Effect of Urea and Paclobutrazol to the Number of Soil Microorganism under Tribenuron Stress

A pot experiment was conducted to research the dynamic effect of urea and paclobutrazol on the number of soil microganism under tribenuron stress by plate counts for colonies at different sampling time.The results showed that urea and paclobutrazol significantly increased the number of soil bacteria,fungi and actinomycetes.Stimulative effect on soil bacteria was that: Tribenuron + urea Tribenuron + urea + Paclobutrazol Tribenuron + Paclobutrazol for the first 7 days;Tribenuron + urea + Paclobutrazol Tribenuron + urea Tribenuron + Paclobutrazol during14～60 days.Compared with the control,the average activation rate during 1 to 60 days was up to 552.7%.To soil actinomycetes,Tribenuron + urea + Paclobutrazol Tribenuron + urea Tribenuron + Paclobutrazol;Compared with the control,the average activation rate was up to 157.7%.To soil fungi,the effect of different concentration of tribenuron with urea and paclobutrazol was complex.Compared with the control,the average activation rate was up to 80.1%.Adding urea or paclobutrazol could alleviate or even eliminate toxicity effect of tribenuron on soil microorganism,and promote the recovery in soil microorganism contaminated by herbicides.