Light recipe research in the Netherlands


#1

Today I came across this interview with Dr. Celine Nicole who is a research scientist at Philips (GrowWise research center). The interview is about the talk she will be giving in June on “Light recipes enable sky high vitamins and a longer shelf life in leafy greens” at the Vertical Farming Conference in The Netherlands.

The interview doesn’t have any technical details, but it does talk about how Philips is building a database of light recipes for doing things like boosting vitamin C and vitamin K in greens. There was also a mention of collaboration with professor Leo Marcelis at Wageningen University.

This is interesting to me because I wonder if they have publicly published any of their light recipe research. Maybe someone here would like to search for papers about this research and post links. Also, it’s good for people here to be aware that OpenAg is just one of many groups interested in light recipes.


#2

cool. on a related note: How would someone like us record our own light recipes from our environment? What sensors would be appropriate and how often would/should one record data?

I would like to first record the “recipe” for my own outdoor environment before attempting to tweak it. I just have no idea how i could go about that.


#3

I’d suggest looking in a different direction. If you study the physics of light and weather, you can potentially model any climate you want. On the flip-side, if you don’t understand the physics, there’s not much point in deploying sensors. If they gave you a number, what would it mean?

Useful topics:

  1. Calculating the position of the sun: How do you calculate day length from latitude and date? How would you adjust this for a mountain valley, foothills along the front range, or a hillside facing the sea?

  2. Scattering and absorption of light in the Earth’s atmosphere: What makes the sunset red? Why is the sky blue? What factors contribute to variations (dust, humidity, temperature, etc.)? How much does UV vary with elevation? How can you quantify that stuff with formulas or tables?

  3. Microclimates: What changes based on elevation, north or south facing slopes, daily temperature swings, light pollution, etc.?

  4. Meteorologic records: How do you look up average days of sunshine each year for a city in the US or elsewhere? What’s the difference in DLI between a sunny and cloudy day?

  5. Daily Light Integrals (DLI): University CEA departments like Cornell, Arizona, etc. publish papers about daily light integrals. Floriculture departments like MSU may have even more about long-day plants, short-day plants, and mixing ratios of wavelengths to control flowering.

  6. For crops you care about, where and when have they been known to grow very well? What records can you find for the climate at that time and place? For any missing pieces of that data, what can you calculate or estimate?

I mention these questions because I’ve been wondering about them. Some of them have a “well, duh… it’s because [some conventional wisdom explanation].” But, it gets tricky when you try to calculate numbers. Like how blue is blue, and how red is red? I’ve watched the sky. It depends on humidity. It depends on whether there’s a forest fire upwind. It depends on pollution. Presumably there are other factors.

At some point, the interesting part comes from botany–what are the thresholds that trigger the photobiological processes you care about? This might be interesting to think about in relation to the boundaries of the USDA plant hardiness zone map.


#4

that is an interesting thought. But i was thinking starting small. Like a lux sensor for example. Take it outside and record the daily high and daily low value, and do this for your outdoor growing season in your area and at your elevation. What would that data mean? Well by itself perhaps nothing, but you could try to match that data to your own indoor lights to replicate it as close as possible. Yes forest fires and cloudy and rainy days would interfere, but i would think you could get a general trend that plants would still be happy with. Even better if you had a humidity and rain sensor to record how often to water and how much. The same could apply to other sensors like UV, etc.


#5

Lux sensor wouldn’t be very helpful in regards to understanding what plants need. Lux is what human eyes perceive. For plants, you want to use a PAR sensor, which gives you the spectrum that plants perceive. Use a PAR meter to measure the spectrum at your growing site, in addition, record the PPFD value at your plant’s canopy or at your plant’s ground level. The PPFD and spectrum will change drastically during a day depending on the position of the sun, so be sure to measure several times a day. Those data should give you the necessary information for your light recipe.

Since the spectrum of sunlight is very broad, you only want to look at the suggested PAR range for plants, and that spectrum information is what you possibly want to replicate in an indoor environment through LEDs.

Further more for environmental information, using humidity sensor alone is enough, no need to over do it since the information that you collect in the end overlaps.


#6

Go for it. See what happens.

If you want to learn more about human perception of color, lux vs. lumens, the luminous efficiency function, etc., here are some useful links: