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Dutch Prominent growers enthusiastic about Grodan's Elite-concept

This year, the Prominent innovation centre Groeneweg II, in 's-Gravenzande, the Netherlands, used Grodan's new "Single Plant System", Elite, in a 3.4 ha greenhouse.

"The results are amazingly positive," said Cornelis de Rijke, production manager at Prominent. Using Elite requires a different way of growing; it is a new concept. Cornelis says that "We adhere strictly to the concept's rules. Last year, we conducted a comparative test; we grew Roterno, a 100 gram tomato; 1.7 ha on our standard substrate Grotop Master and 1.7 ha following the Elite concept. We recorded a 5.3% increase in production in the same greenhouse and equal climatic conditions. The higher production took place mainly in the spring and autumn; we could also start harvesting 4 to 5 days earlier."

On the left, Cornelis de Rijke and on the right Gert-Jan Goes.

Clear difference 
This year, Prominent is cultivating the tomato variety Prunus following the Elite-concept. This breed is more generative than Roterno, a fruit with greater growing power, so the expectations are even higher. Cornelis de Rijke affirms that "we often ask ourselves how this is possible, but it works. We now see clear differences in the fruit's calibre. As horticultural grower, we want to move forward, and it looks like we have the right tool here."

Gert-Jan Goes of Grodan points out that a good drip system is important in order to get the best results from this concept. Gert-Jan says that "there is one plant block and one dripper per mat, and as a result the differences become clearer to see. With three blocks, those differences are normally more levelled, but they are less so with the Elite concept. Equality within the units is, however, optimised and no competition is to be found in the root zone. 

Additional control
Part of the Elite-concept consists in the use of a different irrigation strategy. In order to keep the sintering rate of 12%, an extra hour of dripping is added at the end of the day. Cornelis assures that "this extra hour does not result in greater vegetative growth, but in more vigour. Adjustments, especially in the stop time, directly lead to a generative or more vegetative reaction of the crop; we have clearly gained additional control."

The plant's hole in the Elite mat is not in the centre, and the dripper and drain opening also have a fixed position. This results in optimum irrigation efficiency; refreshing of the mat and thereby quicker and more efficient lowering of EC-content. Remarkably, the capillary action of the mat is improved; this is due to the higher density of the substrate in the upper section. The roots are therefore located particularly in the upper section and not so much at the bottom of the mat, where the oxygen/water balance is the most adequate. Cornelis: "For us, what matters of course is not to get a large root system, but the most efficient." 

Cornelis de Rijke points out that the price of this mat is higher, as well as the labour costs. Prominent takes this for granted. Cornelis laughs: "For us, what matters is the performance and that is good. This production increase is not comparable to other investments made in order to achieve a few percent increase in productivity." Prominent next year will expand the acreage with the Elite concept. Cornelis de Rijke of Prominent is already often approached by growers for more information on this subject. Also Gert-Jan Goes has noticed a growing interest in Elite.

For more information:
Gert-Jan Goes
Adviser substrate and irrigation
Email:[email protected]
Tel: +31 0651 51 82 49


Cornelis de Rijke
Head of production
Email: [email protected]
Tel: +31 0174 – 627 565