Abstract: Diurnal variation of transpiration rate (Tr)and stomatal resistance (Rs)of Taxus media cv.Hicksii and some ecological factors were determined by using LI-1600 stable porometer and the relationship between transpiration rate(Tr)and influencing factors was discussed by the methods of multiple regression analysis and grey relation grades analysis, The results indicated that the major influencing factors were air temperature(Ta)and leaf temperature(Tl), the next were photon flux density(PFD), air relative humidity(Rh)and stomatal resistance (Rs).The conclusions of multiple regression analysis and grey relation grades analysis were unanimous.According to the analysis of the relationship between Tr and Rs, there was non-linear relationship.The equation was following:Tr=12.789-13.419 lg Rs(R²=0.971 7).

Key words: transpiration rate, ecological factor, stomatal resistance, multiple regression analysis, grey relation grades analysis