The effect of acetanilide herbicides on photosynthesis and respiration in isolated hypocotyl-epicotyl cells from three Phaseolus taxa

Abstract

The effect of alachlor [2-chloro-N-(2,6 diethylphenyl)-N-methoxymethyl) acetamide], metolachlor [2-chloro-N- (2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] and acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl) acetamide] on photosynthesis and respiration of isolated 10-day-old hypocotyl-epicotyl cells from three Phaseolus taxa was investigated. Herbicide concentrations of 1×10⁻¹², 1×10⁻¹⁰, 1×10⁻⁸, 1×10⁻⁶,1×10⁻⁴ and 5×10⁻³ M were used. In most instances, both processes were stimulated by these herbicides. The highest stimulation of photosynthesis was found with metolachlor on Kamberg dry beans (328%), while inhibition of the same process by 25% occurred with Kidney beans. Respiration of Kidney beans was stimulated by a maximum of 39% using metolachlor but inhibited by 12% in the case of Kamberg beans. The tendency was for these herbicides to stimulate photosynthesis and respiration. Respiration, however, was not as strongly stimulated as photosynthesis. Results suggest that these acetanilides exhibit different responses in different Phaseolus taxa exposed to specific herbicide concentrations for specific periods.