Effects Of Environmental Heterogeneity On Nodule Characteristics Of Podocarpus

Podocarpus belongs to the ancient gymnosperms,and it is the actual production of the use of fine tree species,However,with the development of human civilization,the natural environment is affected to varying degrees,and the environmental factors will deal with Podocarpus and nitrogen fixation microorganisms This symbiosis system has a certain impact.In this study,we studied the nodule characteristics of Podocarpus in different areas of Guangxi,and provided scientific basis for exploring the evolution of nodules and nitrogen-fixing bacteria.It also plays an important role in enriching the theory of biological nitrogen fixation and promoting the research and utilization of biological nitrogen fixation.The results are as follows:(1)The morphological characteristics of the soil factor had a certain effect on the nodule size and nitrogenase activity of Podocarpus,it were not changed in different habitats,but the climate and environmental factors had different effects on the nodule size and nitrogenase activity of Podocarpus.On the one hand,there was a negative correlation between nodule diameter and latitude and longitude,which was positively correlated with annual mean temperature and accumulated product temperature,and the correlation with the relative humidity was the largest,which was less correlated with the mean temperature in July.On the other hand,There was a significant positive correlation between the activity of nitrogen fixation and latitude,monthly mean temperature and average annual rainfall,and had no significant positive correlation with longitude,annual mean temperature and activity accumulated temperature,and the negative correlation with annual rainfall was the largest,And the monthly mean temperature is less relevant.And the results showed that the contents of nutrient elements(except phosphorus)could also promote the nitrogenase activity of Podocarpus,and the nitrogenase activity of Podocarpus could be inhibited to some extent with the acidification of soil.(2)The soil factor had a certain effect on the nodule size and nitrogenase activity of Podocarpus.On the one hand,the lighter the soil texture,the greater the diameter of nodules,the higher the activity of nitrogenase.On the other hand,the nodule diameter was positively correlated with the total nitrogen content of the soil and promoted the growth and development of the nodules.It was negatively correlated with the potassium content and negatively correlated with the contents of nitrogen,phosphorus and available potassium,The growth and development of nodules play a certain inhibitory effect,while the organic matter content and the relative diameter of mature tumors is relatively low.There was a negative correlation between soil nitrogen and nitrogen content and soil organic matter content,and there was a significant positive correlation with nitrogen content,(3)Through the isolation and culture of endophytic nitrogen-fixing bacteria of Podocarpus dahuricus in different ecological areas of Guangxi,it was concluded that the same species of rhubarb root cannabis could separate different endophytic Rhizobium and Frankia actinomycetes,while the same area can also be separated from the different morphological characteristics of endogenous nitrogen-fixing Rhizobium and Frankia actinomycetes,indicating that there were diversity of endophytic nitrogen fixation in Podocarpus sinensis.(4)The results showed that the isolated nitrogen-fixing bacteria could stimulate the nodulation of sterile Podocarpus seedlings,and the nodule was basically consistent with the root of Podocarpus.In the three methods,the nodulation rate was Rhizobium>Frankia>Rhizobium + Frankia,and the nodule diameter was Rhizobium>Rhizobium + Frankia>Frankia.Rhizobium The ability of nodulation of the seedlings is stronger than that of Frankia,and when the two strains are present at the same time,the nodulation of Podocarpus can be counteracted.It is also known that the number of microbial species in different habitats is also related to the growth and development of nodules have a certain impact.