Growth-promoting effect by inoculating 3 strains of associative nitrogen-fixing bacteria in sugarcane.

【Objective】 The present study was conducted to investigate the growth-promoting effect of sugarcane plantlets by inoculating with three associative nitrogen-fixing bacteria strains.【Method】 Eight treatments,viz.,control,3 single strain treatments(strains 11-31,07-98 and 08-200) and their 4 combination treatments were designed to investigate the effects of their inoculums on sugarcane cultivar ROC22 using pot test.The growth and physiologicalbiochemical characteristics of plants were assessed in 86 days after inoculation.【Result】 Statistic analysis revealed that all of the 7 inoculate treatments resulted in significant increase in biomass,plant height,total nitrogen and phosphorus contents and root activity of sugarcane plants.The best promoting effect was showed by the treatment Ⅳ,compared with none inoculated control,its'biomass,plant height,and phosphorus content increased by 60.79%,25.23% and 76.29%,and total nitrogen also increased 45.79%.【Conclusion】 This study indicated that the 3 associative nitrogen-fixing bacteria strains can be used as potential inoculants of sugarcane,and different inoculated methods show significant differences on growth-promoting effect,which depends on species of nitrogen-fixing bacteria and combination methods.It will be significant for further studies on the applications of nitrogen-fixing bacteria as biofertilizer.