UPTAKE OF THE HERBICIDE DIURON AS VISUALIZED BY THE FLUORESCENCE IMAGING TECHNIQUE

A new fluorescence imaging system for monitoring the uptake of the PSI I-herbicide diuron (DCMU) was tested in tobacco leaves. UV-laser-induc ed (lambda(exc) = 355 nm) fluorescence images were collected for blue fluorescence F440 (lambda(em) = 440 nm), green fluorescence F520 (lamb da(em) = 520 nm), red chlorophyll fluorescence F690 (lambda(em) = 690 nm) and for far-red chlorophyll fluorescence F740 (lambda(em) = 740 nm ). Diuron-treated leaf parts exhibited a higher red and far-red chloro phyll Fluorescence emission (F690 and F740) than untreated leaf halves , whereas the blue and green fluorescence, F440 and F520, remained una ffected. As a consequence, the fluorescence ratios blue/red (F440/F690 ) and blue/far-red (F440/F740) significantly decreased in diuron-treat ed leaf parts. The time course of diuron uptake into the leaf could be followed by fluorescence images taken 10 and 30 min after diuron appl ication. The novel high resolution fluorescence imaging method supplie s information on the herbicide uptake of each point of the leaf area. Its great advantage as compared to the point data fluorescence measure ments applied so far is discussed.