Screening Of Plant Growth Promoting Bacteria And Studies On The Mechanism Of The Action

Rehmannia glutinosa Libosch is a perennial herb of Scrophulariaceae, and is one the earliest medicinal plants that have been cultivated in China. Its root is used frequently as a crude drug in traditional Chinese medicine. Continuous cropping obstacle is very serious in the current production, but its reason is not clear up to now. In order to reveal the reason of continuous cropping obstacle, Liufeng isolates 50 bacteria from the soil, where Rehmannia glutinosa Libosch has never been cultivated. Studies primarily on their biologic characteristic, finally discovers that their abilities of using stachyose and producing cyanide contents have significant difference. All these prompt especial nutriture in rhizosphere, Rehmannia glutinosa Libosch has ever been cultivated, may results in disequilibrium of microecosystem, then results in continuous cropping obstacle.In this dissertation, first, in order to determine plant growth promoting rhizobacteria and deleterious rhizosphere bacteria, we test the effect of single rhizobacteria upon growth of rehmannia glutinosa plantlets and rehmannia glutinosa in potted plant trial, and integrated with former work; then, do rhizobacteria antagonism trial, in order to investigate their antagonistic relationship; finally, it's investigated that the extract of rehmannia dride rhizome has antotoxicity to Rehmannia glutinosa plantlets, furthermore the selected plant growth promoting rhizobacteria have ability of significantly lessening antotoxicity of extract of rehmannia dride rhizome. The main findings are as follows:1. Different bacterias had significant effect upon growth of Rehmannia glutinosa plantlets. Bacterias were divided into four types according to the effects, i.e. Plant growth promoting rhizobacteria (PR), it includes 6,23,24,28,29; plant causing ineffective rhizobacteria (CIR) it includes 4,7,12,13,34,41; plant growth inhibiting rhizobacteria (IR), it includes 3,15,18,35; and plant causing death rhizobacteria (DR) it includes 11,26,37,48.2. In potted plant trial, different bacterias had significant effect upon growth of Rehmannia glutinosa plantlets. part of soil rhizobacteria, such as 6,7, 24,28,29,34promoted growth of rehmannia glutinosa, furthermore, 24,28,29,34 had significant difference compared with control group.3. In rhizobacteria antagonism trial, it's investigated that part of plant growth promoting rhizobacteria antagonistic ability.4. It's investigated that extract of rehmannia dride rhizome has antotoxicity to Rehmannia glutinosa plantlets.5. It's investigated that part of plant growth promoting rhizobacteria have ability of significantly lessening antotoxicity of extract of rehmannia dride rhizome.In conclusion, soil bacteria had significant effect upon growth of Rehmannia glutinosa; extract of rehmannia dride rhizome has antotoxicity to Rehmannia glutinosa plantlets; furthermore, the selected plant growth promoting rhizobacteria have ability of significantly lessening antotoxicity of extract of rehmannia dride rhizome.Innovation in this dissertation:1. It's the first time to reveal the effect of single rhizobacteria upon growth of rehmannia glutinosa plantlets and rehmannia glutinosa in potted plant trial.2. It's investigated for the first time, that the extract of rehmannia dride rhizome has antotoxicity to Rehmannia glutinosa plantlets.3. It's investigated for the first time, that part of plant growth promoting rhizobacteria have ability of significantly lessening antotoxicity of extract of rehmannia dride rhizome.