Many minitubers minimises the chance of mistakes CULTIVATION AND TECHNOLOGY as easily killed when you add fungicides to the water, which means that we don’t add fungicides any longer after a few trials. And so, the cultivation process is nearly organic. Fungicides…, we don’t see them much really. That’s because we keep the air as dry as possible 24/7 now, which means that the stems and leaves of the plant won’t get any moisture on them. From our fungicide trials in the greenhouse, we have also learnt how to use them in the field. When the chemicals we use for Rhizoctonia come too close to the hair roots, for example, they can also harm the root formation. So we’re extra careful in that respect now.’ ‘The thing is that because of the faster multiplication and its subsequent multiplications, the chances are that you make fewer mistakes.’ there is first the changing room for putting on special shoes and an overcoat. This is to prevent pests and diseases entering the cultivation space. In the passage from the changing room to the greenhouse, there is closable netting, again to prevent possible insects such as aphids entering the space. The greenhouse is divided into five sections, as De Schutter shows us. Every section has its own potato variety in containers through which water with nutrients flows. Roots and tubers are covered with light-resistant plastic. Each section has a harvest of 25,000 minitubers, which means that the five sections together produce 125,000 tubers. There are two harvests a year, which brings the total annual harvest to 250,000 minitubers. The first harvest takes place during the months of March to July and the second from July to November. There is always one full-time worker attending, if necessary supplemented by a temporary worker and father and son De Schutter. Knowledge and skills Although the hydroponic system is not difficult to set up, the cultivation itself requires considerable knowledge and skills. Each variety gets its own special nutrients compound. In addition, the nutrients in the vegetative growing stage differ from those in the generative growing stage. ‘We more or less play around with the nutrients; it’s a matter of knowledge and experience.’ After three years, the partners have learnt their lessons, Junior tells us enthusiastically. ‘Humidity in the greenhouse is quite difficult to control, but it is very important for the live plants. Especially when they are still very small. In order to get to grips with that, we first keep those small plants in a separate space, a sort of incubator. In the micro-climate that we maintain here, the young plants are able to harden off before they are moved to the greenhouse proper. We have also discovered that it’s difficult to protect the roots and tubers from the light. If the slightest bit of light reaches the roots, the plant will not make any tubers, only leaves. It took us at least two years before we had found suitable felt root cloth and plastic. Fungicides disastrous What we’ve also learnt is that you need to be extremely careful with applying fungicides. Fungicides kill the fine mycelium. A plant’s hair roots are almost as fine as mycelium and they are Client satisfaction The most important thing with growing minitubers is that it leaves you with satisfied customers. The biggest customer is Averis to which the partnership delivers 40 percent of their third-generation S seed. ‘Averis breeds starch varieties and, in that sector, the replacement and/or renewal of varieties is much faster than in the consumption sector. That’s why a fast system of variety development suits them very well. Moreover, Averis is very particular where quality is concerned, because our seed goes to areas with a much higher disease pressure. In order to grow another field generation there, it is important that the start is clean and that can be achieved with this type of minituber cultivation. I’d like to repeat that fast multiplication needn’t necessarily be better than less-fast methods, but if you know exactly what you’re doing, the chances are that you make fewer mistakes, we reckon. I’m quite convinced that the customers agree.’ Besides basic seed for Averis, the partnership also grows S seed for trading companies and various seed potato growers. A considerable part of that also consists of the multiplication and marketing of free varieties, a percentage of which is grown for export. As this is our own trading activity, the partnership has also recently become a member of the Dutch Potato Organisation (NAO). ● Leo Hanse A plant’s hair roots are almost as fine as mycelium and they are as easily killed when you add fungicides to the water. Potato World 2011 • number 3 13 Pagina 12
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