Abstract

Locally isolated Bacillus subtilis (UPMB10) as nitrogen fixer and B. pumillus (GM118) as phosphate solubilizer act as plant growth promoting rhizobacteria (PGPR). The objective of this study is to determine the response of single and co-inoculation of these PGPR on the panicle breaking strength to minimize panicle grain shattering to increase rice yield.  The ability to fix nitrogen and solubilize phosphate, production of indole-3-acetic acid (IAA) and grain yield production of single and co-inoculants of PGPR were studied. The result demonstrated that single and combined inoculations were able to fix nitrogen and solubilize phosphate. Besides, the ability of UPMB10 and mix inoculation to produce high concentration of IAA enables them to provide a high breaking force needed to detach grain from panicle compared to GM118 and in turn increase the rice grain yield. Hence, this study showed the potential single and combined inoculations as a biofertilizer to increase rice productivity in the granary areas of Malaysia.

Key words: Plant growth promoting rhizobacteria (PGPR), co-inoculation, Bacillus, indole-3-acetic acid (IAA), grain shattering, yield, Oryza sativa L.