Plants get a growth boost from doses (small ones) of hydrogen sulfide

A bean plant treated with hydrogen sulfide (top) is substantially bigger at two weeks after gestation than the control plant (bottom) that was untreated.

A bean plant treated with hydrogen sulfide (top) is substantially bigger at two weeks after gestation than the control plant (bottom) that was untreated.

Low doses of hydrogen sulfide, the pungent stuff often referred to as sewer gas, could greatly enhance plant growth, leading to a sharp increase in global food supplies and plentiful stock for biofuel production, new University of Washington research shows.

Frederick Dooley, a UW doctoral student in biology who led the research, said (here) he started off to examine the toxic effects of hydrogen sulfide on plants but mistakenly used only one-tenth the amount of the toxin he had intended.

The results were so unbelievable that he repeated the experiment.

Still unconvinced, he repeated it again – and again, and again.

In fact, the results have been replicated so often that they are now “a near certainty,” he said.

“Everything else that’s ever been done on plants was looking at hydrogen sulfide in high concentrations,” he said.

The research is published online (here) in PLOS ONE, a Public Library of Science journal.

The abstract says:

This study presents a novel way of enhancing plant growth through the use of a non-petroleum based product. We report here that exposing either roots or seeds of multicellular plants to extremely low concentrations of dissolved hydrogen sulfide at any stage of life causes statistically significant increases in biomass including higher fruit yield.

Individual cells in treated plants were smaller (~13%) than those of controls. Germination success and seedling size increased in, bean, corn, wheat, and pea seeds while time to germination decreases. These findings indicated an important role of H2S as a signaling molecule that can increase the growth rate of all species yet tested.

The increased crop yields reported here has the potential to effect the world’s agricultural output.

The University of Washington media release says at high concentrations – levels of 30 to 100 parts per million in water – hydrogen sulfide can be lethal to humans.

At one part per million it emits a telltale rotten-egg smell.

Dooley used a concentration of 1 part per billion or less to water seeds of peas, beans and wheat on a weekly basis. Treating the seeds less often reduced the effect, and watering more often typically killed them.

A time-lapse video shows how a seed of dwarf wheat treated with a low dose of hydrogen sulfide begins growing at an accelerated rate compared with an untreated seed.

With wheat, all the seeds germinated in one to two days instead of four or five, and with peas and beans the typical 40 percent rate of germination rose to 60 to 70 percent.

“They germinate faster and they produce roots and leaves faster. Basically what we’ve done is accelerate the entire plant process,” he said.

Crop yields nearly doubled, said Peter Ward, Dooley’s doctoral adviser, a UW professor of biology and of Earth and space sciences and an authority on Earth’s mass extinctions.

Hydrogen sulfide, probably produced when sulfates in the oceans were decomposed by sulfur bacteria, is believed to have played a significant role in several extinction events, in particular the “Great Dying” at the end of the Permian period.

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