The eff ects of natural factors (temperatures +34°C and +20°C) and anthropogenic xenobiotics (1,2,4-TriH; 1-(CH3 SO2 )-1H-1,2,4-Tri; 4-(PhSO2 )-4H-1,2,4-Tri; 4-(TolSO2 )-4H-1,2,4-Tri) on watercress Lepidium sativum L. was studied. For this, 4 series of experiments were carried out. In the fi rst two series, the eff ect of concentrations was studied: 0.001, 0.01, 0.1 mg/ml during germination at diff erent temperatures for three days.