There are more than 120,000 varieties of rice stored at the germplasm bank at the International Rice Research Institute (IRRI) in the Philippines, but a new paper focused on varieties that met important criteria - currently grown by farmers, have a high yield potential, be disease and pest-resistant, grow to the right size and have strong enough roots to withstand monsoon-force winds - to find out which ones could were optimal in regards to nitrogen.
Nitrogen is one of three main nutrients required for crops to grow, it also costs the most to produce.
They concentrated only on Japonica (the rice used in sushi) and Indica, the world's most popular rice type commonly grown in China, India and Southeast Asia and identified 19 "superstar" varieties of rice that can reduce fertilizer loss and cut down on environmental pollution in the process.
Nitrogen, when applied as fertilizer, is taken up inefficiently by most crops. In tropical rice fields, as much as 50 to 70 percent can be lost. The problem is that nitrogen negatively impacts water quality by contaminating nearby watersheds or leaching into ground water. It's also a significant source of gases such as ammonia and nitrogen oxide, which are not only harmful to aquatic life but also a significant source of greenhouse gas emissions.
The study identified a novel class of chemicals produced and released by the roots of rice crops that directly influence the metabolism of soil microbes. They found that key microbial reactions that lead to an inefficiency in nitrogen capture can be significantly reduced in certain varieties of rice plants through the action of those specific chemicals released from root cells.
One of the main reasons crops waste so much fertilizer is that they were bred that way. In the past fertilizers were relatively inexpensive to produce because fossil fuels were abundant and cheap. As a result, plant geneticists bred crops that responded to high fertilizer use regardless of how efficient they were at using nitrogen.
Optimizing food crops scientifically will make them both cost-effective and better for the environment. Spurred on by Greenpeace and other anti-science groups, the Philippines has been scared about agriculture science, but studies like this may show that cost and impact aren't incompatible.