Page 2 Plant-Bacteria Interactions Edited by Iqbal Ahmad, John ...

270j 14 Salt-Tolerant Rhizobacteria: Plant Growth Promoting Traits
Table 14.8 Effects of A. chrococcum A2 on crop yields in saline soils of Uzbekistan.
Cotton
Treatments Yield (t ha 1 ) Fiber (%)
Wheat yield
(t ha 1 )
Rice yield
(t ha 1 )
Control 2.95b 32a 2.8b 4b 16b
A. chrococcum A2 3.52a 35a 3.5a 4.6a 20a
Potato yield
(t ha 1 )
Mean values followed by the different lower case letters in the same column were significantly
different at P 0.05.
significantly increased shoot growth and root length (10–43%) of wheat and peas in
saline soils compared to the control treatment [15,113] (Table 14.9).
It is postulated that salt-tolerant bacteria that are adapted to saline and drought
condition will develop a beneficial association with plants and are expected to
produce growth-promoting substances as evidenced by the increase in plant dry
matter production, yield and nutrient uptake. It is reported that Pseudomonas strains
significantly enhance early plant growth in low-fertility soil [62]. Although bacterial
inoculation marginally increased crop yields when planted under ideal climatic and
soil conditions, greatest benefits in terms of improved plant growth and yield were
obtained when crops encountered periods of environmental stress [114]. The beneficial
effects of Pseudomonas strains (e.g. P. fluorescens ANP15 and P. aeruginosa
7NSK2) on plant growth were found more pronounced when plants were subjected
to suboptimal conditions, such as an unfavorable climate or the presence of plant
pathogens [115].
A number of bacterial strains isolated from degraded soils were found to be
stimulants for wheat and rice growth in warm climates [116]. To obtain most
competitive and effective bacterial strains, bacteria need be isolated and screened
from the pool of indigenous microbes that supposedly are versatile to adapt to a wide
range of climatic conditions [117]. In particular, the rhizobia isolated from nodules
Table 14.9 Effects of growth-promoting bacteria on relative
growth (%) of shoot and root of wheat and peas.
Wheat Peas
Bacterial strains Shoot Root Shoot Root
Control 100c 100d 100c 100e
P. alcaligenes PsA15 116b 125b 125a 135a
B. amyloliquefaciens BcA12 143a 137a 127a 124b
B. polymyxa BcP26 115b 119b 111b 118b
A. simplex ArS7 138a 135a 121a 134a
A. globiformis ArG1 110b 106d 108c 107d
M. phlei MbP18 113b 116c 116b 112c
Mean values followed by the different lower case letters in the same column were significantly
different at P 0.05.