The naturally occurring bacteria can prevent buildup of the plant stress hormone ethylene, which retards growth. The research found their presence increased plant mass by up to 25 per cent, especially in dry conditions when ethylene is more prevalent.
"This has been shown over a range of plants," plant biologist Professor Bill Davies told the BPOA technical seminar. "And you can isolate the bacteria easily and cheaply."
He added: "You get a significant increase in water use efficiency - crop per drop. One of the promising directions for this is in deficit irrigation, which is important in the context of climate change."
Trials on Arabidopsis showed that application of the rhizobacterium Variovorax paradoxus also yielded earlier and more flowers relative to leaf growth.