News article

Mapping crop evaporation by measuring stem thickness

05 September 2023

Digitally controlled cultivation makes it possible to take more variables into account when managing the climate. For example, Priva’s research shows that a plant’s stem thickness is a good indicator of crop evaporation and therefore useful for controlling the climate. More good news: last season it was found that when using Plantonomy, a crop needs less energy for the same production and quality, according to Nienke Veenendaal at Priva.

Plantonomy is a new generation of crop management: it uses smart algorithms to control the plant’s water balance in a biorhythm. The crop has a daily rhythm of water intake and transpiration. Plantonomy uses a digital twin to autonomously regulate the climate and irrigation. Every five minutes it controls many of the climate settings for irrigation, ventilation, heating, screening and lighting of the greenhouse.

Plantonomy is now being used by several tomato and sweet pepper nurseries in North America as well as in the Netherlands. Nienke Veenendaal, Product Manager Plantonomy at Priva: “Demand for systems like Plantonomy is booming. By consolidating all kinds of separate controls into the essence of what is needed for a regular and strong crop, young growers in particular are able to achieve good production and quality much faster.”

Generative or vegetative

Last growing season, Plantonomy clearly demonstrated its value: it proved possible to achieve the same production and quality at a lower greenhouse temperature. In other words, less energy was needed to achieve the same results. “In addition, the crops and their roots were stronger: more resistant to changes in the weather, and there were fewer fungi and viruses, for example,” explains Nienke.

During cultivation, the sap flow and stem thickness were measured for the first time: sensors from 2Grow were attached to stems for this purpose. Nienke: “The stem thickness is a good indication of crop evaporation. For example, you could see that in the morning – when the crop is evaporating – the stem thickness decreased, and when water was being absorbed, the stem became thicker again.”

So, the stem thickness says a lot about the state of the crop, and the sap flow also says something about evaporation. “These variables show us when a crop is mainly growing generatively, and when it is mainly vegetatively. Furthermore, these measurements are objective. This prevents you from controlling the crop solely based on a feeling, and thus creating unrest.”

Measurements of stem thickness and sap flows are a particularly good tool for understanding, but due to the sensitivity of the measurement, they are not part of Plantonomy's direct crop control, according to Nienke. “A sensor around a stem is easily influenced by an employee touching it, for example. And robust measurements such as those of the outside radiation and a drain measurement have been proven in practice for years and are sufficient for stable control with Plantonomy.”

Accelerating Green Digitization of Greenhouse Horticulture

The research into sap flow and stem thickness when growing with Plantonomy is part of the project “Accelerating Green Digitization of Greenhouse Horticulture.” Multiple parties from the horticultural sector are working together to accelerate the application of digitization: Zentoo, Delphy, Greenport West-Holland (Innovatiepact [Innovation Pact]), Glastuinbouw Nederland, Inholland, Delphy Improvement Centre and Priva.

 By: Mario van Vliet

Foto Plantonomy Artikel Sapstroom En Stengeldikte