A method of testing the resistance of potato cultivars to tuber damage caused by squeezing

Abstract

SUMMARYTubers from nine cultivars grown in four plantings over 3 years at two sites in Scotland were tested for resistance to cracking by squeezing between two flat surfaces. The force was applied by a lever to which a steel plate was fixed, pressing the tuber against a wooden base. The weight on the lever was recorded when wet hair-line cracks appeared on the tuber surface.There were significant differences between cultivars from the same planting. The rank positions of some cultivars were relatively stable but others differed widely between plantings. The grouping of cultivars into the upper, middle or lower parts of the range for squeezing resistance was similar to that for resistance to external damage based on Potato Marketing Board farm surveys. The test could be used to help breeders identify genotypes highly susceptible to external mechanical damage. If combined with tests of resistance to other types of mechanical abuse common in the bulk handling of tubers a more accurate estimate of damage resistance on the farm should be possible.