Transforming Agriculture, Perennially

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Small farms in China are warming to new perennial rice crop

Publication: South China Morning Post

Author: Echo Xie

When Liang Yuxin first heard about a new rice variety that could be harvested for years without replanting, he was eager to try it out.

If his experiment are successful, it would give confidence to local farmers, said Liang, the representative of a farmers’ cooperative in China’s southwestern region of Guangxi.

“Many plots are lying fallow in the rural areas of southern China, and the planting cost is high. But if I can plant rice once and reap harvests for several years, the cost will be greatly reduced,” Liang said. “Why won’t I try it?”

Liang is one of more than 40,000 small farmers in China who have chosen to plant this new kind of rice.

Developed by researchers from Yunnan University over two decades, the perennial rice variety has not only demonstrated yield potential but also lowered costs and enhanced soil quality, according to a study published recently in the peer-reviewed journal Nature Sustainability.

The researchers crossed an Asian domesticated annual rice cultivar with a wild perennial African variety to create a new hybrid, which they called Perennial Rice 23 (PR23).

Its yield has been shown to be slightly higher than that for annual rice for the first four years, at an average of 6.8 tonnes per hectare (2.5 acres) per season, compared to 6.7 tonnes of the replanted variety.

While the costs are similar for both kinds of rice in the first season, the perennial rice variety does not need seeding, planting, and plowing for several years, which means farmers can save up to US$1,400 per subsequent season.

Overall, perennial rice can cut labor costs by 60 percent and halve input costs for each regrowth cycle. The net economic benefits can range from 17 percent to as much as 161 percent above annual rice in different planting locations, according to the authors of the study.

PR23 was made commercially available for Chinese farmers in 2018 and was among the 29 varieties recommended to them by the Ministry of Agriculture and Rural Affairs earlier this year.

Last year, the total planted area of perennial rice in China was over 15,000 hectares, four times higher than in 2020.

Liang planted another perennial variety, the PR25, across more than 1 hectare in August and harvested over 8 tonnes three months later.

“We have confidence in perennial rice,” said Liang, who aims to further expand his area of cultivation.

“Normally, it is very hard to earn money by growing rice. But after planting perennial rice, I am pleased that [we can] make some money if we manage it well. It will be a great boon to farmers if its cultivation is promoted.”

Erik Sacks, professor in the crop sciences department at the University of Illinois Urbana-Champaign and co-author of the study, said less frequent plowing in the perennial rice system conserved soil and built organic matter content.

“Soils with high organic matter are more productive than soils with low organic matter because the organic matter can loosely hold onto plant nutrients and make them available for crop growth,” he explained.

Growing perennial rice also saved water, as less water was needed to obtain “ratoon crops” – or second harvests – of rice, compared with getting a new crop from seeds or transplanted seedlings, Sacks added.

Lead author Zhang Shilai, a professor at Yunnan University’s School of Agriculture, said the team would continue to work on developing cold-tolerant, heat-tolerant, and disease-resistant varieties so that they can be promoted over larger regions.

“We promoted perennial rice across Yunnan and addressed the key issues that matter most to farmers: yields, costs, taste, and stable production across multiple seasons. Many of these farmers grow rice as a staple food for their families, so perennial rice must compete against other rice varieties,” Zhang said.

In April, Yunnan University and genomics organization BGI Group set up a perennial rice joint venture focusing on large-scale localization.

However, the study also noted challenges with pests, diseases, and weeds, which might be easier to control in annual crops.

“But perennial rice is still a very new crop, and we predict that cropping systems and pest-resistant varieties will be developed,” said Tim Crews, study co-author and chief scientist at The Land Institute, a Kansas-based non-profit organization.

The new perennial varieties hold special significance for China. The world’s most populous country is also its top consumer of rice, accounting for about 30 per cent of total global demand.

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