Influence of R-40244 on pigment content of wheat and corn

Chlorophyll production by wheat (Triticum aestivum L. ‘Mericopa’) and corn (Zea mays L. Merit) was severely curtailed by the experimental herbicide l-(m-trifluoromethylphenyl)-3-chloro-4-chloromethyl-2-pyrrolidone (R-40244). A 96% loss in chlorophyll content was observed in wheat seedlings treated with 320 μmol/1 R-40244. In corn 320 μmol/1 R-40244 caused a 40% drop in chlorophyll content. Carotenoid production in both wheat and corn was inhibited by R-40244, 320 μmol/1 of the herbicide causing a 97% reduction in wheat and a 44% reduction in corn. The inhibition of carotenoid production which, in turn, allows chlorophyll to be photooxidized, may represent the mode of action of R-40244. Hill reaction activity was not detected for R-40244.