大气CO2浓度倍增和施氮对冬小麦光合及叶绿素荧光特性的影响

摘要

The experiment was conducted to investigate the effect of doubled atmospheric CO2 concentration, nitrogen application on the photosynthetic rate and chlorophyll content and fluorescence parameters of two winter wheat cultivars with pot-culturing method in Open Top Chamber (OTCs). The result showed that under elevated atmospheric CO2 concentration, the photosynthetic acclimation appeared in wheat leaves of no nitrogen application but the photosynthetic acclimation did not appear in wheat leaves of nitrogen application. Compared with the background CO2 concentration (375 μmol · mol-1) ,doubled CO2 (750 μmol · mol-1 ) significantly reduced the leaf chlorophyll content, Fm, Fv, Fv /Fm and Fv/F0 values, and increased F0 value of two wheat cultivars at the four stages of jointing,booting,anthesis and middle grain-filling. Nitrogen application could evidently increase the leaf chlorophyll content, Fm, Fv, and Fv/F0 values, and decreased F0 values of two wheat cultivars at the four stages. The effects of doubled CO2 concentration on the leaf chlorophyll content and fluorescence parameters of wheat cultivars were significant at the 0.05 level under no nitrogen application, whereas were indistinct under nitrogen. Therefore, the doubling of atmospheric CO2 concentration would inhabit leaf photosynthetic rate,chlorophyll content,the photosynthetic electron transport and the potential activity of PS Ⅱ of winter wheat,while nitrogen application could eliminate its effects.%采用开顶式气室,通过土培盆栽实验研究了不同大气CO2浓度(背景空气浓度375 μmol·mol-1和倍增浓度750 μmol·mol-1)和氮素水平(不施氮和施氮0.25 g/kg)下两个冬小麦品种('小偃6号'和'小偃22')主要生育期(拔节、孕穗、扬花、灌浆期)叶片叶绿素含量和荧光动力学参数的变化.结果显示,与背景CO2浓度相比,在不施氮条件下大气CO2浓度倍增处理的小麦叶片出现明显的光合下调现象,而施氮时变化不明显;同时,CO2浓度倍增后小麦各主要生育期叶片叶绿素含量均有不同程度地下降,荧光参数初始荧光(F0)值明显提高,最大荧光(Fm)、可变荧光(Fv)、最大光能转换效率(Fv/Fm)和PSⅡ潜在活性(Fv/F0)值均显著降低.施氮可提高冬小麦各个时期叶片叶绿素含量、Fm、Fv、和Fv/F0值,降低F0值;不施氮条件下,大气CO2浓度倍增对冬小麦各主要生育时期叶绿素含量和荧光参数的影响明显,而施氮后影响微弱.研究表明,大气CO2浓度升高对冬小麦光合速率、叶绿素含量和光系统Ⅱ(PSⅡ)的光合电子传递和潜在活性具有一定抑制作用,通过施氮可以有效地缓解其负面效应.