Study on Bamboo Associated Nitrogen Fixation

摘要

Acetylene reduction activities of several bamboo species root have been investigated andrndetermined. It is shown that with N2-backfilling method, the maximum activity of two kinds ofrnmonopodia bamboo (Phyllostachys heterocycla var. pubescens, Phyllostachys meyeri McClure) canrnreach to 3.9 and 2.1 nmol C2H4. g-1 dry root. h-1 respectively; with direct determining method, thernmaximum activities of four kinds of sympodia bamboo (Dendrocalamus latiflorus Munro,rnDendrocalamopsis beecheyana (Munro) Keng f., Bambusa textilis McClure and Bambusa chungiirnMcClure) can reach to 20.5, 24.8, 10.8, 7.5 nmol C2H4. g-1 dry root. h-1 respectively. When tested byrnenrichment culture method, for Ph. pubescens and Ph. meyeri, the maximum activities are 184 andrn160 nmol C2H4. g-1 fresh root. h-1; for D. latiflorus , D. beecheyana, B. textiles and B. chungii species,rnthe maximum activities are 978, 2743, 915, 397 nmol C2H4. g-1 fresh root. h-1 respectively. The numberrnof azotobacteria of four bamboo species at different rhizosphere position has been determined. It isrnshown that from non-rhizosphere soil to rhizosphere soil to root surface to root region the numbersrnof azotobacter increase sharply, and the rhizosphere effects of azotobacter are very obviously.rnIdentification has been done to azotobacteria isolated from Ph. pubescens and Ph. meyeri. It is shownrnthat in Ph. pubescens rhizosphere, the azoterbacteria mainly belong to Bacillus polymyxa andrnBacillus licheniformis. In Ph. meyeri rhizosphere, it is Klebsiella pneumoniae. Using these strains (2#,rn12#, 14#, 7#) to inoculating Ph. pubescens seedlings and D. latiflorus tissue culture plantlets, it isrnshown that inoculating associated nitrogen-fixing bacteria can promote plantlets growth.