被动荧光探测水分胁迫对玉米叶片影响的初步研究

Preliminary study on the effects of water stress on maize leaf physiological status through passive chlorophyll fluorescence detection

利用叶绿素荧光被动探测方法初步探讨了水分胁迫对玉米叶片生理机能的影响。水分胁迫梯度通过将离体叶片放在干燥器时间不同而获得。室内采用积分球耦合A SD光谱仪,结合加/不加滤光片照明的方法得到反射率差值光谱,即代表叶绿素荧光光谱。结果表明随着叶片含水率的降低,叶绿素荧光发射峰的位置几乎没有变化,峰高在686 nm处有先上升后逐渐降低的趋势,在740 nm处则缓慢下降。双峰比值D if686/D if740与叶片含水率呈负相关关系(R2=0.3850,n=21),不同水分胁迫程度下利用调制式荧光仪测定的荧光参数F v/Fm与740 nm荧光光谱峰值线性正相关,与双峰比值有负相关趋势。表明该被动方法可以探测水分胁迫引起的叶片光系统受胁状况,为田间被动遥感探测植物叶绿素荧光和生理状态提供参考。

The authors studied the effects of water stress on leaf physiological status of maize （Zea mays L. ） detected by passive chlorophyll fluorescence（CF） measurements. By putting the detached maize leaves in a desiccator with different durations to obtain five kinds of water stress conditions. The leaf apparent spectra were measured under illuminations with and without a specially designed long wave pass edge filter, using a Li-Cor 1800 integrating sphere coupled with an ASD spectrometer. The CF spectra were derived from the reflectance difference spectra acquired under illuminations with and without the filter. The wavelength of fluorescence spectral peak shifted a little when leaf water content decreased. The CF peak values at 686 nm showed an increasing tendency followed by a decrease, while the CF peak values at 740 nm decreased gradually. The fluorescence intensity ratio of chlorophyll bands （Dif686/Dif740） was negatively correlated with leaf water content （R^2 = 0. 3850, n=21）. The CF parameters, Fv/Fm, measured by modulated chlorophyll fluorometer, were positively correlated with the degree of water stress severity while negatively correlated with Dif686/Dif740. The results indicated that the CF passively detecting technique could be employed to evaluate leaf photosystem status impaired by water stress, which provide a basis for probing the physiological status of crops.