Plant growth promoting rhizobacteria (PGPR) for improving growth and yield of wheat

In order to evaluate the potential of rhizobacteria for enhancing growth and yield of wheat crop under optimum fertilizer application, field experiments were conducted at two different sites (Post graduate Agriculture Research Station, Jhang Road, Faisalabad and in the Research Area, Deptt. of Soil Science, University of Agriculture Faisalabad) during the year 1999- 2000. Four different rhizobacterial isolates were used for seed inoculation. Treatments with four replications were compared in randomized complete block design. The soil samples were collected from 0-15 cm depth, air-dried, mixed thoroughly, passed through 2.0 mm sieve and analyzed for different physical and chemical characteristics before sowing. Fertilizer doses were applied at the rate of 120-75-50 Kg NPK ha-1 as urea, SSP ans SOP, respectively. Four wheat varieties (Pasban 90, Inqlab 91, Watan 93 and Pb96) were sown in separate fields and canal water was used for irrigation. Spike length and number of spike lets per spike were recorded at maturity while 1000-grain weight, straw and grain yield were recorded after harvest. The data obtained were analyzed statistically. The results are summarized as below. Results regarding grain yield showed a significant increase at both the experimental sites. In our study at research area of university, rhizobacterial strain W9 significantly increased the grain yield of Pasban 90 (19.5%), Inqlab 91 (3.4%) and Punjab 96 (24.3%) while W11 produced 31.7% higher grain yield in case of Watan 93. At PARS, the grain yield was increased significantly by W 11 (4.0%), W29 (6.8%), and W 14 (4.8%) in case of Pasban 90, Inqlab 91 and Watan 93, respectively. Results of the trials conducted at research area of the University, isolate W11 enhanced the straw yield, 1000-grain weight, plant height and number of tillers by 13.1, 8.9, 11.8 and 13.4%, respectively, in case of Watan 93. Isolate W9 was found to be most consistent and increased growth parameters, significantly over control in remaining three selected varieties of wheat. The maximum increase in straw yield, 1000-grain weight, plant height and number of tillers due to inoculation with W9 were 32.9, 2.8, 2.2 and 37.6%, respectively, for remaining three varieties. In our trials conducted at PARS, Isolate W9 significantly increased the 1000-grain weight (17.6%) and plant height (6.5%), while W14 was effective in enhancing straw yield (20.9%) and number of tillers (22.5%). Isolate W29 significantly increased the straw yield (9.5%), plant height (6.8%), number of tillers (7.4%) and number of spikelets spike-1 (21.2%) in case of Inqlab 91. Isolate W14 increased the straw yield, 1000-grain weight, plant height and number of tillers by 28.7, 1.1, 4.8 and 27.9%, respectively, in case of Watan 93. Isolate W9 performed well with all the four varieties except Watan 93 in research area of university while isolate W14 remained consistent for Pasban 90 and Watan 93 in PARS. Our studies clearly demonstrated that potential of plant growth promoting rhizobacteria for enhancing the yields agricultural crops as we observed significant yield increase of wheat in response to inoculation. However, the effects were variety specific. In general, isolate W9 produced promising results at university and isolate W14 was more consistent at PARS.