Field survey on rice spikelet sterility in an extremely hot summer of 2018 in Japan

In rice (Oryza sativa L.), heat-induced spikelet sterility (HISS) has long been recognized a major threat in the production, and currently potential risk of yield reduction is likely to be increasing under global warming. However, there have few studies on HISS conducted field conditions. recent years Japan, extremely high temperatures frequently recorded daytime during summer. 2018, heat wave lasted from mid-July late August, which overlapped typical heading period eastern western Honshu raised concern about flowering. To examine this possibility, we surveyed eight prefectures Kanto, Tokai, Kinki regions. During surveys 2018 2019, collected data ‘Koshihikari’, most popular variety ranged 3.7 15.4% paddy fields. The tended higher fields where occurred wave. We modeled rate using dose based mean panicle temperature, with threshold for at 33°C. model estimates meteorological showed that can induced even current climatic conditions, depending timing heading. Considering projected warming, study raises an issue plants would face temperate climate Japan.