Effects Of Plant Growth-Promoting Rhizobacteria And Biocontrol Bacteria Isolated From Kavango On Pennisetum Glaucum And Sorghum Bicolor

Abstract

As a result of the ever increasing population growth, the demand on food is expected to rise significantly. In order to meet this increase in food demand, alternatives (PGPR and biocontrol bacteria) to environmentally damaging chemical augmenters can be utilized for the production of agricultural crops. This study was conducted to isolate and screen rhizospheric bacteria from grasses along the Kavango River for plant growth promoting and biocontrol abilities. Once validated, bacteria possessing these abilities were used as peat-based inoculants to evaluate their effects on the growth of Pennisetum glaucum and Sorghum bicolor. The bacteria were isolated from rhizospheres of P. australis, Sporobolus sp., V. nigritana, P. glaucum, S. bicolor and a grass known locally as ngwena. The isolates were screened for NH3 production, protease activity, phosphate solubilisation, siderophore production, indole-3-acetic acid production, nifH-gene presence and antifungal-activity. Up to 14 bacteria considered as possessing plant growth enhancing (11) or biocontrol (3) traits were isolated from grasses located at Mashare and surrounding areas. The majority of the isolates exhibited more than one trait and were classified as follows; 3 phosphate solubilizers, 4 siderophore producers, 8 IAA producing isolates, 5 N2-fixers, and 3 isolates with antifungal-activity. S. maltophilia LCS2-11 as single treatment and in combination treatment with B. amyloliquefaciens LSM1-61 and P. stutzeri ACM2-32, enhanced P. glaucum biomass statistically similarly to the commercial fertilizer’s growth effects. The combination treatment T9 (B. amyloliquefaciens LSM1-61: E. cloacae FCM2-50: P. stutzeri ACM2-32) enhanced S. bicolor biomass significantly (p = 0.032) compared to the water control.