Influence of nitrogen fixing and phosphorus solubilizing bacteria on the nodulation, plant growth, and yield of chickpea

Drawbacks of intensive farming practices and environmental costs of nitrogen (N) and phosphorus (P) fertilizers have renewed interest in biofertilizers. A study was conducted in order to investigate seed inoculation of chickpea with Rhizobium, N2-fixing Bacillus subtilis (OSU-142) and P-solubilizing Bacillus megaterium (M-3) in comparison to control and mineral fertilizer application in controlled environment and in field conditions in 2003 and 2004 in Erzurum (29 degrees 55' N and 41 degrees 16' E with an altitude of 1950 m), Turkey. In the controlled environment and in the field trials, single, dual, and triple inoculations with Rhizobium, OSU-142, and M-3 significantly increased all the parameters investigated (plant height, shoot, root and nodule dry weight, N%, chlorophyll content, pod number, seed yield, total biomass yield, and seed protein content) compared with the control treatment, equal to or higher than N, P, and NP treatments. In the field all the combined treatments containing Rhizobium were better for nodulation than the use of Rhizobium alone. However, nodulation by native soil Rhizobium population was increased in single and dual inoculations of OSU-142 and M-3. Significant increases of the seed yield under different inoculation treatments ranged between by 18.0% (Rhizobium) and 30.5% (Rhizobium + OSU-142 + M-3) over the control whereas N, P, and NP applications corresponded to increases of 27.0%, 11.1%, and 33.1%, respectively. In general, the increases in seed and total biomass yields were more pronounced in dual and triple inoculations. In conclusion, seed inoculation with Rhizobium, Bacillus subtilis and Bacillus megaterium, especially dual and triple combinations, may substitute costly NP fertilizers in chickpea production even in cold highland areas such as in Erzurum.