Drying temperature regulates vigor of high moisture rice seeds via involvement in phytohormone,ROS,and relevant gene expression

BACKGROUND Rice is an important food crop in China. Seed drying is an important step in the production of rice seeds. However, the regulatory mechanism of the effect of drying temperature on vigor of rice seeds with high initial moisture content (IMC) has not been examined. RESULTS This study presents hot-air drying of rice seeds with high IMC (>30%) to assess the effect of drying temperature (35, 41, and 47 degrees C) on drying performance and seed vigor in terms of germination capacity. The results show a significant positive correlation between the drying rate, seed temperature, and drying temperature. High-temperature drying tends to cause a large accumulation of reactive oxygen species (ROS) and increases the activity of antioxidant enzymes in rice seeds. High-temperature drying also significantly increased abscisic acid (ABA) content and decreased gibberellin (GA) content through the regulation of the activity of metabolism related-enzymes. Moreover, changes in GA and ABA metabolism during early seed germination might be an important reason for the decrease in seed vigor with high-temperature drying. High-temperature drying also significantly inhibited the activity of alpha-amylase during early seed germination. CONCLUSION A drying temperature of 35 degrees C was safe for rice seeds with high IMC, whereas higher drying temperatures (41 and 47 degrees C) reduced rice seed vigor remarkably. The metabolism of ROS, antioxidant enzymes, GA, ABA, and alpha-amylase might be closely involved in the regulation of the effect of drying temperature on the seed vigor of rice seeds with high IMC. The results of this study, therefore, provide a theoretical basis and technical guidance for mechanical drying of rice seeds. (c) 2020 Society of Chemical Industry

Automated summary

High-temperature drying of rice seeds with high initial moisture content leads to accumulation of reactive oxygen species and increased activity of antioxidant enzymes. It also significantly affects the content of abscisic acid and gibberellin, leading to decreased seed vigor during germination. Additionally, high-temperature drying inhibits the activity of alpha-amylase during early seed germination.