In order to investigate the effect of Serratia plymuthica A21-4 on cucumber growth and
rhizosphere soil microecology，A21-4 suspension was applied to rhizosphere soil of cucumber．The results showed
that the treatment of A21-4 could remarkably promote the cucumber growth and development both at seedling and
field stages，improve root system activity，increase cucumber yield and quality．Compared with the control，
treatment of A21-4 had increased cucumber yield by 32.22%，and the contents of protein，soluble sugar，and VC
were significantly increased．At the same time，A21-4 treatment could remarkably adjust cucumber rhizosphere
soil，and significantly increase activities of urease，phosphatase，sucrase and catalase in cucumber rhizosphere
soil．Besides，A21-4 treatment could increase the amount of bacteria and antinomycetes in cucumber rhizosphere
soil，and the available contents of N，P and K there．