Abstract: Influences of high temperature stress on anther physiology characteristic,pollen vitality and seed setting of conventional japonica rice variety Nanjing 43 and indica hybrid rice variety Changyou 2 during heading stage were studied.The results showed that the content of proline(Pro),aminophenol,soluble protein,ascorbic acid(ASA) and glutathione(GSH) of anther was reduced significantly by high temperature stress(p<0.01),compared with blank control.With the elevation of stress temperature and extension of stress time,the pollen vitality,pollen germination ratio,seed setting ratio,number of filled grains per panicle and yield per plant of two varieties suffered a sharply decline,but thousand seed weights had little change.Therefore,it was concluded that the high temperature stress destroyed cell membrane structure and function of anther,affected the pollen vitality and the pollen germination ratio,reduced the seed setting rate and the number of filled grains per panicle.These finally led to reduction of the rice yield.By contrast with two varieties,the damage of high temperature stress on the pollen vitality,pollen germination ratio and seed setting ratio for variety Changyou 2 was lower than that for variety Nanjing 43.This indicated that the ability of high temperature tolerance for variety Changyou 2 was stronger than that for variety Nanjing 43.According to the correlation analysis,the rate of seed setting of two varieties showed a significantly linear correlation with the rate of pollen vitality and pollen germination ratio(p<0.01),respectively.Therefore,it was possible that one of reasons affecting low seed setting ratio might be the reduction of the pollen vitality and the pollen germination ratio.

Key words: Heading stage, Heading stage, High temperature stress, Rice, Blooming, Seed setting ratio