The past few weeks, the cultivation container at Inagro in Beitem (Belgium) was occupied by Sonsation and Sonata plants that are already raised before winter cultivation starts. If they were planted in mid-October, it wouldn't be possible to grow them outside during the same year. Namely, in summer conditions they wouldn't flower. The cultivation container allows for the simulation of different seasons regardless of the outdoor climate.During lit winter cultivation, Iterrreg will compare "fresh" plants from the container with 10-month-old refrigerated planting material (plants that were outside on the tray field last year and packed in December 2023).
Different phases
The raising of plants took place in several phases to ensure the most focused and optimal development of the June bearers.
Phase 1: Rooting
Once the cuttings are placed into the substrate, they are encouraged to root in. Without roots, they are very susceptible to dehydration during the first few days. A sufficiently high RH is achieved by fogging or covering with foil.
Phase 2: the Vegetative phase
Once rooted, the cuttings should develop into sturdy plants. A vigorous summer climate with long days leads to rapid growth and production of new leaves.
Phase 3: the generative phase
June-bearers only initiate flowers when day length becomes shorter (on the tray field from the beginning of September). Without flowers, clusters do not emerge in the production phase and cannot be picked. For this reason, the container short-day conditions and early autumn during this third phase.
Phase four: Hardening
Once the plants have enough flowers, and reached the desired stage of development, the tray plants are gradually cooled to prepare them for cold storage at -1°C. To ensure sufficiently deep cooling (up to 7°C), the plants move from the cultivation container to a refrigerated room equipped for this purpose.
Sonsation
Using lit cultivation containers is not the only method that can bring about June-bearers with early flower turn-over. Another way to let the plant experience short-day conditions is to artificially darken the growing environment.
- In greenhouses, blackout screens can be used.
- In the tray field, foils can be used over the plants.
For spring cultivation that will start in early December in the greenhouse, there was a need for Sonsation plants that have flowered early and that are ready by mid-October. This allows them to still go through their minimum required number of cold hours (six weeks).
In early June, Sonsation was grown on Inagro's tray field with the aim of testing the effect of three darkening methods on flowering. The comparison will be made with planting material that has been in the fridge since December 2023; plants that can be expected to gradually run out of reserves. Eclipse is not yet a standard practice, but has potential if it performs at least as well as the long-chilled plants. The economic added value of darkening is that long refrigerated storage can be avoided, potentially leading to greater yields and a more vigorous plant.
Lighting has little effect on rooting, but affects flowering
The cultivation container at Beitem has an ebb-and-flow system to irrigate the plants. This is different from the tray field where the plants are watered by means of overhead irrigation. In previous trials, it was found that indoor rooting was more difficult and that cuttings often dried out. As a solution, the cuttings were covered with a foil during the first week to ensure high humidity which limits evaporation.
In addition, it was learned that certain light would also stimulate rooting. Therefore, in June,Interreg investigated whether different light intensities and spectra could speed up rooting. For the time being, the trial did not produce a light recipe that achieved a strong root system faster. However, it was noticed that flowering differed greatly between treatments. The effect of different lighting strategies on flowering control in fresh eyesores will therefore also be tested in the coming weeks.
Source: Interreg