Ecophysiological Effect Of Inoculation With Endophytic Diazotrophic Bacteria Strains To Tamarix Ramosissima Ledeb. Under Salt-drought Stress

Endophytic diazotrophic bacteria are the microorganisms that colonizing and various living plants tissues and establishing symbiosis relationship with the host, these bacteria are believed having features such as nitrogen-fixing, at the same time, it has a wide range of biological and ecological role such as IAA-producing activity, solubilizing phosphate and iron activity, enhancing plant disease and heavy metal resistance, improving drought and salt environmental stress, and has important application value in promoting host nutrient absorption and competitiveness, enhancing the host of biotic and abiotic stress resistance and improving the ability of adapting to environment. Study effect of inoculation endophytic diazotrophic bacteria strains isolated from the root of T. ramosissima and L. ruthenicum at the lower reaches of Tarim river on physiological and ecological characteristics under salt-drought stress, discussing the colonizion dynamic, body conduction performance and nitrogen-fixing efficiency in desert plants. The main results showed:The DENB20 strain can improve the seed germination rate of T. ramosissima. The height, fresh and dry weights, root shoot ratio, chlorophyll content, root activity in endophytic-inoculated plants were higher than those of endophytic-free plants under salt-drought stress. At the same time, the strain can significantly improve the plant biological nitrogen-fixing, increase the plants total P, promote growth in plants and increase stress resistance of plant.The protective enzymes activity (SOD, POD, CAT) in endophytic-inoculated plants were higher than those of endophytic-free plants. In addition, inculcation with DENB20 strain can also help improve the non-enzymatic defensive system, such improving the plants RWC, decreasing WSD,MDA and Pro content, cell membrane permeability etc., all of these showed that the strain can enhance the stress resistance of T. ramosissima seeding.The strain can improve the total quantities of rhizosphere soil microorganisms under non-stress and stress conditions, the ratio of bacteria to fungi and actinomycetes to fungi were higher than endophytic-free plants which express increased with soil salinity increases, besides, it can also significantly improve the rhizosphere soil organic materials, rapidly available N, P, K, total soluble-salt contents under stress conditions, thus changed the rhizosphere micro chemical and physical environment, promoted rhizospheric soil moisture and nutrition conditions, promoted the growth in plant.The strain DENB55 with the mutagen treatment, obtain the strain DENB55k+s which could resist the concentration of 80μg·mL-1 Kanamycin Sulfate and 80μg·mL-1 Streptomycin. The strain can only colonization in L. ruthenicum, While DENB20r+s strain can colonization in L. ruthenicum and P. hendersonii. When inoculationing DENB20r+s in L. ruthenicum and P. Hendersonii, the nitrogen-fixing efficiency in P. hendersonii were higher than that in L. ruthenicum, When inoculationing DENB20r+s and DENB55k+s in L. ruthenicum, the nitrogen-fixing efficiency of DENB55k+s were higher than DENB20r+s.