[P4] Crop Genetics and Physiology

[P4-31] Heat Stress Impact on Heading and Ripening in Major Korean Rice Variety

^○Woonha Hwang¹, Chungkeun Lee², Jaehyeok Jung³, Hyeonseock Lee⁴, Seoyeong Yang⁵, Yeonhwa Lim⁶, Myeonggu Choi⁷ (1.Crop Production and Physiology Division, National Institute of Crop Science, Korea, 2.Crop Production and Physiology Division, National Institute of Crop Science, Korea, 3.Crop Production and Physiology Division, National Institute of Crop Science, Korea, 4.Crop Production and Physiology Division, National Institute of Crop Science, Korea, 5.Crop Production and Physiology Division, National Institute of Crop Science, Korea, 6.Crop Production and Physiology Division, National Institute of Crop Science, Korea, 7.Crop Production and Physiology Division, National Institute of Crop Science, Korea)

Heat stress is one of big stress in rice cultivation. Even mean temperature is gradually increasing and extremly high tempertaure even is also increasing in Korea. In these condition, the understanding of heat stress impact on rice is important to harvest stable yield and quality. Therefore, we checked heat stress impact on rice flowering, heading and ripening stage using major Korean varieties. To check flowering characters of rice, we used 11 Korean varieties. After cultivation under natural condition until heading, the pots were transported in green house which temperature was controlled. Until 30 degree of mean temperature, the flowering time did not changed. However, in 33 degree of mean temperature, flowering time changed earlier then other temperature condition. Fertility also changed under 33 degree, significant reduced. Under 33 degree, anthor viobility and germination rate were significantly reduced. In high temperature condition, heading time also changed. The growth days from transplanting to heading reuced about 3.5 days under 1 degree of mean temperature changed. In ripening stage, heat stress impact on 1000 brown rice wieght, rice quality and protein content. 1000 brown rice weight was reduced about 0.02 g according to 1 degree of mean temperature. The bigger rice showed more reduction in heat stress. And head rice rate was reduced about 5% and immature rice rate was increased about 1.9% by 1 degree of mean temperature.