So that we can always offer our customers the best young plants, we have opted for our own in-house quality assurance. Our quality assurance is fundamentally a multi-level system that covers all stages of micropropagation: starting with the first plant material, which we get from a (new) variety, then to the starting material up to the actual micropropagation and also beyond that to the finished young plant, which bears fruit again.
This article is intended to refer exclusively to the internal quality of the plant material. We will write a separate article about the quality assurance of the actual young plant.
A new variety comes to our company
As mentioned at the beginning, we start our quality assurance before the actual micropropagation. With the first material, which we obtain from a variety or selection, we attach great importance to already tested material that is virus-free. This material is usually provided by the breeders. If no tested material is available, we also rely on untested material and then perform the appropriate tests ourselves. As soon as we get plant material of new varieties/selections, this material is planted out or potted in our variety testing garden.
Our variety testing garden
Picture: Variety testing garden at our location in Strullendorf
In our variety testing garden there are all of the varieties that are being propagated, the new breeding selections that are in the test/trial phase, but also varieties that are now no longer being propagated. We then have all these plants produce fruits, so that we can look at and judge the fruits. This is because our requirement is that we want to see a fruit at least once before the beginning of the micropropagation in order to determine the value of a variety or selection. The fruits are looked at from a pomological point of view and described to check whether a variety has really bred true. At the same time, the inner quality of the fruits is also checked, whether it may have deformed fruits or, more importantly in the case of the raspberries, if they have crumbly fruits. If undesirable plants are discovered, they will be destroyed immediately. Of course, the flavour of the fruits of a variety is evaluated because that matters with our varieties; the taste has to be convincing. Also, in the variety testing garden, even before the plants start to flower, the first testing for viral diseases is carried out because some viruses are transmissible via pollen.
If everything is fine with this pomological inspection, the micropropagation will begin at the beginning of the next growing season. In addition to the fruits and the state of health, of course, the growth character of a variety or selection is examined and the general plant health is also evaluated. This is because it does not help if the best-tasting variety is marketed, but the plants have little chance of survival in the home garden.
The starting material and the actual beginning of micropropagation
The material for the start of micropropagation is obtained in different ways depending on the genus. Either it is obtained directly from the examined plants from the variety testing garden or from plants that are situated in a weather protected location during the vegetation period, so that there are fewer infections when they come into the laboratory. A very common method is also the formation of so-called 'sister plants', in which these plants are obtained either by cuttings, root cuttings or rooted runners. Depending on the genus, material for the micropropagation of the respective sister plants is usually obtained two years in a row before they are renewed. This ensures that always the pomologically checked material is propagated.
Again, immediately before the micropropagation, a virus test for relevant viruses is again performed. This is done so that we can ensure that only healthy plant material is used for propagation.
In addition, the dual control principle applies when harvesting the sister plants. This ensures that the later young plants can be traced back through all propagation steps to a single plant in the variety testing garden.
Picture: plants during micro-propagation in a climate-room
Another important element of our quality assurance takes place directly in the laboratory during micropropagation. Thus, the plant material used for micropropagation is renewed in regular cycles. Each material is only used in the laboratory for a certain amount of time or for a certain number of propagation steps before it is renewed. In this way we prevent the alteration of the propagation material by too many propagation steps. We also work extremely cautiously with plant hormones to prevent mutations and other changes in the plant.
The finished young plant
Picture: sellable young plant after successful propagation
Even after successful establishment of the micropropagated young plants and after commercial propagation, there is still a final stage of quality assurance. Young plants are taken from the inventory on a random basis. These are potted and then allowed to bear fruit in the variety testing garden. Thus, even after successful propagation, we still have the opportunity to check the young plants for varietal identity and pomological quality. Ultimately, we want to know for sure that what we put into the propagation system at the beginning also comes out.
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