Some Aspects of Glyphosate Action in Purple Nutsedge(Cyperus rotundus)

Research was conducted to determine effects of glyphosate [N-(phosphonomethyl)glycine] on the chlorophyll and carotenoid and on the catalase specific activity in purple nutsedge(Cyperus rotundusL.). The isopropylamine salt of glyphosate caused chlorosis to appear on the center leaves of plants maintained under lighted conditions after treatment. Glyphosate-induced chlorosis was delayed by darkness but occurred when treated plants were placed in the light. Glyphosate caused significant reducations in the chlorophyll and carotenoids content of purple nutsedge leaves. Based on levels in untreated plants, carotenoid content was reduced more rapidly than chlorophyll in glyphosate-treated plants. The catalase specific activity was reduced by glyphosate to about 70% of the level in untreated plants. Interrelationships among the effects of glyphosate on the carotenoid and chlorophyll content and catalase activity were not determined but possible interactions are discussed.