Digitizing your cultivation. That is something growers cannot avoid. But how to get started? During his introduction at the Delphy, Glastuinbouw Nederland, Greenport West-Holland, Zentoo, Inholland, and Priva Digitalization Event, Woody Maijers of Greenport West-Holland cited that there are countless ways to do so. "Remember, what was impossible yesterday may be possible today. When is the right time for you to begin with this development?" he asks.
At Tuesday's event, practical tools were offered to vegetable and ornamental plant growers. Guests could choose three topics from 12 workshops. The presentations covered various topics, like available sensors and their uses, climate tools, and digitalization combined with sustainability and cybersecurity.
One of those workshops was about measuring photosynthesis. Sendot's Arie Draaijer and Delphy's Alex van Klink presented this session. Above and below-ground factors affect the sensors and their measurements. Think of wind, CO2, EC, and Ph as some of these variable factors. The goal is, thus, to get results as quickly as possible.
A sensor's general purpose is to monitor fruit growth. Photosynthesis drives that. When that is not at its best, the plant can be damaged. When photosynthesis is subpar, under artificial light, energy is wasted. Measuring photosynthesis gives insight into the light levels under which plants can convert energy effectively.
When light hits a plant, three things happen:
- Photosynthesis: Light is converted to sugars. That triggers growth.
- Chlorophyll fluorescence: When most of the photons are used for photosynthesis, it leaves little fluorescence. The other way around works the same way: fluorescence is present when a small proportion of the photons are used for photosynthesis.
- Heat: Delphy uses two sensors to measure photosynthesis - one from Sendot, clipped onto the topmost leaf, monitors par at that level. The one is from Crop Observer and hangs at the top of the greenhouse, measuring a different leaf each time.
Alex brought along a Phalaenopsis for testing. The sensor was attached to the leaf, and a flashlight was used to introduce different light intensities. The graph responded immediately. The photosynthesis efficiency was directly translated into ETR (Electron Transfer Rate).
It is calculated as follows; factor x par x efficiency. ETR does not account for generative/vegetative crops, photorespiration degree, or adaptation processes. It does, however, take into account forces such as light, gas exchange, and temperature.
What stood out was that there is a maximum to which light affects photosynthesis. One of the growers present attested to that. His greenhouse sensors measured that same effect. He saw that he did not need to light his Phalaenopsis crop for the standard 16 hours. Fourteen was measurably sufficient to produce photosynthesis to grow a good product. For this farm, therefore, 14 hours of exposure is optimal.
Here is an impression of the event via a photo report.
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