Seed certification - quality of the seed planted - Netherlands
Pre-basic seed
The pre-basic seed comes either from rapid multiplication or from positive selection or clonal selection.
Clonal selection
Specialized producers of pre-basic and basic seed apply clonal selection. They may start annually with the tubers of 10-25 selected healthy looking plants of each variety they have in production. These tubers are either planted as progeny units (10-25) plants or in units of 200 plants.
Clonal selection
Automatic downgrading
In general a seed crop is certified as of a standard which is at least one class lower than the seed planted for its production ( S===>SE===>E===>A ,C ).
This automatic downgrading ensures that seed stocks are constantly renewed by either clean material from rapid multiplication or from clonal selection.
Seed classes-downgrading
With each generation the seed goes down one step, provided the seed meets the quality standard of that particular class.
The seed goes down by more steps if the seed does not meet the quality requirement of the first step that follows the class of the seed planted.
The highest class, which can be obtained from class SE is class E. From class E, the highest class that can be obtained is class A.