Till this day the production of high wired cucumbers in the WUR’s winter light greenhouse, that has 10% more light than a regular greenhouse, is doing fine. On the 28th of June, a total of 148 fruits and 65 kg/m2 with a fruit weight of 440 grams has been harvested. Once again this is higher than some of the best companies in this practice, which has reignited the discussion of how this is possible. Are we perhaps taking too much care of the crops in our greenhouses? This is what is being questioned of Jan Janse and Frank Kempkes of the WUR.
More light
Just like last year, there is a research supervising committee (BCO) discussion about the high productions achieved by Wageningen University & Research, Business Unit Glastuinbouw in Bleiswijk. 10% more light also means more production for cucumbers, but to save energy in the first few months the crops are protected during the day. This requires additional light and results in less assimilation production. Also, the greenhouse does not contain a high level of CO2: the maximum dosage capacity is 100 kg/ha/hour.
BCO discussions about crop care
A reoccurring factor in the discussions is crop care. Everyone is convinced that good crop care can be seen as an important factor in the high productions. It is good to realize that in a year-round cultivation like we do this year, every stem has had a treatment of the rings, fruit thinning, leaf cutting and harvesting. The chance of something not working out in the best way possible during some of these treatments is unavoidable. According to us the fruit thinning is an important factor. Do you remove the fruit of very sick plants or do the opposite. To gather reliable data it is important that the care given in the tests is done in similar ways, so there needs to be work carried out precisely. This we try to do in all treatments and during harvest. It can be quite useful to see if giving more attention to crop care, with a rise in production as consequence, can be profitable. Let’s say we get a 5% increase in product, then even with some extra labor it could still be profitable.
Pushing the boundaries
Obviously, in the tests, they push the boundaries of what is possible. For instance, during the reference treatment starting at the beginning of May (week 18), we let a set of two fruits in a row stay on the stem every week. We also have a treatment with extra stems (4.2 stems/m2 and we alternate the thinning) and a treatment where we leave sets of two fruits every time. For now, there is not much of a production difference, but the season is still long and in references, every extra week fruits are being retained. With autumn approaching we will, of course, take into account the amount light and reduce the number of stems and fruits retained.
Obviously, in the tests, they push the boundaries of what is possible. For instance, during the reference treatment starting at the beginning of May (week 18), we let a set of two fruits in a row stay on the stem every week. We also have a treatment with extra stems (4.2 stems/m2 and we alternate the thinning) and a treatment where we leave sets of two fruits every time. For now, there is not much of a production difference, but the season is still long and in references, every extra week fruits are being retained. With autumn approaching we will, of course, take into account the amount light and reduce the number of stems and fruits retained.
One single long cultivation process
The idea is to continue with the same plants till mid-November. It will be one single long cultivation, that’s why the stems have been re-rooted two times. For this, specially developed Re-Root trays have been used for the re-rooting and have been filled with coco. After four days new roots were visible in the leaf axils, but the dying of the first stem parts has not been observed yet. This part with roots is therefore still functioning. Also when re-rooting we say ‘work precisely’, because if we don’t the results will be a disappointment.
The idea is to continue with the same plants till mid-November. It will be one single long cultivation, that’s why the stems have been re-rooted two times. For this, specially developed Re-Root trays have been used for the re-rooting and have been filled with coco. After four days new roots were visible in the leaf axils, but the dying of the first stem parts has not been observed yet. This part with roots is therefore still functioning. Also when re-rooting we say ‘work precisely’, because if we don’t the results will be a disappointment.
Read more about this project here.
Source: Kas als Energiebron