Rising temperatures are reshaping crop suitability in Japan, with projections indicating that traditional mikan cultivation areas may become increasingly unsuitable, while avocado production zones expand.

Ehime Prefecture, one of Japan’s largest mikan producers, has begun promoting avocado cultivation with local authorities distributing seedlings to farmers. This initiative, initially aimed at using idle farmland, has gained attention as high summer temperatures in recent years have caused sunburn and other quality issues in mikan. Shizuoka Prefecture has also announced plans to become the country’s leading avocado production center within 10 years, allocating 18 million yen (about US$118,000) for research and development.

Officials in Shizuoka emphasize the prefecture’s proximity to major consumption areas, enabling delivery of domestically grown avocados in a fully ripened state. Avocados, grown outdoors, begin bearing fruit within several years of planting, a shorter period compared to mikan. Authorities stress the need to identify winter-hardy avocado varieties and establish reliable cultivation and quality management systems.

Climate forecasts and crop suitability
The National Agriculture and Food Research Organization (NARO) published forecast maps in March showing how climate change will alter cultivation areas for mikan and avocados. Mikan requires a narrow annual mean temperature range of 15 to 18 degrees Celsius. Even a one-degree rise increases risks of sunburn and peeling, leading to lower yields.

Under NARO’s models, suitable areas for mikan shift northward by mid-century, expanding inland along the Pacific coast and extending up the Sea of Japan coast to the Hokuriku region. Toward the end of the century, major production areas in Kagoshima, Ehime, Wakayama, and Shizuoka may no longer be viable under “intermediate” and “very high” greenhouse gas emission scenarios. New regions in Niigata and Toyama are projected to become suitable for mikan cultivation.

Avocado cultivation areas are forecast to expand 2.5 to 3.7 times by mid-century and up to 7.7 times by the end of the century. In the highest emissions scenario, about 95,000 square kilometers of Japan would fall within a suitable temperature zone for avocado production, including the Kanto plains and the Izu and Boso peninsulas.

Outlook
Avocados currently face limitations, including a restricted range of approved agrochemicals and uncertainty over the best varieties for Japan’s climate. They are also vulnerable to typhoons. However, NARO notes that stable domestic production at consistent quality could enable Japanese-grown avocados to compete with imports in the long term.

Source: The Asahi Shimbun