Starch Granule Size Distribution and Pasting Characteristic Response to Post-Anthesis Combined Stress of Waterlogging and Shading

The combined stress of waterlogging and shading (WS) caused by continuous rain threatens the production of high-quality weak gluten wheat in China (Triticum aestivumL.). To evaluate its influences on wheat quality formation, Yangmai 158 was chosen to be subjected to WS at 0-7 days after anthesis (DAA, WS0-7), 8-15 DAA (WS8-15), 16-23 DAA (WS16-23), and 24-31 DAA (WS24-31), respectively, with non-stressed plants as control (Non-WS). Compared with Non-WS, WS reduced the amylopectin content and enhanced amylose content in the mature grains. WS enhanced the number and surface but reduced the size of the starch granules. The number, volume, and surface area percentages of B-type starch granules were enhanced, and the number and volume percentages of A-type starch granules were reduced by WS. The peak viscosity and gelatinization temperature were enhanced and the low viscosity and final viscosity were decreased by WS. WS applied at the mid-grain-filling stage (WS(8-15)and WS16-23) had greater modification on the starch content, granule size distribution and pasting characteristics than that applied at early (WS0-7) or late (WS24-31). The changes of starch pasting characteristics under WS had a significant correlation with the amylase and amylopectin content, amylase/amylopectin, and the ratio of the volume percent of B-type and A-type starch granules.