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Promoting Plant Growth By Rhizobacteria Under Salinealk-aline Conditions

Posted on:2021-05-16Degree:MasterType:Thesis
Country:ChinaCandidate:D D DuFull Text:PDF
GTID:2370330602496482Subject:Biological engineering
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Saline soil land is widely distributed in China,which is about one tenth of total salinization soil in the world.The soil salinization is very harmful to the agriculture,resulting in not only soil compaction and desertification,but also seed germination delaying,plant root system damage and the plant growth and development.Soil salinization is one of important factors to influence the grain yield and quality of crop in our country.In recent years,the application of biological methods such as microorganism or plant to recover saline-alkaline soil and increase the grain yield become a research hot spot.In this research,microorganisms were isolated from the Kalidium foliatum root grown in uncultivated shoals in Yinchuan,Ningxia Hui Autonomous Region.NaHCO3 and NaCl were used to mimic saline-alkaline stress and identified two microorganisms which could promote plant growth,named 1-9 and S2 5-12 respectively.By using 16 S rDNA sequences method,it was shown that 1-9 was Aeromonas veronii,S2 5-12 was Shewanella.Our studies found that Arabidopsis thaliana wild type Columbia growth was inhibited under high pH(pH?8)combined with NaHCO3 and NaCl,while 1-9 and S2 5-12 could reduce plant growth inhibition.At the same time,these two strains of microorganisms have excellent tolerance to salinealkaline stress.1-9 strain could still maintain high activity in the medium containing 11 mM Na2CO3,while S2 5-12 strain could still maintain high activity in the medium with 11 mM Na2CO3,11 mM NaHCO3 or 5% NaCl.Further studies found these two strains of microorganisms could not only promote root development of Arabidopsis thaliana under saline-alkaline stress,but also promote seed germination in different concentrations of NaHCO3 medium,which was probably caused by volatile acids generated from two microorganisms.Thus we speculated that microorganisns may adjust the abnormal high pH environment to promote the growth of plants.By detecting the ion content in Arabidopsis thaliana leaves,we found that 1-9 strain increased the content of phosphorus ion and potassium ion.Through soil pot experiment,we found that 1-9 and S2 5-12 could increase the maize growth under saline-alkaline conditions,such as root development,the fresh and dry weight of the plant.When 1-9 strain was used under saline-alkaline stress,the root total length and total surface area of maize were increased by 14.08% and 7.41% respectively.When S2 5-12 strain was used,the root total length and total surface area of maize were increased by 7.61% and 23.60%,respectively.Using 1-9 and S2 5-12 could increase maize yield in Binzhou City and Dezhou City test field by 7.03% and 7.92%,respectively.Microorganisms affected the nutrients content in the maize.In addition,microorganisms also influenced the growth of maize,which could manipulate plant height,leaf length and width.
Keywords/Search Tags:Saline-alkaline stress, PGPR, Crop, Volatile acid
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