Effect of Interaction of Waterlogging and High Temperature after Anthesis on Photosynthetic Characteristics of Flag Leaf and Yield in Winter Wheat

Abstract

Waterlogging and high temperature are main stress factors during late growing period of winter wheat(Triticum aestivum L.) in Yangtze Valley region of China.To understand the effect of interaction of waterlogging and high temperature on photosynthetic characteristics and grain yield of wheat,we carried out a pot experiment,using the variety of Yannong 19,in continuous growing seasons from 2009 to 2011.At grain-forming(5-8 d after anthesis) and milking(15-18 d after anthesis) stages,waterlogging(1 cm of surface water layer),high temperature(35±2℃ of daytime/25±2℃ of nighttime),and waterlogging + high temperature stresses were imposed to wheat plants,separately.Waterlogging,high temperature,and both stresses showed significantly effects on photosynthetic characteristics of flag leaf and yield reducing photosynthetic rate(Pn),chlorophyll content(SPAD reading),stomatal conductance(Gs),and transpiration rate(Tr);enhancing intercellular CO2 concentration(Ci);and declining grain number per spike,1000-grain weight,and grain yield.However,in the case,spike number per pot was not affected significantly.Thus,the effects of waterlogging and high temperature on Pn did not result from stomata factor of flag leaf.The average relative injury rates(RIR) of yield were 37.7% for waterlogging + high temperature treatment,21.1% for waterlogging treatment,and 17.6% for high temperature treatment.Stress showed higher RIR at grain forming stage(30.8%) than at milking stage(20.1%).There was significant interaction between waterlogging and high temperature,and grain-forming stage was more sensitive to the interaction than milking stage.