The effects of the date of defoliation of the seed potato crop and the storage temperature of the seed on subsequent growth: 1. Sprout growth

Abstract

Seven experiments carried out over 3 years investigated the effects of the date of defoliation of the seed crop and the storage temperature of the seed on subsequent sprout growth.The time of defoliation of the seed crop had a small, variable effect on the number of sprouts but with all varieties in every year, early defoliation gave the greatest total sprout length. The effect of later defoliation on sprout length varied according to the variety and the year. Most of the variation in total sprout length per tuber appeared to be attributable to differences in the date of dormancy break of the seed tuber.Storage throughout the winter at 15 °C gave fewer sprouts but a greater total sprout length per tuber than storage at 9 °C. A linear relationship between total sprout length per tuber and accumulated day degrees above 0 °C from dormancy break accounted for most of the variation in sprout length occurring in Désirée, Pentland Crown and Majestic as a result of storage at 9 °C and 15 °C for different periods of time.