Stem-End Defect in Chipping Potatoes (Solanum tuberosum L.) as Influenced by Mild Environmental Stresses

Abstract

Global consumption of potato (Solanum tuberosum L.) continues to shift from fresh potatoes to value-added processed food products such as potato chips. One serious tuber quality defect of chipping potatoes is stem-end chip defect, which results in chips with dark-colored vasculature and adjacent tissues at the tuber stem end after frying. In this study, treatments of moderate water deficit for 14 days, alone or in combination with moderate daytime heat stress at 30 °C, as well as varied chemical maturity of tubers at harvest were imposed in controlled-environment greenhouses. Only temperature stress for 14 days in 1 of 2 years significantly changed the occurrence of stem-end chip defects. Water deficit for 14 days and chemical maturity of tubers harvested at four time points from early tuber bulking to after vine senescence did not have significant impacts on defect incidence or severity. Biochemical analyses showed that more severe defects with larger areas of dark color on the stem end of chips were associated with increased amounts of tuber stem-end glucose and increased stem-end acid invertase activity. We conclude that moderate environmental stresses and maturity of tubers at harvest are not sufficient to consistently cause stem-end chip defect.