Abstract:
Inorganic phosphate solubilization by
phosphate solubilizing bacteria (PSB) is
known to be one of the major mechanisms
associated with plant growth promotion.
The use of plant growth-promoting
bacteria as bio-inoculants/bio-fertilizers
is thus considered to be an
environmentally friendly approach of soil
enrichment. Fifteen PSB from different
agricultural lands including terrestrial,
aqua and swamp regions of Southern Sri
Lanka were isolated using serial dilution
plating on NBRIP agar plates and
screened for various plant growth promoting traits. The highest phosphate
solubilization (1127 µg/ml) was exhibited
in PSB-14 which was identified as
Enterobacter sp. IAA production was
detected by 6 strains and among them,
bacterial isolate PSB-12 showed the
highest IAA production (24.2 µg/ml)
followed by PSB-7 and PSB-1 (21.3 and
20.9 µg/ml respectively). Except for PSB-8and PSB-13 strains, all the other isolated
strains showed a positive response for
ammonia production. Except for PSB-2,
PSB-7, PSB-10 and PSB-11, all the other
studied isolates showed HCN production.
PSB-3, PSB-9 and PSB-14 isolates were
found to be strong HCN producers. All
the strains showed catalase activity
implying that they were capable of
growing under stress conditions. PSB-1,
PSB-12, PSB-14 and PSB-15 strains
showed all the tested plant growth
promotion traits.
