Abstract: Based on the climate data of meteorological stations from 1973 to 2017 in Zhejiang Province and the heat stress index of tea plant, temporal variability of heat hurting grade of tea plant was analyzed with line trend rate and Mann-kendall method. Based on Mann-kendall method, the heat injure of tea plant in Zhejiang Province was divided into three periods: 1973—1983, 1988—2002 and 2003—2017. The probabilities of heat stress to tea plant in each period were calculated with information diffusion theory. The result of t-test showed that the probability of heat hurt to tea plant in 2003—2017 was larger than in the periods of 1973—1987 and 1988—2002. Risk value of heat injure of tea plant was calculated by using probabilities of each heat hurting grade of tea plant in 2003—2017. Based on risk values, Zhejiang province could be divided into five regions: low risk, relatively low risk, moderate risk, relatively high risk and high risk areas. Among these areas, the risk values of 18 coastal counties as well as Qingyuan, Taishun and Kaihua were low. The risk values of 5 mountain counties, such as Suichang and 9 counties near the sea or Taihu were relatively low. The risk values of 13 counties in the middle of Zhejiang Province and on a plain or in the middle of the basin such as Lishui were high. The high risk area included 14 counties such as Shengzhou. The moderate risk area contained 10 counties. It could reflect the risk of heat injure of tea plant in Zhejiang Province at present and in a certain period in the future. The results provided a basis for the defense of heat stress to tea plant in Zhejiang.

Key words: Mann-kendall method, information diffusion theory, t-test, tea plant, heat injure risk regionalization