Atrazine Uptake by Sudangrass, Sorghum, and Corn

The uptake of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) was studied in sudangrass [Sorghum sudanense(Piper) Stapf, var. Piper], grain sorghum [Sorghum bicolor(L.) Moench], and corn (Zea maysL.) to find whether differences in atrazine uptake exist among these species. The uptake of atrazine followed closely the growth patterns of corn, sorghum, and sudangrass during the first 5 weeks of growth. Concentration of14C from ring-labeled14C-atrazine in the soil reached a peak in corn, sorghum, and sudangrass plants after 2 weeks of growth and then declined. The14C concentrations were two to three times greater in sorghum and sudangrass than in corn throughout the 5-week period. Atrazine uptake per gram of plant growth by these crops was directly proportional to the concentration of atrazine in the soil and the proportionality factors were in the order: sudangrass < sorghum ≫ corn. Total uptake and the total growth were in order: corn ≫ sorghum = sudangrass. In a study where relative humidity was a variable, the amount of atrazine absorbed per ml of water was inversely related to total water usage.