Trifluralin effects on carrot callus tissue

The effect of trifluralin on the growth, oxygen uptake, and adenosine phosphates level of carrot (Daucus carota L.) callus tissue was determined over a period of 18 days after subculture. The herbicide (10^?4 and 10^?5M) reduced fresh weight gain significantly; the reduction was less with lower trifluralin concentrations. Dry weight accumulation was not inhibited until after Day 6 of the test period and thereafter was reduced by all concentrations tested. Oxygen consumption was inhibited by trifluralin (10^?4 and 10^?5M) throughout the test period. Concentrations of 10^?6.10^?7, and 10^?8M produced variable effects. The response profile of O₂ consumption in the presence of dinitrophenol was different from that of trifluralin. Analysis of adenosine phosphates level gave no clear response trend. Energy charge values of 0.7 to 0.85 were obtained for untreated tissue. Trifluralin had no effect on energy charge until Day 9 (10^?4M) and after Day 15 (all concentrations).