Effects of plant growth promoting bacteria (PGPB) on yield, growth and nutrient contents of organically grown strawberry

Summary

The effects of plant growth promoting bacteria (PGPB) on the fruit yield, growth and nutrient element
content of strawberry cv. Fern were investigated under organic growing conditions between 2006 and
2008. The experimental plot was a completely randomized design with 3 replicates. Three PGPB strains
(Pseudomonas BA-8, Bacillus OSU-142 and Bacillus M-3) were used alone or in combination as biofertilizer
agent in the experiment. Data through 3 years showed that the use of PGPB significantly
increased fruit yield, plant growth and leaf P and Zn contents. Root inoculation of M3 and floral and foliar
spraying of OSU-142 and BA-8 bacteria stimulated plant growth resulting in significant yield increases.
M3 + BA-8, BA-8 + OSU-142, M3, M3 + OSU-142 and BA-8 applications increased cumulative yield by
33.2%, 18.4%, 18.2%, 15.3% and 10.5%, respectively. Number of fruits per plant significantly increased by
the applications of M3 + BA-8 (91.73) and M3 (81.58) compared with the control (68.66). In addition, P
and Zn contents of strawberry leaves with bacterial inoculation significantly increased under organic
growing conditions. Available P contents in soil were increased from 0.35 kg P2O5/da at the beginning of
the study to 2.00, 1.97 and 1.82 kg P2O5/da by M3 + OSU-142, M3 + BA-8 and M3 + BA-8 + OSU-142
applications, respectively. Overall, the results of this study suggest that root inoculation of Bacillus M3
alone or in combination with spraying Bacillus OSU-142 or Pseudomonas BA-8 have the potential to
increase the yield, growth and nutrition content of strawberry plant under organic growing conditions.