Just like many of the flowers in your garden, rice has traditionally been an annual plant – that means new crops have to be sown every year. A perennial version is now available, however, which comes back on its own over multiple growing seasons.
The perennial rice has been in development since 1999, and is the result of a collaboration between the University of Illinois, Yunnan University, the University of Queensland, and The Land Institute in Kansas. It's a hybrid, created by crossing an Asian domesticated annual rice (Oryza sativa) with a related African wild perennial rice (Oryza longistaminata).
After large-scale field trials in 2016, one variety of the rice was commercially released in China in 2018. It has since been studied at three locations in China's Yunnan province, where it was farmed alongside traditional annual rice crops.
First and foremost, it was observed that the perennial rice has to be planted just once, after which it can be harvested up to eight times without any reduction in yield. As a result, farmers not only save money on seeds and fertilizer, but they also don't have to go to the considerable time and effort of planting new crops every season.
It should be noted that annual rice will regrow if cut back after the initial harvest, although the subsequent second harvest will be much lower-yielding.
Speaking of which, the scientists additionally noted that over the first four years, the yield of the perennial rice was essentially the same as that of the annual rice crops – 6.8 megagrams per hectare vs. 6.7 megagrams per hectare, respectively. Its yields did begin to drop going into the fifth year, so re-sowing is now being recommended once every four years (with two harvests per year).
It was also found that farmers growing the perennial rice put in about 60% less labor – since they didn't have to sow new crops every year – plus they only spent about half as much on expenses such as seeds and fertilizer. This translated into profits ranging from 17% to 161%, depending on the specific locations.
As an added benefit, because the soil in the perennial rice paddies didn't need to be tilled for resowing every year, it was found to have higher organic carbon and nitrogen levels than soil in the annual rice paddies.
The Land Institute's chief scientist Timothy Crews, co-author of the study, told us that while the perennial seeds might initially be slightly more expensive than annual seeds, that difference will soon be negated by the fact that more annual seeds have to be purchased every year.
Three varieties of the perennial rice have now been released in China, along with one in Uganda, where they're being grown by a combined total of 55,752 smallhold farmers. The researchers are currently working on boosting traits such as disease resistance and drought tolerance, making the rice suitable for a wider range of environments.
"I think now, with perennial rice in farmers’ fields, we have turned a corner," said U Illinois' Prof. Erik Sacks, another co-author. "We have been feeding humanity by growing these grains as annuals since the dawn of agriculture, but it wasn’t necessarily the better way. Now we can consciously choose to make a better crop, and a better, more sustainable agriculture."
The paper, which was additionally co-authored by Fengyi Hu and Dayun Tao, was recently published in the journal Nature Sustainability.
Source: University of Illinois
