True potato seed (TPS)
In some countries TPS is used as a seed source while in other countries it is used on an experimental scale.
This seed is almost entirely disease free (most viruses are not transmitted by botanical seed).
There are various approaches:
The last two methods appear to have to have the best prospects.
- direct seeding
- seedlings raised in seedbeds and then transplanted
- seedlings grown in nurseries at high densities to produce seed tubers (seedling tubers)
Plantlets grown from TPS in a nursery can be transplanted 25-40 days after sowing, when plantlets have 4-5 leaves and are 8-12 cm high.
The planting distance of the plantlets is 25-30 cm between hills and 2-3 plants per hill.
Crops from botanical seed require a longer growing. Comparing a crop planted as transplants from TPS with one planted as seed tubers on the same date , will be 2-3 weeks later than the crop grown from tubers.
When damaged by adverse weather conditions during the early stages of growth, a crop grown from tubers will recover better than a crop grown from TPS.
Flowers, berries, tps------TPS-True Potato Seed------Development of potatoes from mini tubers
The method whereby seedlings are grown in nurseries at high densities (e.g. 100 seedling per m2) to produce seed tubers for crop production potentially offers prospects.
On 1 m2 surface 400-500 relatively small tubers (4 - 5 tubers/plant) may be produced.
TPS can either be from 'open pollinated' flowers of established varieties or be hybrids from parents selected for this purpose.
Since in TPS production sexual reproduction takes place, all the plants grown from TPS are of different genotypes (e.g. early or late maturing, different quality, different colour).
Under short day conditions the difference between maturity types will be less apparent than under long day conditions.
Effect of daylength and temperature on maturity
Concept: F1-Hybreds of diploid potatoes
Inbreeding of diploid potatoes is a new concept to produce TPS.
Self-compatibility is rare in potato diploid germplasm.
Inbreeding is crucial for F1-hybrid breeding.
Example:Pim Lindhout-Concept F1-hybrid breeding