Potential of Rhizobacteria for Promotion of Sorghum Growth and Suppression of Striga Development
Lenard Mounde, Michael Yongha Boh, Marc Cotter, Joachim Sauerborn
University of Hohenheim, Inst. of Plant Production and Agroecology in the Tropics and Subtropics, Germany
The objective of this study was to screen the potential of four rhizobacteria strains for growth promotion in sorghum (Sorghum bicolor) and suppression of Striga hermonthica development. Plant growth promoting rhizobacteria (PGPR) Bacillus subtilis Bsn5, B. subtilis GBO3, B. amyloliquefaciens FZB42 and Burkholderia phytofirmans PsJN were evaluated under controlled environmental conditions in a growth chamber. Two day-old sorghum seedlings and preconditioned Striga hermonthica seeds were placed in fiber glass filter papers (20×6 cm length and width and respectively) between a transparent plexiglas lid and a PVC root chamber (20×6×2cm length, width and depth, respectively) , allowing the observation of sorghum roots and the Striga underground stages. The chambers were filled with sterilized sand. Each plant received prepared PGPR inoculum according to treatments. Blank ringer solution was used as control. The effect of PGPR on sorghum plant height, SPAD chlorophyll value, dry biomass yield, Striga germination, attachment and tubercle development was analysed after 28 days. Sorghum plants treated with PGPR were significantly (p<0.05) taller with relatively higher SPAD chlorophyll values and dry biomass yield in the controlled treatment compared to the treatments where Striga as root parasite was added. Compared to the control treatment, Striga seed germination was by 18 and 14 % significantly lower in the B. subtilis GBO3- and B. amyloliquefaciens FZB42-treated plants, respectively. Of the germinated Striga seeds, the percentage that attached to the sorghum plant was least (23 %) in the B. subtilis GBO3-treatment compared to all other treatments. Striga tubercle death percentages in PGPR treatments ranged between 35 and 59% compared to <3% in control plants. This study identified B. subtilis GBO3, and B. amyloliquefaciens FZB42) and Burkholderia phytofirmans PsJN as having the highest potential in both sorghum growth promotion and Striga suppression abilities. It is recommended their mechanisms of growth promotion and Striga suppression be investigated in future studies.
Keywords: Biological, host-parasite interaction, hyperparasite, plant growth promoting rhizobacteria, weed control
Contact Address: Lenard Mounde, University of Hohenheim, Inst. of Plant Production and Agroecology in the Tropics and Subtropics, Garbenstrasse 13, Stuttgart, Germany, e-mail: moundel05yahoo.com