Abstract
Using a developed chlorophyll (Chl) fluorescence imaging system, the photosynthetic effects of a commercially available soil-application type urea herbicide on attached Cucumis sativus L. leaves were analyzed.
Decreases in the stomatal conductance and the assimilation rate caused by the herbicide were detected with diffusion porometer measurements. However, a decrease in stomatal conductance was smaller than that in assimilation rate.
Photosynthetic injuries caused by the herbicide were detected with the Chl fluorescence imaging system. The inhibitions of primary electron transport in injured areas were detected from Chl fluorescence induction (CFI) images (Changes in intensity of Chl fluorescence during dark-light transition) taken by the CFI method. NPQ (non-photochemical quenching) and Yield (photosystem II photochemical efficiency) images were calculated from fluorescence images taken by the saturation pulse method. NPQ was reduced greatly in injured areas and NPQ images were useful to quantify the photosynthetic injuries. However, Yield was not reduced as much as the decrease in assimilation rate. This showed that Yield images were not suitable for diagnosis of the photosynthetic injuries of attached plant leaves caused by the herbicide.
