Researchers from the Agriculture and Food Research Organization conducted a study that found climate change may allow rice farmers to farm rice for longer as the climate warms.

Rice is an annual plant, which means it goes through its life cycle in one harvest season. But in tropical areas, and with proper care, rice can continue to grow year after year. To encourage continuous growth, farmers use a method called ratooning. When ratooning, farmers cut rice above the ground and let it regrow. Ratooning requires a longer growing season. While this isn’t a problem in tropical climates, it becomes an issue with cooler climates, like in Japan.

The average temperatures in Japan have been rising in recent years due to climate change. Higher temperatures mean there is more time for rice to grow. Rice seedlings will be able to be transplanted earlier in spring and harvest later into the year.

Comparison of the two cut heights of rice five days after harvesting the first crop. Source: Chiemi Nagamatsu

The goal of this study was to determine the effects that harvest time and cutting height of the first harvest have on the yield of the first and second rice harvest. They ultimately wanted to find new farming strategies so farmers can increase their rice yield and adjust to climate change.

During the study, the team compared two harvest times and two cutting heights. After the first harvest, they collected seeds from the cut-off portion of rice plants. The yield of both harvests was measured by counting and weighing seeds.

The team found that total grain yield and individual yields of the first and second harvest crops were different depending on the harvest times and cutting heights. Researchers weren’t surprised, they already knew that harvest time and cutting heights had an effect on yield. Rice plants harvested at the normal time for the first crop yielded more seed than rice plants harvested earlier in the season. At both harvest times, rice harvested at high cutting height produced a higher yield because plants cut at a higher height have more access to energy and nutrients stored in leaves and stems. By combining normal harvest time with high cutting height, rice yield is increased when rice ratooning in Japan.

The study was published in the Agronomy Journal.