Potatoes - quality aspects

Summary
The project has been conducted with minor changes. During the project we have already achieved a number of results that are considered valuable to the growers.

Test cooking has shown that a very fine quality can be achieved when using fresh or composted deep litter. The potatoes fertilised with slurry have a poorer taste. The taste, however, is not bad but somewhat diluted due to higher yields and lower dry matter content. The concentration of nitrate is higher and there is a tendency to darkening after cooking when using slurry.

Placement of slurry before seeding gave higher total yields and also higher yields in ware potato size.

The attacks of Rhizoctonia were weak in three of the four years of trial. No definitive conclusions can be drawn. However there was an expected tendency towards more severe attacks when using deep litter compared to slurry. The placement of manure (harrowing/ploughing) seemed to have an effect on the attacks, this hypothesis is investigated in a newer project.

Common scab on tubers is most profound when using slurry. When weeding was done by gradual ridging scab problems were reduced. This treatment also reduced the number of green tubers and improved yields of marketable sized potatoes compared to the normal treatment (harrowing-ridging). The yield improvement is believed to be caused by the slightly earlier emergence observed.

Variety trails included ten varieties. Differences in yield potential and resistance towards late blight have been observed. A number of quality measures was made to characterise the varieties. Some of the new varieties have so many valuable traits that a commercial use is predictable. However, the presently dominating variety, Sava is expected to hold a large market continually due to the excellent cooking quality.