Chlorophyll Fluorescence and Yield Responses of Winter Wheat to Waterlogging at Different Growth Stages

The agronomic and physiological effects of waterlogging in winter wheat were examined at four growth stages in the 2011 / 2012 and 2012 / 2013 seasons. In both seasons, the greatest yield penalties occurred by waterlogging at the filleting stage (10%-15% decrease), followed by the jointing stage; however, waterlogging at the grain filling stage had less effect on the yield. The lower grain yield caused by waterlogging at the tillering stage was primarily reflected in reductions in spike and grain numbers per m(2). Waterlogging at the jointing and booting stages reduced grain weight through reduced dry matter translocation. In addition, waterlogging at the filleting stage significantly reduced chlorophyll content and thus photosynthetic capacity, resulting in a lower F-v / F-m ratio, apparent electron transport rate (ETR), effective quantum yield of photosystem II (Phi PSII) and photochemical quenching (qP). However, waterlogging at the grain filling stage improved the leaf photosynthetic capacity and grain yield. We found that the filleting stage was most the susceptible to waterlogging in wheat; therefore, the maintenance of photosynthetic performance after anthesis could be a reasonable strategy for increasing grain yield.