Effect of Methanol on Photosynthesis and Chlorophyll Fluorescence of Flag Leaves of Winter Wheat

作     者：ZHENG Yue-jin YANG Yue-qin LIANG Shan-shan YI Xian-feng 

作者机构：College of Agriculture Henan University of Science and Technology Luoyang 471003 P.R.China 

出 版 物：《Agricultural Sciences in China》 (中国农业科学（英文版）)

年 卷 期：2008年第7卷第4期

页      面：432-437页

学科分类：09[农学] 0901[农学-作物学] 

基　　金：Henan University of Science and Technology,HUST: 2007142 Henan Province University Innovation Talents Support Program: 2008 HASTIT003 

主　　题：methanol photosynthetic activity chlorophyll fluorescence flag leaf winter wheat 

摘      要：Photosynthesis and chlorophyll a fluorescence parameters, photochemical efficiency of PS II （Fv/Fm）, photochemical quenching of PS II （qP）, nonphotochemical quenching of PS II （NPQ）, maximum activity of PS II （Fv/Fo） as well as electron transport rate （ETR）, and quantum yield of PS II （ФPS II） were measured on flag leaves of the winter wheat treated by methanol at different concentrations. The results revealed that photosynthesis was greatly improved by methanol, as indicated by higher photosynthetic rates and stomatal conductance. The enhancement effect of methanol on photosynthesis was maintained for 3-4 days. Different methanol concentration treatments also increased intercellular CO2 concentration and transpiration rates. No significant decline was found in Fv/Fm, Fv/Fo, and ФPS II, which revealed no photoinhibition during methanol application in different methanol concentrations. Methanol showing no apparent inhibitory effects indicated higher potential photosynthetic capacity of flag leaves of winter wheat. However, the increase in photosynthesis was not followed by an increase in the photosynthetic activity （Fv/Fm）, and fluorescence parameters did not indicate an improvement in intercellular CO2 concentration and PS II photochemical efficiency compared with the control, thereby encouraging us to propose that lower leaf temperatures caused by applied methanol would reduce both dark respiration and photorespiration （most importantly）, thus, increasing net CO2 uptake and photosynthetic rates.