Laser-induced time-resolved fluorescence of vegetation

Time-resolved measurements of the laser-induced chlorophyll fluorescence emission of vegetation detected by two different techniques are described. Fluorescence decay time measurements using single photon counting and picosecond laser pulse excitation have been used to analyze the fluorescence heterogeneity of plant leaves. The fluorescence is described by lifetimes of 10-40, 80-150, 400-500, and 700-1000 ps. By closing the reaction centers via application of the herbicide DCMU, the lifetimes of the two slowest components increase by a factor of about three. Another possible method to monitor the fluorescence after picosecond excitation could be a streak camera detection system. Measurements performed on the slow decay component of stressed and unstressed plants are presented. >