| Abrus cantoniensis Hance, named Jigucao in China, is a leguminous medicinal plant used for curing acute and chronic hepatitis, liver cirrhosis presently. Except for its medicinal value, it is also a kinds of Chinese traditional medicine for export and gradually accepted. But in its culture, farmers liked to fertilize the nitrogen fertilizers excessively for the highly yield, thus inducing emergence of diseases and insect pests. As a result, pesticide residues had increased, the content of effective components was decreased and environmental pollution had appeared. In this study, we carried firstly out the research of biological characteristics of its rhizobia, and then studied the influences of rhizobia and some other factors on growth, nodulation, nitrogen-fixation efficiency and its effective components content in pot culture. Meanwhile, the accumulative dynamic fluctuation of effective components of the herb cultured in different localities had been researched. The research results might help to solve the above problems by biological nitrogen-fixation and give the scientific principle for the harvesting of Abrus cantoniensis Hance. The main results are as follows:1.The rhizobium of Abrus cantoniensis Hance had the average generation time of 14.8 h, and might be slow-growing rhizobium. The rhizobia of Abrus contoniensis Hance had significantly differences in biological characteristics. These differences showed as follows: one was that the rhizobia had the higher tolerance to high temperature, and could live in the temperature from 20℃ to 35 ℃ while stand shortly in the extremely high temperature of 60 ℃ for 10 min, but couldn't survive below 15 ℃ and above 40 ℃. The second was that the adaptability to acidic environment had diversity. According to the reaction to pH values of medium, the strains could be divided into three types, that were acid-tolerant, neutral and broad-ranged strains, respectively. The acid-tolerant strain could grow well in pH4-5. Lastly, the strains differed greatly in the sensitivity to antibiotics. The sensitivity of different strains to the same antibiotic or the same strain to different antibiotic differed greatly. Every strains had the highertolerance to Neo but had the weaker tolerance to Amp and Spc. The results showed that the rhizobia of Abrus cantoniensis Hance could evolve different special ecological types that they could adapt to the different environment.2. the growth and nodulation capacity of seedlings of its seeds collected from different localities didn't have difference significantly. This result might predict that the different seeds from different localities might have the same genetic backgrounds of controlling growth and nodulation of the seedlings. Strains from different environment had different influences on the growth and nodulation. There were significant differences among strains. The nodulation rate, dry weight of nodule and biomass of the seedling inoculated the strain from Yulin significantly increased, and this strain showed the higher ability of nodulation and nitrogen-fixation.3. The influence of different nitrogenous compounds on the growth, nodulation ability of the seedlings of Abrus cantoniensis Hance were different. The three compounds, (NH4)2SO4, NH4NO3, and KNO3, could enhance the vegetative growth variously. Among these compounds, the higher concentration of 5 mmol. L-1 of ammonium sulfate had best effects on vegetative growth of seedlings, and KNO3 was worst. The influences of different kinds of nitrogenous compounds differed significantly on seedling height, aboveground biomass and total biomass. Meanwhile, it was found that the nodulation and nitrogen-fixation of seedlings was obviously inhibited by nitrogenous compounds. Their inhibitory influences ranked NH4N03> (NH4)2S04>KNO3. The higher concentration treatments (5 mmol.L-1) of NH4N03 and (NH4)2SO4 inhibited the nodulation of seedlings or even couldn' t nodulate, and the treatment of 5 mmol.L-1 of NH4NO3 completely inhibited the nodulation , named such thing as zero-nodulatin pheno...
|
PDF Full Text Request