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Arid Agriculture University Rawalpindi (2017)

ENHANCEMENT OF TREE SEED GERMINATION AND GROWTH BY USING PLANT GROWTH PROMOTING RHIZOBACTERIA (PGPR) ISOLATED FROM TREE RHIZOSPHERE

ANSARI, LUBNA

Titre : ENHANCEMENT OF TREE SEED GERMINATION AND GROWTH BY USING PLANT GROWTH PROMOTING RHIZOBACTERIA (PGPR) ISOLATED FROM TREE RHIZOSPHERE

Auteur : ANSARI, LUBNA

Université de soutenance : Arid Agriculture University Rawalpindi

Grade : Doctor of Philosophy (PhD) in Forestry & Range Management 2017

Résumé partiel
Microorganisms form an important part of the natural ecosystem by participating in the recycling of the chemicals and energy for life. The study area selected was Pothwar Plateau. Climatically research area is subtropical sub humid. Trees are one of the sources of fodder for livestock and are also used by local people for fuel wood and timber. Tree growth is stunted in these areas due to climatic factors and soil conditions because soils are poor in nutrients. Toaddress this problem, a series of research studies were carried out with the objectives to ; isolate and characterize rhizobial strains from tree rhizospheric soil and nodules using molecular and biochemical techniques, identification of most promising rhizobacteria by 16S-rRNA gene sequencing and confirming the effect of potential plant growth promoting rhizobacteria on growth of Acacia modesta, Acacia nilotica, Albizzia lebbek and Albizzia procera trees. Survey was conducted for the collection of forest rhizospheric soil and nodules from tree species of Acacia modesta, Acacia nilotica, Albizzia lebbek and Albizzia procera in Rawalpindi, Attock, Jhelum and Chakwal districts. The isolation of bacterial strains from root nodules was carried out after these bacteria were grown on yeast extract manitol (YEM) media and isolation of bacteria from rhizospheric soil was carried out through dilution plate techniques using Luria Bertani (LB) media. Strains were purified and preserved in glycerol stocks for further use. The purified strains were characterized for different PGP activities like phosphorus solubilization, hydrogen cyanide (HCN) production, gram staining, colony morphology, catalase test, oxidase test, N2 fixation through nif H gene amplification, siderophores and analysis for indole acetic acid. In addition to these activities proline contents of isolated bacterial strains addition to these activities proline contents of isolated bacterial strains were measured and the potential PGPR on the basis of PGP activities were identified using gold standard technique of 16s-rRNA gene sequencing. Data were analyzed statistically by least significant differences test (LSD) for comparisons of strains isolated. The study evaluated the important information regarding role of rhizobacteria for enhancement of tree germination and growth parameters of important tree species in Pothwar plateau. Seeds of four tree species were obtained from Range Research Institute (RRI), NARC Islamabad. Seeds were surface sterilized with 10% chlorox and then with 95% ethanol and thereafter washed several times with autoclaved distilled water. Colony forming unit (CFU) of inocula was kept 106 cells.

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Page publiée le 11 mai 2019