Correlation Analysis between Pollen Fertility and Panicle Exsertion in P(T) GMS Rice with eui Gene

Panicle enclosure is a typical phenotype of almost all male-sterile lines,which greatly reduces seed production of hybrid rice due to its blocking of normal pollination.Therefore,large amount of exogenous GA has to be used for inducing panicle exsertion.However,GA application not only increases the cost of seed production but also greatly increases the rate of seed germination on the panicle,resulting in decreased quality and shortened storage life of hybrid seeds.Elongated uppermost internode(eui) gene can promote elongation of the uppermost internode,which is a very useful genetical factor for eliminating panicle enclosure.However,the panicle enclosure in P(T)GMS(photo or thermo-sensitive genic male sterile) rice with eui gene shows substantial variation at different heading stages.In this paper,P(T)GMS rice was used to analyze the relationship between pollen fertility and panicle exsertion.The results were as follows: (1) Under condition of natural long day-length and high temperature,P(T)GMS rice with eui gene was male-sterile and the panicle exsertion increased with increasing of total sterile pollens in per anther.Sheathed panicle was exserted when the number of total sterile pollens in per anther was more than 700.Regarding to length of each internode,the length of first internode increased as the same with the length of panicle exsertion.Little variation was recorded in length of other internodes and flag leaf sheath.Therefore,panicle exsertion is due to the elongation of first internode.(2) The pollen became stainable and panicle exsertion increased under condition of natural short day-length and low temperature.When the ratio of stained pollen was 0.01%10.00%,significant correlation was found between stained pollen and panicle exsertion.As the ratio of stained pollen was higher then 10.00%,the correlation was decreased gradually.The length of first internode had the similar correlation with the ratio of stained pollen.(3) Similar correlation between pollen fertility and length of first internode in P(T)GMS rice with eui gene and Pei'ai 64S(PTGMS rice without eui gene) were recorded under temperature from 28℃ to 20℃.The panicle exsertion in P(T)GMS rice with eui gene at 20℃ was 24.7 cm longer than that at 28℃,while that in Pei'ai 64S only 12.3 cm.The length of first internode in P(T)GMS rice with eui gene showed more variation than in Pei'ai 64S.