Factoring photomorphogenesis
into your lighting strategy

When deciding which type of lighting to invest in at your facility, for example, factoring photomorphogenesis into your thought process can go a long way toward informing that decision. How plants respond to the light spectrum at different phases of their life cycle is the simple definition of photomorphogenesis in plants. Different from photosynthesis – which is the process through which plants convert light into food – photomorphogenesis in plants is more about the individual morphological responses to light. In an indoor operation where lights stand in for the sun, a greater understanding of plant photomorphogenesis can tell growers a lot about the impact different spectrum balances have on growth phases. So when it comes to assessing your approach to lighting, here’s how the photomorphogenesis of the cannabis plant comes into play.

Plant photomorphogenesis overview: how different light spectrums impact growth

A vital source of energy for plants, light is the catalyst behind the production of carbohydrates necessary for everything from seed production to photosynthesis. Light is comprised of a spectrum of colors ranging from blue to red, and within each of those colors lies the ability to initiate a response in the plant’s development – the basis of plant photomorphogenesis. 

At the blue end of the spectrum, a protein known as phototropin supports photosynthesis by optimizing such functions as stomatal opening and leaf expansion. In the middle of the spectrum, green-detecting cryptochrome photoreceptors help regulate things like leaf growth and the plants’ circadian rhythms. Then on the red/far-red end of the spectrum, phytochrome is the protein that nurtures photomorphogenesis along though leaf expansion and stem elongation.

For growers who integrate crop steering techniques into their cultivation practices, this information can be incredibly useful. When trying to steer vegetatively, for example, enabling more blue ratios helps increase stalk and stem growth. When it’s time for ripening, generative steering benefits more from the red/far-red side of the spectrum. When determining the optimal lighting for your facility – e.g., choosing between HPSs versus LEDs, seasonal settings such as light functionality, manufacturer, and more – keeping photomorphogenesis in mind can help cultivators hone in on what makes the most sense for the outcomes they’re looking to achieve with each phase of the plant’s life cycle.

Using AROYA to track and monitor photomorphogenesis

At the end of the day, figuring out the perfect spectrum for each phase of plant growth is less about a specific make or model, and more about using crop registration to track and monitor how your crops respond to the lights you already have. Using AROYA to document how each cultivar responds to the different spectrum colors, and for how long, then reviewing it at the end of a run as historical data gives growers the exact intel they need to be able to reproduce those results again and again. Check out Jason’s deep dive into photomorphogenesis from Office Hours Episode 51.

Related reading: How to Choose LED Lights for Cannabis Cultivation

Sources:

Takemiya A, Inoue S, Doi M, Kinoshita T, Shimazaki K. Phototropins Promote Plant Growth in Response to Blue Light in Low Light Environments. Plant Cell. 2005 Apr;17(4):1120-7. doi: 10.1105/tpc.104.030049. Epub 2005 Mar 4. PMID: 15749755; PMCID: PMC1087990.

Lin C, Todo T. The crytochromes. Genome Biol. 2005;6(5):220. doi: 10.1186/gb-2005-6-5-220. Epub 2005 Apr 29. PMID: 15892880; PMCID: PMC1175950.

Li J, Li G, Wang H, Wang Deng X. Phytochrome signaling mechanisms. Arabidopsis Book. 2011;9:e0148. doi: 10.1199/tab.0148. Epub 2011 Aug 29. PMID: 22303272; PMCID: PMC3268501.