Effects of salt stress on microbial biomass and enzyme activities in rhizospheric soil of sugarcane

This study measured the microbial population size，enzyme activity and their relationship in rhizospheric soil of sugarcane at four different salt stress levels with four sugarcane varieties as materials. The results showed that， under the salt stress levels of 0.0%，0.2%，0.5%，0.8%，the sugarcane rhizospheric soil bacteria，actinomycetes，fungi number and urease，sucrase，catalase enzyme activity reduced significantly with the increase of salt stress，especially the differences between salt stress and no salt stress were extremely significant. These indicated that the sugarcane rhizospheric soil microbial population was sensitive to salt stress，their growth inhibited，a sharp reduction was found in the number，and the soil enzyme activities had the same performances. Correlation，partial correlation and canonical correlation analysis showed that under saline stress，there was a significant linear correlation and canonical correlation between sugarcane rhizospheric soil microbial biomass and enzyme activity. There was a significant partial correlation between actinomycetes number and invertase，catalase activity，as well as urease activity and invertase activity.