STUDIES ON MICROBIAL DIVERSITY AND THEIR ACTIVITY IN SOIL UNDER BAMBOO PLANTATION
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Date
1998-08-19
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK ,BANGALORE
Abstract
Investigations were carriedout on the rhizosphere microflora of bamboo
as well as their population and activities under leaf litter of bamboo
plantation during different seasons. The enumeration of microflora in the
rhizosphere of different species of bamboo grown at different locations
indicated that Dendrocalainus harboured maximum number of total
bacteria and N2-fixers whereas Bambusa arundinaceae recorded highest
number of P-solubilizers and Bambusa recorded highest population
of fungi and actinomycetes. Bamboo plants grown in medium black soil
showed higher population of different groups of microorganisms than those
grown in red soils. Out of 32 representative major bacterial isolates
obtained from bamboo rhizosphere, 16 were found to be N^-fixers, six
were P-solubilizers and 10 were predominant general bacterial isolates. The
N,-fixers mainly belonged to the genera Azotobacter Azospirillum. The
P-solubilizers belonged to Pseudomonas, Xanthomonas and Erwinia.
Predominant bacterial isolates belonged to Bacillus, Erwinia, Pseudomonas
and Xanthomonas.
Among N2-fixers, Azospirillum isolates were found to fix higher amount
of nitrogen than Azotobacter isolates. In case of P-solubilizers, strains
PSER-1 and PSER-2 showed maximum solubilization of tricalcium phosphate
with maximum reduction in pH of the broth. All N2-fixers and P-solubilizers
were found to produce lAA and GA. Inoculation of bamboo seeds with selected
efficient nitrogen fixers or P-solubilizers either individually or in combination
showed increased growth of bamboo seedlings. In general single inoculation
treatments gave better results than combined inoculations. All the
inoculation treatments enhanced the seed germination root and shoot length
as well as dry matter accumulation of bamboo seedlings.
The microbial load and enzyme activities in soil under leaf litter of
bamboo were significantly higher than that of control soil (unplanted soil).
Among the bamboo plant densities, the soil under highest plant density
showed maximum population of bacteria, fungi, actinomycetes, N2-fixers,
P-solubilizers and cellulose degraders, as well as dehydrogenase, urease and
phosphatase activities.
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