New way to boost soybean yield may help feed the world: study

Researchers have developed a novel way to dramatically increase the yield and quality of soybeans, a breakthrough that may help address society's challenge of feeding a growing human population while protecting the environment.
Mechthild Tegeder from the Washington State University in the US, designed a new way to increase the flow of nitrogen, an essential nutrient, from specialised bacteria in soybean root nodules to the seed-producing organs.
Researchers found the increased rate of nitrogen transport kicked the plants into overdrive.
Their greenhouse-grown soybean plants fix twice as much nitrogen from the atmosphere as their natural counterparts, grow larger and produce up to 36 per cent more seeds.

"The biggest implication of our research is that by ramping up the natural nitrogen allocation process we can increase the amount of food we produce without contributing to further agricultural pollution," Tegeder said.
"Eventually we would like to transfer what we have learned to other legumes and plants that humans grow for food," she said.

Legumes account for around 30 per cent of the world's agricultural production. They consist of plants like soybeans, alfalfa, peas, beans and lentils, among others.
Unlike crops that rely on naturally occurring and artificially made nitrogen from the soil, legumes contain rhizobia bacterioids in their root nodules that have the unique capability of "fixing" nitrogen gas from atmosphere.

For years, scientists have tried to increase the rate of nitrogen fixation in legumes by altering rhizobia bacterioid function or interactions that take place between the bacterioid and the root nodule cells.
Tegeder increased the number of proteins that help move nitrogen from the rhizobia bacteria to the plant's leaves, seed-producing organs and to parts where it is needed.
The additional transport proteins sped up the overall export of nitrogen from the root nodules. This initiated a feedback loop that caused the rhizobia to start fixing more atmospheric nitrogen, which the plant then used to produce more seeds.
"They are bigger, grow faster and generally look better than natural soybean plants. Some evidence we have suggests they might also be highly efficient under stressful conditions like drought," Tegeder said.

Nitrogen is a macronutrient essential for plant growth. Large amounts of synthetic nitrogen fertiliser are applied around the world to ensure high plant productivity.
Application is an environmental issue in industrialised countries because of high energy input, increased greenhouse gas emissions, water pollution and other adverse effects on ecosystems and human health.
The study was published in the journal Current Biology.