In both the demo greenhouse and the demo fields at Nunhems, the BASF vegetable seed branch, there is a lot of attention for lettuce. Especially during the open days in 's-Gravenzande in week 39. This will also be the case in the coming years with a continuously growing lettuce team. For example, this year the high-tech lettuce team was expanded with Jochim Reybrouck. In addition to the Belgian market, he will further expand his activities to northwest Europe.
One of the developments he will be working on is the development of good varieties for high-density hydroponic cultivation, in other words, the planting of lettuce as close as possible to each other. Jochim: "The question is how far you can go planting this close to each other without sacrificing quality. You don't just want nicely erected leaves with a good uniformity in length, but also retain a good leaf structure. From the processing industry there is increasing interest in this cultivation, in which you work towards a uniform crop that is easy to harvest."
High density hydroponic cultivation
In the baby leaf segment, Greenflash is one of the Nunhems varieties that is tested. It is a fresh green variety with very uniform 3D leaves and a good bite for a good fill of the bag. In addition to research into the effects of a high plant density on lettuce, but also on spinach, the development of varieties with a crispy bite is another focal point for the coming years. "A pleasant experience when eating a salad by combining colors and different types of leaf textures is becoming more and more crucial for the consumer. A slightly harder leaf takes care of that bite, but also for a good shelf life, also when packaged."
The Danstar variety with a crispy bite
In the greenhouse the lettuce is cultivated on water, in many different colors and varieties. The vegetable seed breeder is also bringing these different colors and varieties together by growing them as trios. The focus here is mainly on the multi-leaf segment. This cultivation is about color, the balance between the three varieties and also about a good, compact growth. "It is important that also with this kind of growing method there is minimal yellow leaf at the bottom of the heads, which saves labor. In standard combinations there often are two red colors with a blond type, but alternative combinations of red-green-blonde or combinations with a crispy variety are also increasingly being sold."
The coming winter, BASF will be introducing a new, vigorously growing multi-color mix that makes weight faster, specially for the winter. On the photo Jochim Reybrouck (left) and Peter Does, together they form the high-tech lettuce team.
The open field demo days are also coming up, with many Nunhems lettuce varieties. The same themes are also discussed here, as Stefan Hermans, lettuce specialist for the open field, explains. "This year we also started in the open field with planting and sowing at high density. The end product would then be able to be mowed mechanically. The crucial point is that we think we can save labor this way in the future. There is a lot of interest in this from the processing industry in the Netherlands, while the fresh market, certainly in Germany, still opts for heads of lettuce for the vast majority. Nevertheless, in the longer term, different varieties that are currently being tested might replace the romana lettuce or iceberg lettuce, but it is equally possible that these products will become a separate market."
Pioneering with high plant density
The first results show that good productions are recorded with the cultivation with a high plant density. The first selections therefore seem to be well chosen. "At least there was a lot of interest for it. We try to achieve the same productions as in the cultivation of heads. But even if we cannot match that completely, this cultivation method may be an improvement below the line, especially if you include the labor savings in the calculations. Cost price alone should not be the main goal, after all it is ultimately about a good and tasty product for the consumer."
Stefan speaks of pioneering. For that reason the open days are also very important. "This week everyone from the chain will visit us. They can ask us questions and share their experiences. Just like in greenhouse cultivation, we can continue to work on good varieties with the feedback from the processing industry, from the growers and from the retail sector. Both the end product and the cultivation technical aspect must ultimately be correct. You need everyone for that.”
Stefan with the lettuce planted at high density. "Sowing at high density is also possible, but this is more difficult because you will have a higher weed pressure and a lower uniformity. This makes it more difficult for the harvest and because the crop is two weeks longer on the field, the risks are also higher. However, this method of cultivation may be cheaper than planting it at high density.”
Intermediate step towards full convenience
A final development which Stefan likes to mention, is the demand from in particular the German market for an intermediate product between the whole head, still by far the majority in the German shops, and processed product, accounting for at least half of the fresh market in the Netherlands and Great Britain. "Here the convenience trend has already advanced much further. It is also developing now in Germany, but the consumers still want to have to do something with the product themselves, and therefore a bit of experience. That is why we are now looking for varieties in the baby leaf segment that need to be cut and washed, but that do not end up ready-to-use in the cold storage of the shop, but simply on the shelf. In order to be able to realize that, good shelf life is essential. The varieties Greenflash and Redflash are suitable for this."
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