Abstract: Diurnal growth rates of stem elongation and leaf area of 7 1-year-old paulownia clones, were observed at early growth stage (June 15th-18th),middle growth stage (August 2nd-4th) and late growth stage(August 28th-31th,1991) respectively in the nursery of Yenzhou county,Shandong province.The results show that the major meteorological factors affecting the stemelongation growth rate were arranged the following sequence: relative humi-dity and temperature in early and middle stage, temperature and illuminationin late stage, affecting the growth rate of leaf area were relation humidity,temperature and illumination in early stage, temperature and illumination inboth middle and late stage. The peak values of both stem elongation and leafarea growth rate are double-peak curves. Their peak values appear at 18:00-24:00 and 12:00-18:00 respectiveiy. Each of the 7 clones has a differentdiural and seasonal growth rhythm, based on which, they may be classifiedinto several different growth types. The results of ths research provide method and basis for the comparative study on the ecological and physiological characterisics of Paulownia genus.

Key words: Paulownia, Clones, Growth rhythm