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

Abstract

acetamide] on photosynthesis and respiration of isolated 10-day-old hypocotyl-epicotylcells from three Phaseolus taxa was investigated. Herbicide concentrations of 1 x 10-12 , 1 X 10-1°, 1 X 10-8 ,1 X 10-6 ,1 X 10-4 and 5X 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. asetamied] se effek op fotosintese en respirasie van 10-da9-oue hipokotiel-epikotiel selle van drie Phaseolus taksa is ondersoek. Onkruiddoderkonsentrasies van 1 x 10-2, 1 X 10-1°, 1 X 10-8 , 1 X 10-6 , 1 X 10-4 en 5 x 1 0-3 M is gebruik. Beide prosesse is deurgaans deur die onkruiddoders gestimuleer. Fotosintese by Kamberg droebone is die meeste (328%) deur metolachlor gestimuleer, terwyl die proses by Nierbone met 25% deur dieselfde onkruiddoder ge'I'nhibeer is. Die grootste effek op respirasie was by Kamberg boontjies waar die proses met 12% geinhibeer is deur metolachlor, terwyl respirasie Nierbone met 39% deur dieselfde onkruiddoder gestimuleer is. Die algemene tendens was stimulering van fotosintese en respirasie, maar met respirasie wat minder gestimuleer is as fotosintese. Resultate dui daarop dat hierdie asetaniliede verskillende reaksies in verskillende Phaseolus taksa veroorsaak tydens die blootstelling aan spesifieke onkruiddoderkonsentrasies vir spesifieke tye.