Inoculation effects of isolated plant growth promoting bacteria on wheat yield and grain N content

PGPB play an important role in agricultural systems, and contain broad range of bacterial genera. Therefore, in this study, seeds of wheat were inoculated with 18 rhizobacteria strains belonging to Azotobacter chroococcum (14SPI, 44SP-2, 16SP-2, 14SP2-1), Pseudomonas sp. (24A-1, 34A-2, 34SPIII, 35SP-2), Agrobacterium sp. (14A-4, 22SP-1), Rhizobium sp. (12A-3), Sphingomonas sp. (37SP), Stenotrophomonas sp. (16SP7-2), Citrobacter sp. (44 A-4S), Achromobacter sp. (14SPIII), Klebsiella oxytoca (4A-1), Beijerinckia sp. (2SP-5) and 36 A-2L isolate, to determine the effects on growth and yield of spring wheat under greenhouse condition. In this study, 18 carrier-based PGPB treatments along with one negative (B0: no inoculation) and two positive controls (B0N50 and B0N100; containing 50% and 100% of urea fertilizer, respectively) were used. The results showed that inoculation treatments had no significant effect on some plant parameters (e.g., chlorophyll index, spike length) compared with the B0, but revealed significant differences (p < .01) in other parameters such as seed weight, seed number, total dry weight, and N uptake of grain. B0N100, B0N50, and 14A-4 significantly enhanced the total dry weight (shoot, root, spike, and leave) by 35%, 32.4%, and 28.5% as compared to the control, respectively. These trends were observed in seed number and seed weight, too. Highest content of grain N uptake and Zn uptake were in 14SPI, content of P was in 44SP-2, and K and Fe content were achieved in 16SP-2 and 14SPI. In general, Agrobacterium sp. 14A-4, A. chroococcum (14SP-I, 16SP-2, and 44SP-2) were effective isolates to improve qualitative and quantitative traits of wheat.

Automated summary

PGPB play an important role in agricultural systems, containing a broad range of bacterial genera. In this study, wheat seeds were inoculated with different strains of PGPB, which showed significant effects on the growth and yield of wheat, particularly in terms of seed number, seed weight, total dry weight, and nutrient uptake.