A recent spate of crop biotech breakthroughs presage a New Green Revolution that will boost crop production, shrink agriculture's environmental footprint, help us weather future climate change, and provide better nutrition for the world's growing population.
The first Green Revolution was generated through the crop breeding successes pioneered by agronomist Norman Borlaug back in the 1960s. The high-yielding dwarf wheat varieties bred by Borlaug and his team more than doubled grain yields. The Green Revolution averted the global famines confidently predicted for the 1970s by population doomsters like Stanford entomologist Paul Ehrlich. Other crop breeders using Borlaug's insights boosted yields for other staple grains. Since 1961, global cereal production has increased 400 percent while the world population grew by 260 percent. Borlaug was awarded the Nobel Peace Prize in 1970 for his accomplishments. Of course, the disruptions of the COVID-19 pandemic and Russia's invasion of Ukraine are currently roiling grain and fertilizer supplies.
Borlaug needed 20 years of painstaking crossbreeding to develop his high-yield and disease-resistant wheat varieties. Today, crop breeders are taking advantage of the tools of modern biotechnology that can dramatically increase the rate at which yields increase and drought- and disease-resistance can be imbued in crops.
The Green Revolution's crops required increased fertilizer applications to achieve their higher yields. However, fertilizers have some ecologically deleterious side effects. For example, the surface runoff of nitrogen and other fertilizers not absorbed by crops spurs the growth of harmful alga in rivers, lakes, and coastal areas. In addition, excess nitrogen fertilizer gets broken down by soil bacteria such that there are rising atmospheric concentrations of the greenhouse gas nitrous oxide, which, pound for pound, has 300 times the global warming potential of carbon dioxide.
The good news is that in the last month, two teams of modern plant breeders have made breakthroughs that will dramatically cut the amount of nitrogen fertilizers crops need for grain production. In July, Chinese researchers reported the development of "supercharged" rice and wheat crops, which they achieved by doubling the expression of a regulatory gene that increases nitrogen uptake by four- to fivefold and enhances photosynthesis. In field trials, the yields of the modified rice were 40 to 70 percent higher than those of the conventional varieties. One upshot is that farmers can grow more food on less land using fewer costly inputs.
Some crops like soybeans and alfalfa get most of the nitrogen fertilizer they need through their symbiotic relationship with nitrogen-fixing soil bacteria. Soybeans supply the bacteria living on their roots with sugars, and the bacteria in turn take nitrogen from the air and turn it into nitrate and ammonia fertilizers for the plants. However, nitrogen-fixing bacteria do not colonize the roots of cereal crops.
A team of researchers associated with the University of California Davis reported in July their success in gene editing rice varieties to make their roots hospitable to nitrogen-fixing bacteria. As a result, when grown under conditions of limited soil nitrogen, the yields of the gene-edited varieties were 20 to 35 percent higher than those of the conventional varieties. The researchers believe their gene-editing techniques can be applied to other cereal crops.
This new biotech-enabled Green Revolution promises a future in which more food from higher yields grown using less fertilizer means more farmland restored to nature, less water pollution, and reduced greenhouse gas emissions.
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