Expansion and Improvement for Multi-layer Strawberry Cultivation
by Groentennieuws15 May 20255 min read
Tholen - The trial for multi-layer strawberry cultivation at the Hoogstraten Test Centre is expanding. Currently, the final winter crop is being harvested. After this, researchers will work on the exact setup of the next trial. It is certain that instead of 6, there will be 18 rows of 3 or 4 layers. The final decision on the number of layers has yet to be made.
Since 2019, the distinctive cultivation setup has been present in the greenhouse complex. From the road next to the complex, the brightly pink LED-lit 'stack' of strawberry gutters is clearly visible at the end of January. This winter, researchers are harvesting the Sonata variety from a crop planted in October. It is a true winter crop, following earlier trials with all conventional crops using June bearers under glass in spring, summer, autumn, winter, and autumn again with continuous cultivation. Ever bearers have not yet been tested in this system.
"Out of all the different cultivations, we've learned that a true winter crop works best under LED, due to the maximum controllability we have with LED lighting in such a cultivaton," explains Stef Laurijssen. "Certain periods are more suited for multi-layer cultivation as we are doing here. When there is a lot of natural light, we see that the lower layers perform less well, with issues like fruit deformation occurring."
Lighting
During the initial phase of the multi-layer cultivation system trial, it was quite challenging to find the appropriate LED lighting. However, the researchers have now successfully addressed this issue. The trial is now divided into two sections. One section is equipped with Luminaid fixtures, providing up to 300 micromol/(m2.s), while the other section has MechaTronix fixtures, providing up to 340 micromol/(m2.s). Both types of fixtures are dimmable.
"The spectra for both sections are almost identical," notes Stef. The Luminaid fixtures have an added far-red LED strip, whereas far-red is already included in the MechaTronix spectrum. Another difference is the beam angle. "The beam angle is larger with MechaTronix at 120 degrees. Luminaid fixtures have a beam angle of 90 degrees. The advantage of the larger beam angle is that it illuminates the fruits of the adjacent row as well, which helps with color development."
RH Remains a Challenge
By the end of January, the color development is looking good. Especially in the rows that haven't been harvested yet, there are many ripe red strawberries. Perhaps even too many, admits Stef while colleagues are busy harvesting.
As we step onto the tube rail lift and move up between the gutters, we encounter two vertical fans at the top. "An experiment," Stef explains. "We had these fans left over from another greenhouse section and wondered if they might be useful here. Unfortunately, they are not suitable, as the plants on the top row suffer too much from the air movement."
The vertical fans are used to reduce the relative humidity (RH) at the bottom of the system. A challenge in multi-layer cultivation is the increase in RH at the bottom, which can lead to fruit rot. "Last growing season, we worked with vertical fans and an air tube. We made holes in the tube at the level of the rows and tied off the bottom. You don't do this in a horizontal application, but this way we managed to create a more homogeneous climate across the different rows."
Optimal Lighting
One noticeable detail is the presence of tags with numbers hanging everywhere. The gutters have been divided into sections by the researchers, who are testing various cultivation strategies during the current winter crop. The goal? To investigate how best to achieve energy savings.
A winter crop of Sonata planted in October requires a total light sum of 1900 mol/m2. Using a lighting table, this light sum is distributed over the different stages of cultivation, up to a maximum of 18 mol per square meter per day when the plant is in full production. The researchers also consider the influx of natural light.
In the system with 4 layers, light penetration decreases rapidly. By the second layer, only 35% of the light remains. "Initially, we thought it was 50%, but we quickly discovered, after measuring, that it was even less." For the third layer, only 10% remains, and for the fourth layer, only 5%. For this reason, the researchers choose to use more light on the lower rows.
Strategies for Energy Savings
In their research on energy savings, the researchers are testing various strategies this winter as part of the Opti-Energy project (VLAIO LA-traject). During the most expensive hours for electricity, typically between 7-11 AM and 5-7 PM, part of the cultivation setup's lighting is turned off. "We are investigating how this cost-saving measure affects plant growth." Another strategy is to reduce the total light sum from the maximum of 1900 mol/m2 to 1800 or even 1600. Finally, they are also looking into reducing the number of lighting hours per day. Is it feasible to light for 14 hours instead of the usual 16 hours?
After this ongoing winter crop, the researchers will be able to share results. In the next phase of the multi-layer cultivation trial starting at the end of 2024, the researchers are considering using active dehumidification. The plan is to start a new cultivation round in an expanded setup in 2025.
Another development by that time is the creation of a section at the research center for growing strawberry starting material without daylight. "For this purpose, we will line a section of a greenhouse with sandwich panels," Stef explains.
Additionally, an expansion is underway. During our visit to the research center in Meerle, an old greenhouse had just been demolished. In its place, a new 1.4-hectare greenhouse will be built. Through co-creation sessions, the researchers are still discussing the exact design of this new greenhouse with growers and technology partners. "We hope to plant strawberries in this new greenhouse by mid-August."
Read More>>https://www.horti-growlight.com/en-gb/expansion-improvement-multi-layer-strawberry-cultivation
"Out of all the different cultivations, we've learned that a true winter crop works best under LED, due to the maximum controllability we have with LED lighting in such a cultivaton," explains Stef Laurijssen. "Certain periods are more suited for multi-layer cultivation as we are doing here. When there is a lot of natural light, we see that the lower layers perform less well, with issues like fruit deformation occurring."
Lighting
During the initial phase of the multi-layer cultivation system trial, it was quite challenging to find the appropriate LED lighting. However, the researchers have now successfully addressed this issue. The trial is now divided into two sections. One section is equipped with Luminaid fixtures, providing up to 300 micromol/(m2.s), while the other section has MechaTronix fixtures, providing up to 340 micromol/(m2.s). Both types of fixtures are dimmable.
"The spectra for both sections are almost identical," notes Stef. The Luminaid fixtures have an added far-red LED strip, whereas far-red is already included in the MechaTronix spectrum. Another difference is the beam angle. "The beam angle is larger with MechaTronix at 120 degrees. Luminaid fixtures have a beam angle of 90 degrees. The advantage of the larger beam angle is that it illuminates the fruits of the adjacent row as well, which helps with color development."
RH Remains a Challenge
By the end of January, the color development is looking good. Especially in the rows that haven't been harvested yet, there are many ripe red strawberries. Perhaps even too many, admits Stef while colleagues are busy harvesting.
As we step onto the tube rail lift and move up between the gutters, we encounter two vertical fans at the top. "An experiment," Stef explains. "We had these fans left over from another greenhouse section and wondered if they might be useful here. Unfortunately, they are not suitable, as the plants on the top row suffer too much from the air movement."
The vertical fans are used to reduce the relative humidity (RH) at the bottom of the system. A challenge in multi-layer cultivation is the increase in RH at the bottom, which can lead to fruit rot. "Last growing season, we worked with vertical fans and an air tube. We made holes in the tube at the level of the rows and tied off the bottom. You don't do this in a horizontal application, but this way we managed to create a more homogeneous climate across the different rows."
Optimal Lighting
One noticeable detail is the presence of tags with numbers hanging everywhere. The gutters have been divided into sections by the researchers, who are testing various cultivation strategies during the current winter crop. The goal? To investigate how best to achieve energy savings.
A winter crop of Sonata planted in October requires a total light sum of 1900 mol/m2. Using a lighting table, this light sum is distributed over the different stages of cultivation, up to a maximum of 18 mol per square meter per day when the plant is in full production. The researchers also consider the influx of natural light.
In the system with 4 layers, light penetration decreases rapidly. By the second layer, only 35% of the light remains. "Initially, we thought it was 50%, but we quickly discovered, after measuring, that it was even less." For the third layer, only 10% remains, and for the fourth layer, only 5%. For this reason, the researchers choose to use more light on the lower rows.
Strategies for Energy Savings
In their research on energy savings, the researchers are testing various strategies this winter as part of the Opti-Energy project (VLAIO LA-traject). During the most expensive hours for electricity, typically between 7-11 AM and 5-7 PM, part of the cultivation setup's lighting is turned off. "We are investigating how this cost-saving measure affects plant growth." Another strategy is to reduce the total light sum from the maximum of 1900 mol/m2 to 1800 or even 1600. Finally, they are also looking into reducing the number of lighting hours per day. Is it feasible to light for 14 hours instead of the usual 16 hours?
After this ongoing winter crop, the researchers will be able to share results. In the next phase of the multi-layer cultivation trial starting at the end of 2024, the researchers are considering using active dehumidification. The plan is to start a new cultivation round in an expanded setup in 2025.
Another development by that time is the creation of a section at the research center for growing strawberry starting material without daylight. "For this purpose, we will line a section of a greenhouse with sandwich panels," Stef explains.
Additionally, an expansion is underway. During our visit to the research center in Meerle, an old greenhouse had just been demolished. In its place, a new 1.4-hectare greenhouse will be built. Through co-creation sessions, the researchers are still discussing the exact design of this new greenhouse with growers and technology partners. "We hope to plant strawberries in this new greenhouse by mid-August."
Read More>>https://www.horti-growlight.com/en-gb/expansion-improvement-multi-layer-strawberry-cultivation