Fruit & Vegetable Magazine

Features Production Vegetables
Producing seed potatoes in the open air


November 30, 1999
By Fruit & Vegetable

Topics

Soil is no longer necessary for growing potatoes, at least for growing seed potatoes.

Soil is no longer necessary for growing potatoes, at least for growing seed potatoes.

Newco, a potato technology transference company in Spain, is undertaking a research project, together with Neiker-Tecnalia from the Basque Institute for Agricultural Research and Development, for producing tubers in air by means of a novel system known as aeroponics.

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Never before in Spain has the first generation of seed potatoes been produced on a large scale by means of aeroponic growth. The system increases productivity, as more than 20 tubers per plant can be obtained instead of the three or four achieved using conventional methods. It also reduces the rate of soil-based diseases and is a more sustainable system, requiring lower inputs of water and fertilizers. Aeroponics makes it possible to provide precisely the correct amount of both items needed by the plant at each phase of its development.

The aeroponic system of cultivation for the production of first-generation seed potatoes is carried out in greenhouses and consists of maintaining the plant roots in the air and in conditions of total darkness. In order for the plant and the tubers to develop, nutrients are applied to the roots by means of a nebulizer system, where nutrient-enriched water is sprayed on them periodically. Roots grow in the air, and this enables a great exposure to air and avoids the contact of the tubers with soil pathogens.

One positive aspect of the system is that the progress of the tubers can be continually controlled, enabling their harvesting at the moment of optimum growth. In the case of first-generation seed potatoes, the most appropriate size is considered to be between 20 and 25 millimetres in diameter. In this way, a homogeneous production can be achieved – something that is not possible with traditional cultivation given that all the tubers are harvested at the same time and they do not show the same development or size.

The conventional production method for first-generation seed potatoes is based on high-density plantations in peat substrate and in greenhouses. This kind of production is highly labour intensive, with high costs due to the low numbers of tubers produced per plant (three or four tuber-seeds).

The production of seed potatoes follows a specific route map, starting with the in vitro multiplication of plants free of disease. These plants are then cultivated to obtain the tuber-seeds, or minitubers, which show a high health quality level and are the first-generation seeds (prebasic). These minitubers are the starting material for obtaining basic seed in its categories SuperElite and Elite. From this basic seed, Certificate A seed can be obtained, commonly employed to produce potatoes for consumption.

The Newco/Neiker-Tecnalia research project is aimed at developing the production of seed potatoes, something that is not being performed or achieved in Spain except in a very small quantity. The production of minitubers requires high technological skills and is currently practically non-existent in Spain. This means Spanish seed potato producers have to import them from countries like France, Holland and Scotland.