD. After one week of vegetative growth with long photoperiod, plants were treated with different concentrations of nitrogen and divided into five treatment groups. The N concentrations were 30, 80, 160, 240, and 340 mg L-1. Then, the short-photoperiod was implemented thus to stimulate inflorescence development.
At the end of the experiment, the authors noted that leaf color changed visibly from pale yellow to dark green with the increase in N supply. On top of that, the flower biomass and leaves increased by 206% and 103% respectively, in the 30-260 mg L-1 N supply. At the same time, the nitrogen use efficiency decreased dramatically with the higher supply of N. The concentration of all the acidic cannabinoids decreased as the N supply increased.
Thus, the authors claim that their results explain the importance of an adequate N supply for plant secondary metabolism. As pointed out, one of the findings shows that with the increase of N supply, there is a dramatic decrease in cannabinoid and terpenoid concentration, while the plant growth and physiological status improved. Cannabis plants suffered from N deficiency when the supply was lower than 150 mg L-1. Similarly, most of the parameters, such as photosynthetic rate, water use efficiency etc., were lower when the N supply was lower than 160 mg L-1.
Given all the data they collected, the authors deduce that “160 mg L− 1 N is a sufficient concentration for maximal yield and higher N supply did not reduce yield. Taken together with the negative impacts obtained for high N supply on secondary metabolite accumulation, we suggest that the optimal level for excelled yield quantity, as well as quality, i.e., high secondary metabolites profile, is 160 mg L− 1 N.”
Source: sciencedirect.com