Assessment of the physiological vigour of new potato cultivars in Switzerland

Summary

Dormancy, incubation periods and physiological vigour or rusticity of new potato cultivars were determined during the official cultivar assessment programme in Switzerland. A total of 60 cultivars were assessed, including the standards, Sirtema (early), Bintje (mid-early) and Eba (mid-late); Russet Burbank was re-examined. Large variation between cultivars was observed, from 2000 to 3400 day-degrees for dormancy and from 1900 to 3700 day-degrees for incubation periods, expressed as sums of cumulated temperatures above zero centigrade. Field trials with physiologically aged seed identified the physiological vigour or rusticity of the cultivars. Those with low vigour or low rusticity showed poor emergence and yield after prolonged sprouting periods. The lowest produced less than 10% of the yield of seed of optimum physiological age stored under standard conditions. However, some high vigour or very rustic cultivars produced 100% of their potential yield. There was no relationship between earliness and physiological vigour. Vigour is very useful to farmers because it indicates those cultivars that are sensitive to warm storage or long sprouting periods and desprouting before planting.