Model construction of seedling growth for hybrid clones of Populus tomentosa.

A total of 50 Populus tomentosa hybrid clones were used to analyse the variation of growth curve of tree height. The results showed that the growth curve of tree height shaped like “S冶and the coefficient of Logistic model was higher than 0.887. There were remarkable differences within different variation sources among the tree height of different clones (P 0.01). The average rapid growth point of poplar clones was the 176th day and the average rapid growth last for 44 days. Total increment of average tree height developed during rapid growth period was 31.43 cm, and 0.72 cm in one day. There was remarkable positive correlation between extreme k value and tree height, so k value was an important index for tree height estimated. The ultimately tree height was significant correlated with average tree height growth in rapid period.