Japan’s farmers are increasingly turning to heat-resistant varieties of rice as prolonged periods of extreme heat and dry weather threaten the country’s staple food crop and raise concerns over future harvests, food prices and agricultural sustainability.
In the rural town of Shiroishi in southwestern Japan, farmer Haruki Kawasaki is preparing to harvest hinatamaru, a rice variety that has performed well despite another hot and dry summer. The variety is among a growing number of heat-tolerant strains being adopted by farmers seeking to adapt to changing weather conditions.
For Kawasaki, 63, rising temperatures have also changed the way farming is carried out. Instead of spending an entire day working in the fields, he and his team now begin early in the morning and stop around midday because afternoon temperatures have become too high. Even the mornings, he says, are no longer particularly cool.
Japan has experienced increasingly severe heat in recent years, with farmers facing record temperatures and inadequate rainfall during the past three summers. The country’s meteorological authorities have introduced a new classification for days when temperatures exceed 40C, reflecting the severity of the heat being experienced in parts of the country.
High temperatures can severely affect rice after the plants flower. Instead of developing into healthy, translucent grains, rice exposed to prolonged heat can become immature and chalky. Such grains are more likely to crack during polishing and may fail to meet the quality requirements for top-grade rice, affecting both farmers’ incomes and the supply of marketable grain.
The changing climate has prompted farmers in several regions to reconsider traditional rice varieties. Saga prefecture, in southwestern Japan, has emerged as a major centre for the adoption of heat-tolerant strains. Agriculture ministry figures show that such varieties account for nearly 67% of rice-growing acreage in Saga. Nagasaki has adopted them across just under half of its rice acreage, while Shimane has reached about 47%.
The shift follows years of research and experimentation. Hinnatamaru, which is now gaining popularity in Saga, was developed after about 12 years of research involving cross-breeding, controlled cultivation and field testing. Successful trials in 2024 accelerated its adoption.
Japan’s experience with heat-related crop damage has also demonstrated the wider consequences of extreme weather. Record heat in 2023 was cited as one factor behind the “Reiwa rice crisis” the following year, when the government released emergency rice stockpiles amid shortages and rising prices.
The spread of heat-resistant varieties is now being seen across most of Japan. According to agriculture ministry data, such rice was cultivated across 248,000 hectares last year, equivalent to about 18% of the country’s total rice-growing area. This represented a sharp increase from 42,000 hectares the previous year.
The adaptation is not limited to rice. Farmers in some areas are changing their working hours to avoid peak temperatures, while some fruit and vegetable growers are inspecting crops at night. Others are experimenting with crops better suited to warmer conditions, including avocados, bitter melon and okra.
However, farmers and environmental groups have warned that technological and agricultural adaptation alone may not be enough if extreme weather continues to intensify. Greenpeace Japan has said prolonged heat is threatening several important autumn crops, including rice and sweet potatoes, while warning of potential consequences for food prices and national food security.
Japan’s ageing agricultural workforce adds another challenge. Nearly 70% of the country’s agricultural workers are aged 65 or older, making it increasingly important for farmers to find varieties and farming methods that can withstand harsher conditions without adding to the physical burden of agricultural work.
For farmers such as Kawasaki, the priority is to ensure that new varieties can survive the heat without sacrificing the taste associated with Japanese rice. His experience with hinatamaru suggests that adaptation is possible, but the rapid spread of heat-tolerant varieties also reflects the growing pressure on Japanese agriculture to respond to a warmer and more unpredictable climate.
