基于LMS算法的光合作用激发参数自适应技术

Self-adaptive method of excitation parameters in photosynthesis measurement based on LMS algorithm

主动式荧光诱导方法具有灵敏度高和不受外界光照因素等优点而被广泛应用到光合作用参数的测量,但因被测对象的吸收光谱特征存在差异性,需调整激发参数才能获得更准确的光合作用参数。为解决这一问题,依据植物光合作用电子传递过程,分析还原态初级电子受体比例激发光饱和条件,从而建立自适应参考模型,结合激发序列的递推关系和可变步长最小均方差算法对激发参数进行自适应调整,并通过对实验室培育的蛋白核小球藻进行实验对比分析。结果表明:经10次自适应过程后可将预设初始光强[8 600μmol quanta/(m2·s)]调整到最佳激发光强[34 270μmol quanta/(m2·s)],此条件下光化学量子产率(Fv/Fm)与WaterPAM结果相比误差最小;在常见藻类中,绿藻与蓝藻的最佳激发波长分别为460 nm、625 nm,而在520 nm激发时效率最低。该自适应调整算法为光合作用参数测量提供技术支撑。

With high sensitivity and less affected by the outside illumination, active fluorescence methods are widely used in photosynthetic parameters measurement. As the differences of the absorption spectra of plants, the excitation parameters by these methods are need to be adjusted in order to obtain more accurate parameters of photosynthesis. Based on the theory of photosynthesis electron transfer process, the saturation condition of the exciting light for the primary electron acceptor is analyzed, and corresponding adaptive reference model and variable step LMS algorithm are established according to the recurrence relation of the excitation sequence in this paper. The results show that only 10 rounds are needed for the Cinderella to adjust from the initial light intensity [ 8 600 μmol quanta/（ m2 s） ] to the appropriate light intensity [ 34 270 μmol quanta/（ m2 s） ]. The photochemical quantum yield （Fv/Fm ） under the appropriate light intensity has the smallest error compared with the results measured by Water-PAM. In common algae, the best excitation wavelengths for blue and green algae are 460nm and 625nm, the efficiency excited by 520nm is the lowest, respectively. The adaptive adjustment algorithm could provide technical support for photosynthetic parameters measurement.