Woody Plants In The Rhizosphere Of Nitrogen Fixation - Camellia, Fir, Poplar, For Example

Tea-oil tree~. Chinese fir and poplar wcre tested to determine whether nitrogen fixation occurred in these woody plants. Three samples from tca-oil tree were labeled A1.. A2. M respectively;four samples from Chincsc fir were labeled B1.. B2.. B3 B4 respectively. The ecological distribution of microbe, enzyme activities and values of pH in rhizosphere soil of tea-oil tree were analvscsed and compared with bulk soil ,so were Chinese fir Results of analysis and comparison indicated that the factors above-mentioned had no positive correlation with the ecological distribution of N2-fixing bacteria in rhizosphere soil of tea-oil tree and Chinese fir. But the reasons and the correlation weren抰 known. Root-associated,N2-fixing bacteria were isolated ,with modified D鯾ereiner medium,from rhizospere,non-surface-steriliied and surface-sterilized root of the three woody plants aforesaid. Bacteria were confirmed as N2-fixing ones ,using the acetylene reduction assay(ARA). Enzyme activity of eight strains isolated from tea-oil tree was more than lnmolC2H.~ per milliliter per hour with a maximum activity of 2.76nmoIC2H4.h?ml?Six strains from Chinese fir with a maximum activity of 2.49nmolC2H4.h?mV? Twelve strains from poplar with a maximum activity of 2.98 and 2.76nmolC2H4.W?mr? Studies were initiated to determine the effect of different medium~. hydrocarbon.. temperature and pH value on nitrogenase activity of four strains which were Aa33.. Ba4 1.. y12 and Y22. Results showed that: the first.four strains had different nitrogenase activity cultivated on different media with a maxium activity on modified Doberciner medium; the second ,different strain showed different activity on different hydrocarbon media, but all of them showed the highest activity on sucrose media. next on sodium apple acid mediu; the third, the temperature range for nitrogen activity was approximately 200C?00C,as for Aa33 and yl 2,the temperature of maximal nitrogcnase activity was 350C,and for Ba41 and Y22, was 300C?50C ;the fourth ,of four strains,the opttimal pH value of nitrogenase activity from yl2 was approximately 6.O,which from the others was 6.O?.O,And of all strains the limitation of pH values for nitrogenase activity?was about 5.0?.0. All of the four strains were tested for cultural features,further,two of them were tested for physiological and biochemical features. According to standard biochemical and cultural features ,Strain yl2 was classified as Flavobacterium. Strain Y22 was identified as A Icaligenes.