The Belgian horticultural research organisation Inagro has published an update on the Interreg PlantGoed project which focuses on optimising the cultivation of strawberry seedlings to meet the specific requirements of different cultivation systems.
As part of the project, a trial was recently completed with the variety Sonsation to evaluate the effect of darkening during cultivation on production performance. “The idea was to darken and force the plant to flower more quickly so that it could be packed earlier and the plant could still build up sufficient cold hours before planting in early December,” explained Inagro’s Simon Craeye.
Two darkening techniques were compared from 6 August: one where the daylength was reduced to ten hours and a second where the day only lasted seven hours. Flower bud examination under the microscope showed that darkening led to flower formation after just one week, while in the non-darkened planting material, flower formation did not start until 5 September. “Despite this month’s lead, we saw no significant difference in production last spring,” added Simon. “All treatments achieved a yield of 6 to 7kg/linear metre with a harvest starting in early March. Within this trial we also planted long-stored planting material from 2023. This resulted in clearly poorer fruit quality: only 58% Class 1 compared to 75% for the planting material from 2024, although it was notable that the old planting material came into production a week earlier”.
Greenhouse trials were also conducted with the everbearing varieties Karima and Florice, planted at the beginning of March, and have been in full production since April. Different types of planting material were grown in the greenhouse or in the daylight-free cultivation container and then potted without cooling, hence the name ‘fresh plant’. We compare the harvest progress and production potential with a classic cooled mini-tray plant.
“The beautiful spring weather is visibly doing this planting good,” said Simon. “The production of the fresh plants has been increasing steadily since the start. Since week 20 we have been picking a weekly yield of around 1.0kg/linear metre, with a total production of between 3 and 4.4kg/linear metre for the fresh Karima and Florice on 28 May, compared to 2.6 to 3.2 kg/linear metre for the cooled control planting material”.
He added that it is striking that the fresh plants still show plenty of red and green fruits and flowering, while production in the cooled objects seems to be slowly coming to a standstill. We are curious to see how many of our types of fresh plants will be able to achieve a sufficiently high and flat harvest progression. The fruit quality from the fresh plants was also reported as being good, with 80-92% Class 1 fruit, compared to only 75-80% Class 1 from the cooled plant material.
