Variable responses on early development of shallot (Allium ascalonicum) and mustard (Brassica juncea) plants to Bacillus cereus inoculation

• Main Authors: Ab. Aziz, Zakry Fitri, Mohd Saud, Halimi, Abdul Rahim, Khairuddin, Ahmed, Osumanu Haruna
• Format: Article
• Language: English
• Published: Malaysian Society for Microbiology 2012
• Online Access: http://psasir.upm.edu.my/id/eprint/63947/1/Variable%20responses%20on%20early%20development%20of%20shallot%20%28Allium%20ascalonicum%29%20and%20mustard%20%28Brassica%20juncea%29%20plants%20to%20Bacillus%20cereus%20inoculation.pdf; http://psasir.upm.edu.my/id/eprint/63947/; http://mjm.usm.my/index.php?r=cms/entry/view&id=51

Aim: Auxin, a phytohormone secreted by plant growth-promoting rhizobacteria is one of the direct mechanisms vital for plant growth promotion. A laboratory experiment was conducted to observe the effect of IAA-producing and non-IAA-producing diazotroph Bacillus cereus strains on early growth of shallot (Allium ascalonicum) and mustard (Brassica juncea) plants. Methodology and Results: Treatments evaluated were as follows: Control = uninoculated, no inoculation, UPMLH1 = IAA-producing B. cereus UPMLH1, and UPMLH24 = non-IAA-producing B. cereus UPMLH24. Inoculation with IAA-producing B. cereus UPMLH1 significantly increased shallot adventitious roots (root number and length) and shoot growth (19 to 54% increment). Inoculation of non-IAA-producing B. cereus UPMLH24 did not significantly improve growth of adventitious roots of shallot as compared to uninoculated control, except its shoot (up to 40% increase). However, primary roots and shoot growth of mustard plants significantly increased through inoculation with IAA-producing and non-IAA-producing strains (14 to 73% increment). Conclusion, Significance and Impact of Study: The results indicated that exogenous IAA secreted by B. cereus UPMLH1 might have play an important role in inducing roots of shallot bulbs and it may have a variable promotional effect depending on plant species.