Grains that grow year after year without having to replant could save money and help the environment. The biggest real-world test of such a crop is showing promise. Researchers have found that perennial rice can yield harvests as plentiful as the conventional, annually planted crop while benefiting the soil and saving small farmers a lot of money.
A soil and crop scientist at the International Maize and Wheat Improvement Center was not involved with the work.
The crop's results show it is a potential game-changer, according to an anthropologist at the Australian Centre for International Agricultural Research. He and others say that the advance could help China grow more food.
Susan McCouch, a rice geneticist at Cornell University, says it's difficult to say whether the perennial rice will catch on.
Rice is perennial. Rice roots are different from wheat or corn. Farmers plow up paddies and plant new seeds because the second growth doesn't yield as much as the first. The perennial rice doesn't grow back as quickly as the improved one. Researchers crossed an Asian variety of rice with a Nigerian variety. A variety of rice called Perennial Rice 23 became commercially available to Chinese farmers. A crop scientist at the Africa Rice Center says this was a breakthrough.
The magnitude of any economic and environmental benefits was not known. A geneticist at the University organized long experiments. They arranged with farmers in three places to plant the rice and harvest it twice a year for five years.
PR23 averaged over 6 tons of rice perhectare, slightly higher than the annual rice. The crop grew again and again without sacrificing the size of the harvest. The yields of PR23 declined for some reason in the fifth year.
Perennial rice improved the soil. The crop left more carbon and nitrogen in the soil than annual rice. Retaining water is beneficial for rice grown in regions that get a lot of rain. By next year, the researchers hope to have results from a 6-year trial of how much greenhouse gas perennial rice emits. paddy-grown rice is a major global source of methane.
The new rice may be good for farmers. The effort involved in growing PR23 was compared with the effort involved in growing the annual varieties. Fuel for plowing, the seedlings, and other costs were the same for the first year. Perennial rice costs less each year. Between 78 and 78 fewer days of labor were taken by eachhectare.
Farmers are drawn to those advantages. The total area planted in 2020 was doubled to 15,333 hectares thanks to the seed and training provided by the university. China has 27 million hectares of rice paddies. Perennial rice has been promoted by the government. PR23 is one of 29 varieties recommended to farmers by China.
The largest beneficiary of the labor savings will likely be women and children, who do most of the planting of rice in developing countries. He says that mothers will have more time to look after the family and get the children to school. Farmers can either grow more rice or make more money by working in side jobs.
Grnbhel cautions that more study needs to be done to see how popular PR23 is and how labor savings will affect farmers.
Potential risks are noted by researchers. Farmers can till less if PR23 is used. When insects feed on the regenerating sprout in the spring, they can transmit diseases. The researchers found that fields with PR23 needed more than regular rice to be weed free. The perennial rice needs to be killed because of its larger and deeper roots if it is to continue to grow.
There will soon be more focus on the potential benefits. Perennial rice is being tried in 17 countries. In Asia, plowing for rise causes soil erosion in small rice fields.
There is a proof of concept by the creators of PR23 I hope that there's some strength in numbers.
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