叶绿素荧光成像技术监测苗期小麦白粉病初探

A preliminary study on the monitoring of wheat powdery mildew at seedling stage based on chlorophyll fluorescence imaging technology

为探究叶绿素荧光成像技术在小麦白粉病监测应用中的可行性,本研究对接种6个不同浓度小麦白粉菌分生孢子的小麦幼苗离体叶段、一叶一心期幼苗和二叶一心期幼苗以及接种后不同时期进行叶绿素荧光成像测定,并对导出的叶绿素荧光参数与病情严重度的关系进行分析。结果发现,接种不同浓度白粉菌分生孢子的小麦离体叶段或幼苗的Fv/Fm图像可以在一定程度上反映出小麦白粉病菌的侵染程度。接种小麦白粉菌后第3天,Fv/Fm值随接种浓度的变化规律不明显,但从接种后第5天开始,Fv/Fm值随接种浓度的增加而下降,且未接种的小麦幼苗或离体叶段的Fv/Fm值显著高于接种处理,接种浓度最高(5 mg/mL)的处理其Fv/Fm值显著低于同时期其他接菌处理。小麦白粉病严重度与叶绿素荧光参数之间的相关性分析表明,Fv/Fm和Chlidx与病害严重度均极显著负相关,在此基础上,分别建立了小麦离体叶段、一叶一心幼苗及二叶一心幼苗的基于参数Fv/Fm或Chlidx的病害严重度估计模型。对模型的拟合效果进行比较发现,基于Fv/Fm或Chlidx的病害估计模型其RMSE或R^(2)比较接近,因此叶绿素荧光参数Fv/Fm或Chlidx用来估计苗期小麦白粉病发生程度是可行的。本研究为叶绿素荧光成像技术在小麦白粉病监测预警中的应用奠定了理论基础,具有一定的应用前景。

To investigate the feasibility of applying chlorophyll fluorescence imaging technology for monitoring wheat powdery mildew,chlorophyll fluorescence measurements were performed on detached leaf segments of wheat seedlings,one-leaf wheat seedlings and two-leaf wheat seedlings inoculated with six different concentrations of Blumeria graminis f.sp.tritici(Bgt) spores,and the relationships between the chlorophyll fluorescence parameters and disease severity were analyzed.The results demonstrated that Fv/Fm-images of wheat leaf segments or seedlings inoculated with different concentrations of Bgt spores could reflect the infection degree of Bgt to a certain extent.The Fv/Fm values showed no obvious change with inoculum concentrations on the 3 rd-day after inoculation,but from the 5 th-day,the Fv/Fm values showed a downward trend with increasing inoculum concentrations.The Fv/Fm values of wheat seedlings or detached leaf segments in the non-inoculated control treatment were significantly higher than those in the inoculated treatments,and the Fv/Fm values in the treatment group with the highest inoculum concentration(5 mg/mL) were significantly lower than those of other treatments in the same period.Further analysis of the correlations between the disease severity and chlorophyll fluorescence parameters showed that Fv/Fm or Chlidx were significantly negatively correlated with disease severity.On this basis,disease severity estimation models based on Fv/Fm or Chlidx were established.Comparing the fitted models,it was found that the values of RMSE or R^(2) of the disease estimation models were relatively close based on Fv/Fm or Chlidx for detached wheat leaf segments,one-leaf wheat seedlings and two-leaf wheat seedlings,respectively.Therefore,it is feasible for chlorophyll fluorescence parameters(i.e.,Fv/Fm or Chlidx) to be used for estimating the severity of wheat powdery mildew at seedling stage.This study laid a theoretical foundation and had a prospect for application of chlorophyll fluorescence imaging technology to the monitoring and early warning of wheat powdery mildew.