Effects of plant growth promoting rhizobacteria (PGPR) on yield,growth and nutrient contents in organically growing raspberry

Summary

During 2003 and 2005, plant growth promoting effects of two Bacillus strains OSU-142 (N2-fixing) and M3 (N2-fixing and phosphate
solubilizing) were tested alone or in combinations on organically grown primocane fruiting raspberry (cv. Heritage) plants in terms of yield,
growth, nutrient composition of leaves and variation of soil nutrient element composition in the province of Erzurum, Turkey. The results showed
that Bacillus M3 treatment stimulated plant growth and resulted in significant yield increase. Inoculation of raspberry plant roots and rhizosphere
with M3 and/or OSU-142 + M3, significantly increased yield (33.9% and 74.9%), cane length (13.6% and 15.0%), number of cluster per cane
(25.4% and 28.7%) and number of berries per cane (25.1% and 36.0%) compared with the control, respectively. In addition, N, P and Ca contents of
raspberry leaves with OSU-142 + M3 treatment, and Fe and Mn contents of the leaves of raspberry with M3 and OSU-142 + M3 applications
significantly improved under organic growing conditions. Bacterial applications also significantly effected soil total N, available P, K, Ca, Mg, Fe,
Mn, Zn contents and pH. Available P contents in soil was determined to be increased from 1.55 kg P2O5/da at the beginning of the study to
2.83 kg P2O5/da by OSU-142, to 5.36 kg P2O5/da by M3 and to 4.71 kg P2O5/da by OSU-142 + M3 treatments. The results of this study suggest
that Bacillus M3 alone or in combination with Bacillus OSU-142 have the potential to increase the yield, growth and nutrition of raspberry plant
under organic growing conditions.