Pre-harvest sprouting susceptibility of Baromi2, a floury rice variety, and its impact on seed viability

Pre-harvest sprouting (PHS) is a critical issue in rice production, particularly under extreme weather conditions during the ripening stage. This study investigated the PHS characteristics of Baromi2, a powdery rice variety, in comparison with Chamdongjin (CDJ), with a focus on the effects of rainfall duration and drying temperature on seed viability. The results showed that PHS increased significantly with the number of days after heading progressed, particularly at higher temperatures (25–30 °C). Sprouting initially occurred in the upper spikelets and gradually spread downward as ripening progressed. Continuous rainfall during the late ripening stage further exacerbated PHS, with Baromi2 exhibiting a higher sprouting percentage than CDJ. The sprouting percentage of Baromi2 was notably higher under extended rainfall exposure and increased with drying temperature, reaching nearly complete sprouting (99%) after five days of rainfall followed by drying at 30 °C. Additionally, seed vigor declined as rainfall exposure and drying temperature increased, with the germination percentage of Baromi2 falling below 50% when subjected to four or more days of rainfall followed by drying at 25–30 °C. These findings underscore the importance of developing PHS-resistant varieties and implementing effective post-harvest strategies.