In a finding that could have significant implications for agriculture worldwide, researchers report that spraying crops with methanol greatly increases yields and reduces the amount of water the plants need.
A single treatment with the inexpensive chemical increases the efficiency with which the plants convert carbon dioxide into sugars and shrinks pores in the foliage to reduce unnecessary evaporation of water, researchers in San Diego and Phoenix report today in the prestigious Proceedings of the National Academy of Sciences.
Cotton grown in Arizona, for example, required only one-third the water used in neighboring fields, said biochemist Andrew A. Benson of the Scripps Institution of Oceanography, while watermelons, cabbages and some other produce grew twice as large as normal.
The new approach, which has been partially replicated by other researchers, has the potential to revolutionize agriculture in arid regions of the world, Benson said.
The report "opens some very exciting possibilities," said biologist James A. Bassham of the Lawrence Berkeley Laboratory, one of few researchers familiar with the work. "I don't doubt the results, but it will require much more testing and much more investigation to prove them out. If they are true, this is a very significant development."
The results are so promising that Benson's colleague, botanist Arthur M. Nonomura, said he is incorporating the technique on virtually all the crops that he raises on his Arizona farm.
But the treatment does not work with all crops and under all conditions, Nonomura said. Methanol treatment benefits only crops classified by botanists as C3, a broad group of relatively inefficient plants that includes tomatoes, palms, roses, wheat, strawberries and melons, as well as cotton and watermelons.
It is not effective for so-called C4 plants, a category of more efficient plants that includes corn, sorghum and many noxious weeds. The technique also does not work for crops grown in shade or in winter.
The work is an outgrowth of studies performed by Nonomura, who is now a full-time farmer, while he was at Scripps in the early 1980s.
He and Benson, a highly respected scientist who has been working on photosynthesis for more than four decades, found that adding methanol to algae's nutrients doubled its growth rate. "But the price of petroleum dropped by half, so we abandoned the project," Nonomura said.
Benson continued biochemical work and plans to report in a series of forthcoming papers that the methanol makes the metabolism of C3 plants resemble that of the more efficient C4 plants. But it is not clear, he said, why the effect persists for extended periods.
Nonomura has so far grown 1,000 acres of methanol-treated cotton on his farm in Litchfield Park, near Phoenix.
He found that it needed watering every nine days, compared to every seven days for untreated plants. The treated cotton also matured 15 days earlier than untreated cotton, further reducing water use.
Methanol is a natural byproduct of plant metabolism that is converted into sugars. In the form sprayed on crops it poses no danger to humans.