Abstract: A frost prone farmland in Shangqiu was chosen as the study area where a winter wheat cultivar Aikang 58 was planted. After natural frosts occurred in April 7，10 and 21， 2013， yield components of 100 sampling points （the interval between samples is 5m） were measured at wheat maturity. Frost injury was divided into five grades according to the proportion of the damaged part of each ear. Damaged ear index （DEI） was established as an index for evaluating the overall frost injury. Differences among the frosted grades for grain yield and its components per 100 ears were compared. To reveal the change rules of yield components with the increasing frost injuries， the trends of grain yield and its components of the different grades per 100 ears and total ear number and actual yield in 1 square meters were fitted by mathematical functions. The results showed that ear number， kernel number per ear and actual grain weight of the frosted ears were significantly lower than that of nonfrozen ears （P＜0.01）. With the higher grades， kernel number per ear and actual grain weight were lower， and ear numbers showed a trend to increase slightly after decrease obviously， and 1000kernel weight increased significantly and then decreased （P＜0.01）. In each 100 ears， ear number， kernel number per ear， 1000kernel weight and actual grain weight formed the decreasing trends with concave upward parabolic shape， linear function shape， concave downward parabolic shape and power function shape， respectively. With the higher DEI， total ear number and actual yield in 1 square meters was lower and formed the decreasing trends with power function shape and linear function shape， respectively. The results were helpful to reveal the influence mechanism of late frost injury at the jointing stage to booting stage of winter wheat．

Key words: Winter wheat, Yield components, Frost injury grade, Damaged ear index, Trend fitting