The Quest to Save the ‘King’ of Japanese Rice From Rising Temperatures

River Akira Davis and Hisako Ueno

Scientists in Japan are racing against time to save the country’s most popular rice from the devastating effects of climate change. At a research center in Niigata prefecture, Japan’s mountainous heartland of rice production, a team of scientists has identified a pattern within rice DNA that makes certain varieties of the plant resistant to heat.

They are now embarking on a quest to crossbreed that genetic signature into Koshihikari, the Japanese rice that has overwhelmingly topped supermarket sales in the country for over 40 years. Whether they succeed could determine the fate of the bouncy and sweet cultivar long regarded as the “king” of Japanese rices. Last year, Koshihikari rice across Japan was devastated by the hottest summer on record. Compared with other types of rice, Koshihikari has a particularly low tolerance for heat, and the scorching temperatures turned its grains cloudy and brittle.

That was a crushing blow to farmers in Niigata, where Koshihikari rice is the economy’s biggest agricultural output. Last year, less than 5% of the prefecture’s rice was given the top quality grade that allows it to be sold for a higher price — about $6 or $7 more for each 130-pound bag. Over the past decade, typically about 80% or more of Koshihikari rice from Niigata has been ranked top-tier.

Koshihikari is one small part of a global agriculture industry that is being upended by rising temperatures. From grape growers in France’s Bordeaux region to cocoa harvesters in Africa, farmers have been forced to alter practices that have been in place for generations.

Heat is also affecting rice production in other Asian growing hubs such as Vietnam and Thailand. “The story is ultimately much bigger than Japan,” said Charles Hart, a senior commodities analyst at BMI, a unit of the research firm Fitch Solutions.

“Rice is very water-intensive, and in a context of gradually increasing temperatures and more frequent periods of intense heat, heat-resistant rice needs to be the direction of travel,” Hart said. In Japan, where the government uses tariffs to limit rice imports, last year’s poor harvest of Koshihikari contributed to widespread shortages of rice this year. Empty supermarket shelves set off panic and led to calls on Japanese officials to release the country’s strategic rice reserves.

“For us, last summer was an extreme shock,” said Kazuyuki Kobayashi, a technical specialist at the Niigata Agricultural Research Institute, which was established in 1895. It has left scientists at the research center racing to develop new Koshihikari capable of withstanding such spells of extreme heat.

“We had been developing rice based on projections of how high temperatures would get around the end of the 21st century,” Kobayashi said. In Niigata last summer, “those temperatures had already arrived,” he said.

On an overcast day in September, Shingo Kuwabara, 38, was midway through harvesting Koshihikari when a downpour forced him to take a break indoors. Kuwabara watches over nearly 100 acres that have been in his family for more than 300 years.

Kuwabara’s farm is in the Uonuma region of southern Niigata — an area known for producing some of Japan’s best Koshihikari. Mineral-rich snowmelt from the surrounding mountains keeps the rice paddies moist. Frequent breezes and evening showers keep temperatures cool.

Last summer, Kuwabara’s farm and surrounding areas were slammed with temperatures in the high 80s — around 10 degrees hotter than the ideal rice-growing temperature. Kuwabara said less than 40% of his Koshihikari was given the top-tier grade. “Other farmers and I often spoke about how there could be a limit to growing Koshihikari in the future,” Kuwabara said. Then last year, “we saw many of our Koshihikari grains turn white,” he said.

Around a decade ago, Kuwabara began growing a small amount of Shinnosuke — a rice bred by the Niigata Agricultural Research Institute that is capable of withstanding extreme temperatures. During last year’s heat wave, Kuwabara’s Shinnosuke crops stayed healthy.

Shinnosuke accounts for only 5% of Kuwabara’s rice. But if temperatures keep rising as they have, by the time he passes the farm on to the next generation, it may need to account for about half of the farm’s output, he said.

Shinnosuke has a few downsides. It tends to become infected with fungus, and rice retailers in Niigata say consumers still prefer the taste of the smaller-grain Koshihikari.

Many farmers in Niigata say they are reluctant to move away from Koshihikari. It has long been the pride of Niigata, providing families with stable income for generations.

The incentive to change is especially low for a majority of Japanese farmers who are retirement age or older and have no heir lined up to take over their land.

“It’s a gamble, whether to increase Shinnosuke or not,” Kuwabara said. For now, “I’m holding out hope that Koshihikari will be developed as a heat-resistant crop,” he said.

Agricultural researchers in Japan say the key to cultivating a new type of heat-resistant Koshihikari may reside within the DNA of other rices, including Shinnosuke’s.

At the Niigata Agricultural Research Institute, scientists have identified a DNA sequence that they say could give Koshihikari the ability to withstand extreme heat. The process of introducing the special DNA sequence into the rice is laborious.

Scientists at the research center say it takes around 10 to 15 years to breed a new type of rice from start to finish. With the speed at which temperatures have shifted in recent years in the back of their minds, the team is straining to finish the process within the next 10 years.

On sprawling farm grounds behind the institute’s main buildings, researchers are growing hybrid crossbreeds of Koshihikari and other heat-resistant rices. Those hybrid rices will then be crossbred again with Koshihikari. And that process will be repeated until they get rice that is like Koshihikari in all ways, but can also withstand heat.

Any new variety “must be as delicious as Koshihikari has always been,” Kobayashi said. “Otherwise, farmers will not want to grow it.”