Lighting is one of the major elements of any indoor or greenhouse cannabis cultivation. Research has been done to further understand how light can drive the development of specific properties of cannabis plants, as this is critically relevant for growers who need plants to develop more in certain ways. Recently, several universities and companies have explored the intricacies of light-cannabis interaction, making very interesting discoveries and paving the way for more interesting insights. In a paper published on Industrial Crops and Products authored by Nadav Danziger and Nirit Bernstein, the hypothesis that plant growth and secondary metabolism is intensified under a full spectrum with similar Blue: Red ratio.
Light intensity, quality, and photoperiod
The main elements of light that influence plants are light intensity, light quality, and the photoperiod. The authors note that the medical cannabis plant produces large amounts of secondary metabolites, which require a lot of energy. Thus, it is critical to better understand how photosynthesis reacts to the light spectrum and thus how energy balance and secondary metabolism function in the plant.
Through an experiment, the authors noticed a metabolite-specific response to light spectra: specifically, they saw an increase of up to 400% of CBGA under LED lights compare to HPS; at the same time, other primary cannabinoids such as THCA, CDBA, or CBCA decreased under LEDs.
Additionally, they indeed noticed that light spectra influenced the morphological development and physiological function of the plant. For instance, blue light increased stomatal conductance and development, and photoperiod flowering, and circadian clock regulation. On the other hand, a high percentage of red light made plants longer, suggesting that a lack of blue light can indeed be the cause of elongation in cannabis.
Moving forward
Research is still ongoing, and there are still a lot of things to further understand. The authors of the paper indeed point out that their results do signal that light spectrum can manipulate the cannabinoid profile of a given plant. In another recent research conducted by Fluence and the Wageningen University, they have indeed noticed how red light can be used to manipulate terpene ratios in cannabis. On top of that, a low percentage of red light caused an increase in cannabinoid concentration.
Thus, it is of the utmost importance to advance the research in this field as a better understanding of how cannabis growth can be manipulated by light spectra would allow growers to maximize the efficiency of their operation by ensuring that plants would express their full genetic potential.