Proefcentrum Hoogstraten has been cultivating strawberries on hoistable gutters for several years now. 2023 turned out to be an 'exceptional year'. The yield of the everbearing variety Karima was greater than in previous years. At the Strawberry Day, researcher Peter Melis said that the reasons for this 'exceptional year' remain somewhat uncertain. Nevertheless, after several years of testing, they are now confident about the system's potential.
© Proefcentrum HoogstratenTest with hoistable gutters at Proefcentrum Hoogstraten in 2023
In 2018, Proefcentrum Hoogstraten equipped a polytunnel with a special system developed by Metazet (formerly Metazet-FormFlex). In this greenhouse of the Van Den Heuvelserre type, they cultivate everbearing strawberry varieties, which have been attracting growing interest since 2015.
The crop was first cultivated in this greenhouse in 2019. Last year, the new everbearing variety Karima was tested for the first time. After two challenging years for everbearing strawberries in 2021 and 2022, the results in 2023 were exceptional. Matching the production of 2023 won't be easy, according to Peter.
Yield when hoisting
Making use of the special setup in this greenhouse, the researchers primarily focus on optimizing yield by adjusting row spacing. 8 gutters in a 9.6-meter span were compared with 10 and 12 gutters. This more efficient use of the cultivation space is possible thanks to the hoistable system. The hoisting is done electronically, making smart use of the weight of the gutters. When the even gutters descend, the odd gutters rise, and vice versa.
Peter Melis' presentation at Strawberry Day 2024
Shadowing
The researchers noticed that more production loss occurs when the gutters are hoisted compared to when they are placed closer together. The reason? Shadowing. "Our advice is to keep the gutters as level as possible." Therefore, hoisting should be minimized, as it takes time (about 8 to 9 minutes to get one gutter up and the other down) and results in a loss of light. "For the same reason, we try to perform as many tasks simultaneously. For example, crop work during the harvesting."
Limits to reduction of row spacing
The highest yield was achieved with 12 gutters per span, and researchers do not recommend adding more gutters. "Then you run the risk of the branches getting tangled." With 80 centimeters between the gutters and 12 gutters in a 9.6-meter span, a grower can cultivate 50 percent more plants on the same surface. "That is a substantial expansion," says Peter. In 2023, this resulted in a 28 percent increase in production per square meter.
Test on hoistable gutters at Proefcentrum Hoogstraten
Higher costs, higher yield
What did the Karima production amount to in 2023? Over 6 months (harvest between May 23 and September 27), 2.43 kilograms per plant were harvested with a row spacing of 1.2 meters. With 0.96 meters of row spacing, the volume stood at 2.15 kilograms, and with 0.8 meters, at 2.08 kilograms per plant. The reason for this lower production is, as mentioned, shadowing.
At Strawberry Day, Peter compared the figures from the exceptional year 2023 with the costs. The yield per square meter increases as the grower reduces the row spacing. In 2023, Karima crops yielded a return of 26.54 euros per square meter (compared to 22.64 euros at 1.20 meters row spacing). The costs also increased, but the extra kilos made up for that.
Yield figures from the 2023 test with the Karima variety
In Meerle, after several years of testing, they strongly believe that a production of 15.56 kilograms of strawberries per square meter in 6 months (the yield in 2023) shows that boundaries can be pushed with everbearing varieties like the Karima using a hoistable gutter system. Even if an exceptional year like 2023 cannot be easily surpassed,
Photos from the 2023 test and table courtesy of Proefcentrum Hoogstraten
For more information:
Peter Melis
Proefcentrum Hoogstraten
peter.melis@proefcentrum.be
www.proefcentrum.be