Abstract: In order to study the impact of sewage irrigation and cadmium stresses on the growth process and cadmium accumulation in spinach(Spinacia oleracea L.),the spinach planted in pots were irrigated and sprayed with tap water and sewage water,both containing Cd2 +of various concentrations. The results show that Cd2 +-containing sewage imposed higher inhibiting effects than the Cd2 +-containing tap water,as evidenced by lower values of plant height,leaf area and average number of leaves per pot,as well as the significantly higher cadmium concentrations in the tissue. The comparisons with the control group show that the tissue cadmium increased along with the increasing of Cd2 +exposure concentration in both treatments of Cd2 +-containing tap water and Cd2 +-containing sewage water. Two distinguishable stages of the increase in tissue cadmium were identified. At the first stage,significant linear relationships with correlation coefficients of 0. 999 6 and 0. 997 6 were observed with the slopes of 1. 602 9 and 1. 665 6 for the spinach exposed to 0- 10 mg / L of Cd2 +-containing tap water and Cd2 +-containing sewage water respectively. At the second stage,significant linear relationships with correlation coefficients of 0. 997 9 and 0. 999 8 were observed with the slopes of 0. 237 3 and 0. 254 8 for the plants exposed to 10- 50 mg / L of Cd2 +-containing tap water and Cd2 +-containing sewage water respectively. The slope of the second stage is notably smaller than the first stage. The threshold concentration of cadmium pollution to spinach growth was found 10 mg / L. The Cd2 +-containing sewage water may stimulate spinach growth at low concentration,but impose inhibition at higher concentrations,in the measurement of spinach height,leaf area,number of leaves,stem diameter and biomass.

Key words: Sewage irrigation, Cadmium stress, Spinach, Accumulation, Growth

CLC Number: 

• S636.1