Early assessment of herbicide efficacy after application with ALS inhibitors - a first exploration

摘要

Plants of Solanum nigrum (black nightshade) and Polygonum persicaria (redshank) were grown in a greenhouse until the fourth leaf stage. These plants were sprayed with a mixture of metsulfuron-methyl (100 and 75 g a.i./ha, respectively) and isodecyl alcohol ethoxylate (0.75 % v/v) using an air-pressured laboratory track sprayer. The level of carbon dioxide (CO_2) fixation as well as the relative quantum efficiency of photosystem II electron transport (PSn efficiency) and the relative quantum efficiency of photosystem I electron transport (PSI efficiency) were simultaneously assessed between 2 and 4 days after treatment. Measurements showed that CO_2 fixation, PSI and PSII efficiencies for treated plants were much lower than for unsprayed control plants. These results suggest that already few days after application the photosynthetic apparatus of S. nigrum and P. persicaria were affected by ALS inhibiting herbicides. An extensive set of experiments is being prepared to study these effects in more detail and to explore whether photosynthesis parameters can be used for early assessment of herbicide efficacy under field conditions.