ATRAZINE INHIBITION OF ION UPTAKE BY PLANT-ROOTS

Excised roots of maize, barley, and wheat showed inhibition of the sulfate uptake capacity in the presence of 10-4 M atrazine. In maize roots the inhibition was only slightly affected by the length of atrazine incubation and promptly relieved when atrazine was removed from the nutrient solution. On the contrary, in barley and wheat roots the inhibition of sulfate uptake capacity increased with increasing incubation time and persisted after atrazine removal. The uptake pattern at different atrazine and sulfate concentrations was characteristic of a linear noncompetitive inhibition in maize, and of a partial competitive inhibition in wheat and barley. [14C]Leucine uptake was slowed by atrazine in barley, but its incorporation into protein was unaffected in barley, wheat, and maize roots. Two maize genotypes showed differences in the susceptivity of the sulfate uptake mechanism to atrazine. © 1979.