Tuber Water and Pressure Potentials Decrease and Sucrose Contents Increase in Response to Moderate Drought and Heat Stress

Environmental stress during the growing season can reduce the quality of stored Solanum tuberosum (potato) tubers. Changes in greenhouse grown Russet Burbank tuber water potential and tuber composition following periods of moderate drought, heat, or drought and heat stress were characterized. Decreased leaf and tuber water potentials were observed at the end of stress treatments. Decreased tuber water potential caused dramatic declines in tuber pressure potential. Tuber sucrose content increased with the severity of stress. Changes in tuber glucose and malic acid contents were also observed. Stress during early tuber bulking had a larger effect on tuber sugars at the end of the stress period than stress during late bulking. Stem-end glucose concentration of tubers at harvest after vine senescence was greater in tubers from plants stressed at early tuber bulking compared to late bulking.