Evaluation of the effects of Plant Growth Promoting Rhizobacteria and salinity on germination and growth of corn plants (Zea mays L.)

The plant promoting bacteria as biological fertilizers play an important role in increasing productivity and improving plant growth in stress condition. In order to evaluate the ability of plant promoting bacteria rhizobacteria on germination and growth of corn under salinity conditions, a pot experiment was conducted in factorial based on randomized complete block design with three replications. The treatments consisted of salinity stress at five levels [zero (control), 2, 4, 6 and 8 dSm-1 of sodium chloride] and four levels of bacterial [non-inoculation (control), Azotobacter chroococum, Pseudomonas fluorescens and Pseudomonas putida]. The Results showed a significant effect (p <0.01) on maximum germination, germination uniformity, time to 10% and 90% germination due to salinity stress. The most Gmax and D10 values were obtained in Azotobacter chroococum bacteria treatment. The interaction effects of salinity stress and bacterial inoculation significantly affected the Gmax values. Bacterial inoculation increased Gmax values significantly compared to non-inoculation plants in all of salinity levels. Also salinity stress effect was significant (P<0.01) for biomass, root weight, leaf number and height of corn. The most biomass yield and plant height were obtained from the inoculation with Azotobacter chroococum. Results showed that biomass yield and plant height decreased with increasing salinity stress in non-inoculated treatments. Inoculation with bacteria increased the biomass and height of plant significantly compared to non-inoculated plants in all of salinity levels. Based on our results, PGPRs can alleviate the negative-effects of salinity stress in corn through increasing of plant growth.