Study on Flag Leaf Light Curve and Chlorophyll Fluorescence Parameter of Winter Wheat in Grain Filling Stage

Zhao Wei; Li Zhen; Wang Qian; Chen Jingling; Chen Manli

doi:10.16765/j.cnki.1673-7148.2017.01.009

Abstract：In order to understand the characteristics of photosynthesis of winter wheat photosynthetic organs in grain filling stage,this research utilizes the chlorophyll fluorescence which is a sensitive pointer of photosynthesis.Winter wheat(Xinong979)was planted in the experimental base of Henan Agricultural University to study the diurnal variation characteristics of photosynthesis and the effect of high temperature stress of flag leaf in filling stage using Mini-PAM chlorophyll fluorescence system.The index ofthe lightresponse curvewas measured to explore the light saturation pointand the half-saturated light intensity.The results showed as follows.1) Light saturation point in grain filling stage of winter wheat was 2236.5 μmol/ (m2 · s),and the half-saturated light intensity is 647.7 μmol/(m2 · s).It was showed that the flag leaf of winter wheat have strong tolerance of bright light in grain filling stage.2) The high temperature stress phenomenon appeared in the process of measurement.The response of Fv/Fm,qP,qL and Y(NO) which indicated photosynthesis to high temperature stress fluctuation was relativelybig.Y(Ⅱ) reached the maxi mum of all day at 10am,then decreased continuously with increasing temperature.The result of rETR,qN,NPQ,Y(NPQ) and the response of Y(Ⅱ) to high temperature stresswereall mutual authentication.They were sensitive to environmental changes and can be used as sensitive index indicating the strength of the plant photosynthesis.3)The turning points of qN,NPQ,Y(NPQ) and Y(NO) became stable at 36 ℃ in their changing course with treatment temperature increasing.It indicated that 36 ℃ was the index temperature at which photosynthetic organs of winter wheat became inactivation,or to be destroyed.The damage was stablewhen when the temperature was above 41 ℃,and it would be very serious.