In the AGROS project we are working towards an autonomous greenhouse in which cultivation is controlled remotely by intelligent algorithms based on automated measurements with sensors. After a successful validation trial in early 2023 in which cucumbers were grown autonomously, the concept was broadened to the other model crop of the project, chrysanthemum. Current challenges in chrysanthemum cultivation are the high energy consumption for steaming of the soil to prevent soil-borne diseases and the requirements regarding the prevention of emission of nutrients. These challenges were addressed in a trial at the business unit Greenhouse Horticulture of Wageningen University & Research where chrysanthemums were grown in containers with a soil mixture.
Process of the trial
In this trial, two chrysanthemum varieties were grown under two irrigation strategies, which were ‘sufficient irrigation’ and ‘limited irrigation (75%)’. During cultivation, a number of plant and substrate sensors were used to for continuous and automated measurements of plant weight, water uptake, transpiration and drain. Soil water content sensors proved to be very effective in controlling the irrigation strategy by keeping constant levels of soil moisture in the two treatments.
Working towards an autonomous control in chrysanthemum cultivation
Subsequent percentages of drain were approximately 15% in the sufficient irrigation treatment, and no drain in the limited irrigation treatment. Crop transpiration was calculated based on plant temperature measurements and climate data. These data corresponded well with plant weight measurements, and showed a clear difference in transpiration between the irrigation strategies. However, this did not affect stem length and stem weight of the harvested chrysanthemum flowers. This indicates that irrigation can be reduced without adverse effects on the crop, and that control via crop and substate sensors is very well possible, opening up to autonomous control in chrysanthemum cultivation.