Isolation and Evaluation of Nitrogen Fixing Bacteria in Tea Soils for the Production of Biofertilizer
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Date
2013
Journal Title
Journal ISSN
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
The field practices are very important and soil is very significant factor that consider in the
agricultural crop production and management. Though each and every field practices are
important, the soil fertility management is most significant one. Synthetic and organic fertilizers
generally used to provide nutrient elements. Nitrogen is an essential nutrient component that has
several beneficial effects on the crop growth. And also, nitrogen is a limiting nutrient which can
be identify in the soil in cultivable lands for growth and yield of crops. Several kinds of
microorganisms engage with Biological Nitrogen Fixation, Azospirillum bacteria is an
associative micro aerophilic nitrogen fixer commonly found in association with the rhizosphere
and roots of a variety of plants including cereals and grasses. They have the ability to produce
usable form of nitrogen for the plants when they functioning in the soil biosphere. The present
study was aimed to isolate Azospirillum spp.from tea soils, root parts of rehabilitation grasses in
tea plantations and maize and study their nitrogen fixing abilities aiming at applying the
Azospirillum as Biofertilizer in Tea lands.
Methodology
This research was carried out at the Microbiology laboratory of Uva Wellassa University, Soil
samples and parts of root samples of Mana (Cymbopogan confertiflorus), Guatamala
(Tripsacum laxum), Guinea (Panicum maximum) grasses and Maize (Zea mays) were collected
from the university premises, farmer fields and tea estates closer to Uva Wellassa University,
Badulla. Sample collection was done from well grown, healthy plants. All samples were
collected in polythene bags to prevent the contamination and water evaporation. Collected soil
samples were sieved. 10g of even sized soil samples were mixed with 100ml of distilled water
and kept on an orbital shaker for 30 minutes. 1ml of aliquot was taken from the above sample
and ten-fold soil dilution series was followed up to10 The 0.1ml of aliquot taken from the 10 soil dilute was inoculated into semi solid medium and also washed solution of roots, leaf parts
and distilled wash root parts were inoculated in to test tubes containing Nitrogen free
Bromothymole blue (NfB) semisolid media. All the tubes were inoculated at ambient
temperature 30 C to 32 C for 48 hrs and the growth was observed by formation of subsurface
white pellicles. The pellicles of each sample were streaked on NfB solid media and incubated at
ambient temperature (28 C). Purified Azospirillum isolates were named as 100 series and stock
cultures were prepared for further studies.
Isolated Azospirillum spp were examined for identification of their Gram reaction, shape and
motility. 0.2 ml of isolated bacterial broth were inoculated into 20 ml of NfB semisolid medium
and allowed to incubate at 32 C for 10 days. The efficiency of Nitrogen fixation was determined
after10 days using micro kjeldahl analysis.
Description
Keywords
Agriculture, Export Agriculture, Tea Industrials, Tea Technology, Soil Science, Biofertilizer