Location: Vegetable Crops ResearchTitle: Heat stress during development alters post-harvest sugar contents and chip processing quality of potato tubers
Submitted to: American Journal of Potato Research
Publication Type: Proceedings
Publication Acceptance Date: 3/10/2015
Publication Date: 7/19/2015
Citation: Wiberly-Bradford, A.E., Busse, J.S., Bethke, P.C. 2015. Heat stress during development alters post-harvest sugar contents and chip processing quality of potato tubers. American Journal of Potato Research. Paper No. G40.
Technical Abstract: Environmental stresses that increase tuber contents of the reducing sugars glucose and fructose decrease the value of chipping potatoes because such tubers produce dark-colored chips that are unacceptable to processors and consumers. Stem-end chip defect (SECD), which causes regions of dark color along the vasculature of potato chips at a position corresponding to the tuber basal end, is an economically important tuber quality defect that occurs erratically across locations and years. Controlled-environment studies conducted over 3 years tested the hypothesis that exposure of potato plants to short periods of high temperature stress causes SECD. Multiple cultivars were grown under control conditions with 25°C day and 18°C night temperatures. A high temperature stress, with 35°C day and 29°C night temperatures, was imposed for 3 to 14 days. Plants were returned to control conditions until vines senesced naturally, typically 45-60 days later, when tubers were harvested. Little SECD was observed in chips prepared at harvest from control or heat-stressed tubers. SECD was abundant in chips from heat-stressed, but not control, tubers after 30 or more days in storage at 13°C. Heat stress increased tuber glucose and fructose contents, and invertase activity increased as SECD severity increased. Different genotypes varied widely in susceptibility to heat stress-induced SECD. In a separate experiment, lines of potato in which vacuolar invertase activity was suppressed using RNA-interference had reduced SECD severity in field-grown tubers, suggesting that invertase activity produced highly localized accumulations of glucose and fructose that are the precursors of SECD.