Effects of domestic sewage effluents on the growth and physiological characteristics of Catharanthus roseus

Potted plants of Catharanthus roseus were selected for irrigation treatments with municipal domestic sewage effluents.The treatments were triplicately divided into four treatments according to effluents：tapwater（V／V）：Ⅰ，1:0；Ⅱ，1:1；Ⅲ，1:2；control，0:1.The results showed that compared with the control，sewage irrigation treatments increased the contents of soil NH₄⁺-N from 59.01mg／kg to 64.22～65.89mg／kg，NO₃^--N from 2.69mg／kg to 3.03～4.54mg／kg，available P from 32.29mg／kg to 37.40～42.41mg／kg.Meanwhile，sewage irrigation also enhanced the activities of soil enzymes such as catalase，urease and protease，with increases of 10.76%～23.32%，33.41%～103.69% and 31.82%～131.82%，respectively；promoted root activities from 170.25μg／g·h to 177.88～471.69μg／g·h，increased chlorophyll contents from 1.78mg／dm² to 2.68～2.98mg／dm²，and biomass from 11.660g／pot to 12.130～16.577g／pot.Of all of the treatments，treatment of effluents：tapwater（V／V）1:1 had the best effects on plant growth.Although irrigation with undiluted effluents didn’t benefit for plants’utilization of nutrients from the irrigating effluents，it didn’t exert significantly negative effects on the growth and biomass accumulation of C.roseus.