Abstract: The effects of high temperature stress on yield components and grain quality of japonica rice Yangdao 6 and japonica rice Nanjing 43 in plant growth chamber with two temperature treatments during heading stage were studied.The results showed that brown rice rate,milled rice rate,head rice rate,number of grains per panicles,seed setting rate,kernel weight,soluble sugar content and protein content in two rice varieties were lower,chalkiness rate and chalkiness degree were higher.Moreover,the damage on yield components and grain quality in two rice varieties were more serious with elevation of stress temperature and elongation of stress time.Index of heat sensitivity(HIS) and the damage degree for Nanjing 43 was higher than that for Yangdao 6 under the same high temperature stress.So the capacity of high temperature tolerance of Yangdao 6 was higher than Nanjing 43.The results could provide important theoretical evidence for revealing the damage mechanism on yield components and grain quality,selecting stronger heat tolerance of rice cultivar.

Key words: Rice, Rice, Heading stage, High temperature stress, Yield components, Grain quality