The Annual Growth Parameters and Their Variation of Paulownia Seedlings

Based on testing 16 Paulownia clones in seedling stage, the growth pattern and growth parameters in seedling stage were studied. The results indicated that the growth of Paulownia seedlings can be modeled by sigmoid curve, and can be divided into 3 stages: first slow growth stage, fast growth stage and second slow growth stage. The main parameters are the beginning date of fast growth(DB), the middle date of fast growth(DM), the ending date of fast growth(DE), the length of fast growth(LG), the growth rate(RG) and increment at each date, the average growth rate(ARG), the maximum rate of growth(XRG), and the maximum value of diameter(KD) and height(KH) of annual growth of Paulownia seedlings. The annual growth parameters of diameter of 185 seedlings of 16 clones are as follows: DB June 12, RG 0.033 cm· d-1 , diameter 1.08 cm; DM July 16, XRG 0.049 cm·d-1 , diameter 2.57 cm; DE August 20, diameter 4.06 cm; LG 69 days, total annual growth 5.13 cm. The annual growth parameters of seedling height are: DB July 8, RG 0.049 m·d-1 , height 0.88 m; DM July 27, XRG 0.073 m· d-1 , seedling height 2.57 m; DE August 20, seedling height 3.22 cm; LG 37 days, total annual growth 4.09 m. The diameter and height of total annual growth are distinctively correlative with XRG respectively.