In order to study the growth traits of Catalpa bungei clones in various growth periods during the nursery stage so as to provide a theoretical basis for genetic improvement,the authors matched the height and diameter in nursery stage by Logistic equation.The results showed that the mean height of clones was 325.19 cm,with the range of 253.48-402.88 cm,the mean basal diameter of clones was 4.29 cm,with the range of 3.61-5.05 cm.The height increment could be divided into two stage,i.e.the early-growing period and the fast-growing period,while the basal diameter increment could be divided into three stage,i.e.the early-growing period,the fast-growing period and the late-growing period.The beginning of fast-growing period,the end of fast-growing period,the duration of fast-growing period,and the daily mean height increment in fast-growing period were May 26-July 2,September 11-October 15,72-128 days,and 1.70-2.88 cm,while that for basal diameter increment were May 9-June 5,August 23-October 3,95-138 days,and 0.021-0.032 cm.The variation of traits in fast-growing period was more significant.The height and basal diameter were significantly correlated to their increments in earlygrowing period(0.744,0.928),fast-growing period(0.965,0.804),and their daily mean increment in fastgrowing period(0.733,0.811).
