Agriculture Reference
In-Depth Information
to the dilution effects from the P solubilized by the PSB. Thus, this decreased
the
32
P activity, as compared to the control, where no P was solubilized from the
added PR.
9.4.2 Effect of PSB on Grain Yield
A synergistic effect on aerobic rice in this study was observed which enhanced the P
uptake and plant biomass production. In a similar study, Barea et al. (
2003
) also
found an identical trend in plants P uptake following inoculation of PSB while
P. putida
inoculation enhanced the growth of canola (Lifshitz et al.
1987
). Since the
production of IAA by PSB has a positive effect on root architecture (Naher
et al.
2009
), therefore, an extensive root system improves the nutrient uptake
from the surroundings leading to the higher plant biomass production. The IAA
exudation can further increase the carbon fixation through increased nutrient
uptake. Moreover, inoculation with PSB, for example,
Azospirillum lipoferum
34H, has reported to improve rice seeds P ion content and consequently improved
root length and fresh and dry shoot biomass (Murty and Ladha
1988
). Concurrently,
increases in P uptake and crop yields have been observed after PSB inoculation
with
Bacillus
sp. (Panhwar et al.
2013
),
Pseudomonads
, and
Bacilli
(Sharma
et al.
2013
). Inoculation of PSB enhanced P uptake and simultaneously increased
the yield of aerobic rice. Plant P uptake, P use efficiency (PUE %), total biomass,
and total protein content increased with the inoculation of PSB with CIPR and
OA. In addition, PSB inoculation and the application of PR and OA significantly
increased the grain yield and plant biomass of aerobic rice (Table
9.6
). The highest
grain yield and plant biomass were determined when PSB was inoculated with
CIPR and OA and was statistically at par with those of PSB and PR application
(Panhwar et al.
2013
).
9.5 Conclusion
The phosphate-solubilizing bacteria have generally been found effective for
enhancing the bioavailable P by several mechanisms, such as production of organic
acids, ammonium assimilation, or enzyme production. In the acidic soil, P is mostly
bound with Fe/Al and in alkaline soil with Ca. Moreover, phosphate-solubilizing
bacteria are widely distributed in different soil-plant ecosystem and perform a
major role in soil organic and inorganic P solubilization. The inoculation of PSB
solubilization/mineralization endowed with phytohormone-producing ability is
likely to have a synergistic and productive effect, which might increase P uptake,
growth and yield of various crops including aerobic rice.
