Isolation, Screening and Response of Maize to Plant Growth Promoting Rhizobacteria Inoculants

Abstract The use of plant growth promoting rhizobacteria (PGPR) as biofertilizer is a relatively safer, environment friendly and cost effective. This work was designed to assess plant growth promoting abilities of rhizobacteria and evaluate their effect on germination and growth of maize. The bacteria were isolated and screened for plant growth promoting abilities using Pikovskaya agar, Aleksandrov agar and Jensen media. Twelve isolates that showed multiple attributes were further screened for indole acetic acid (IAA) and gibberellic acid (GA) production; best five isolates were selected for further studies. The results of IAA and GA production showed a considerable amount of IAA and GA produced by the isolates which ranged between 9–94 and 21–97 mg l–1, respectively. The selected isolates identified as Bacillusmojavensis, Pseudomonas aeruginosa, Alcaligenes faecalis, Pseudomonas syringae and Bacillus cereus showed a significant difference(P≤0.05) in the amount of potassium(K) and phosphorus(P) solubilized at different source of K (KCl and mica powder) and P (Ca2PO4 and rock phosphate). The isolates also recorded significant level of nitrogen fixing ability with Alcaligenes faecalis strain P156 fixing the highest amount of nitrogen (11.4 mg N fixed per l) and least by Bacillus mojavensis strain NBSL51 (6.3 mg N fixed per l).The results of plant inoculation test showed that Bacillus cereus strain 20UPMNR significantly enhanced the root and shoot dry weight. All the selected isolates enhanced shoot and root length except Bacillus mojavensis which produced less effect on root length when compared to the control. These results have provided vital information for the development of a bio fertilizer for maize.