Interaction of Prometryne and Phorate on Bean

The absorption by bean (Phaseolus vulgaris L. ‘Black Valentine’) of 2,4-bis-(isopropylamino)-6-(methylthio)-s-triazine (prometryne) at 1 μM concentration was increased in the presence of 10, 1, or 0.1 μM O,O-diethyl S-(ethylthio) methyl phosphorodithioate (phorate). An increase in absorption of 10 μM prometryne with addition of 1 μM phorate was recorded after 72 hr, but no increase was seen after 96 hr of absorption. Both prometryne and phorate inhibited state 3 respiration of mitochondria isolated from 6-day-old bean hypocotyls. Inhibition increased with increasing pesticide concentrations. When the pesticides were applied simultaneously, no interactions affecting state 3 respiration were observed. Neither prometryne nor phorate alone significantly affected phosphate accumulation by bean shoot mitochondria.