Xiaotian Gu1, Tianqi Huang1, Mengqiu Ding1, Weiping Lu1, Dalei Lu1. 1. Jiangsu Key Laboratory of Crop Genetics and Physiology/Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, PR China.
Abstract
BACKGROUND: Waxy maize (Zea mays L. sinensis Kulesh) suffers short-term exposure to high temperature during grain filling in southern China. The effects of such exposure are poorly understood. RESULTS: Starch granule size was increased by 5 days' short-term heat stress (35.0 °C) and the increase was higher when the stress was introduced early. Heat stress increased the iodine binding capacity of starches and no difference was observed among the three stages. Starch relative crystallinity was increased and swelling power was decreased only when heat stress was introduced early. Heat stress also increased the pasting viscosity, and this effect became more pronounced with later applications of stress. Heat stress reduced starch gelatinization enthalpy, and the reduction gradually increased with later exposures. Heat stress increased the gelatinization temperature and retrogradation enthalpy and percentage of the samples, with the increases being largest with earlier introduction of high temperature. CONCLUSION: Heat stress increased the pasting viscosities and retrogradation percentage of starch by causing change in granule size, amylopectin chain length distribution and crystallinity, and the effects observed were more severe with earlier introduction of heat stress after pollination.
BACKGROUND: Waxy maize (Zea mays L. sinensis Kulesh) suffers short-term exposure to high temperature during grain filling in southern China. The effects of such exposure are poorly understood. RESULTS:Starch granule size was increased by 5 days' short-term heat stress (35.0 °C) and the increase was higher when the stress was introduced early. Heat stress increased the iodine binding capacity of starches and no difference was observed among the three stages. Starch relative crystallinity was increased and swelling power was decreased only when heat stress was introduced early. Heat stress also increased the pasting viscosity, and this effect became more pronounced with later applications of stress. Heat stress reduced starch gelatinization enthalpy, and the reduction gradually increased with later exposures. Heat stress increased the gelatinization temperature and retrogradation enthalpy and percentage of the samples, with the increases being largest with earlier introduction of high temperature. CONCLUSION: Heat stress increased the pasting viscosities and retrogradation percentage of starch by causing change in granule size, amylopectin chain length distribution and crystallinity, and the effects observed were more severe with earlier introduction of heat stress after pollination.