Pre-basic and basic seed production methods

Methods used to produce pre-basis and basic seed are: Seed plot technique
The seed plot technique is a seed production method used at farm level, mainly for the farmers' own seed supply. It is used for varieties of which no seed is produced in commercial seed programmes. There are several variations in the method, as an example: Healthy looking plants are tagged (marked) during the growing season. At harvest the tubers from tagged plants are bulked and used for a seed production field next season. In this new seed production field the same procedure is repeated during the following seasons. The system is applied to improve the seed quality of highly appreciated, often old cultivars with special culinary qualities and agronomic characteristics, of which no disease free seed can be obtained from seed programmes.
Seedplot technique

Clonal selection
For clonal selection tubers of healthy looking plants are selected and planted next season as progeny units. The progenies are multiplied and kept as separate units for at least two generations. If in the first year in a certain progeny unit (or clone) one infected plant is found, all plants of the progeny are destroyed. This to avoid the risk of the disease spreading and to assure that the basic seed produced in this manner is clean.
Clonal selection
The identification of diseased plants is based on visual observations, supported by serological tests(mainly for virus and bacterial diseases).
In the example given, four healthy looking plants are selected. In generation 1, one clone was rejected. In generation 4 one plot (0.3 ha) did not meet the standard for pre-basic and was sold as commercial seed. The result is that from the four selected plants in 4 generations 16 tonnes of pre-basic seed is produced. To accommodate the programme for these 4 generations approximately 1 ha of land is required.
CLONAL SELECTION - NETHERLANDS

In-vitro multiplication
In this system, nodal cuttings from selected healthy plants (or from plantlets derived from meristem tip culture) are grown on an agar medium. When plantlets have developed 6-9 nodes (and leaves), again nodal cuttings are made and planted on agar medium. This process may be repeated several times. This way a large number of plantlets can be produced in a relatively small laboratory under well controlled conditions. The plantlets obtained in this way are rooted and planted in a soil substrate (often in a protected environment: screen house) for the production of tubers.
IN-VITRO MULTIPLICATION

Viability
Pre-basic and basic seed programmes require regions and conditions where: The production costs of pre-basic and basic seed are high and financially viable only when seed stocks can be kept clean for at least 4 field multiplications.

Botanical seed
In certain conditions T.P.S. may be used as a source for clean seed.
TRUE POTATO SEED (T.P.S.)