Abstract
Experiments were conducted to elucidate the effects of the inoculation of a mixture of several free-living rhizobacteria; Azotobacter, Bacillus, Enterobacter and Xanthobacter which were collected and screened for the nitrogen-fixing ability in China, on nitrogen accumulation, growth and grain yield of rice plants. The inoculation of several bacterial species significantly increased acetylene-reducing activity in the roots of rice plants. The total dry matter yield, grain yield and nitrogen accumulation were increased by the bacterial inoculation by 6 to 13%, 15 to 18%, and 10 to 24%, respectively, in the experiments of 1997 and 1998. The increase of grain yield was associated with the increase of root length and leaf area, and also with the increase of chlorophyll content and photosynthetic rate during the grain-filling period. It was hypothesized that the inoculation of free-living rhizobacteria to rice plants led to increase of nitrogen accumulation in the plants, stimulation of the leaf photosynthesis particularly in the grain-filling stage resulting in the increased dry matter and grain yield.
