Abstract:
Objective To study the growth rhythms of Toona ciliata seedlings from 18 provenances, to provide a scientific basis for breeding and screening high-quality T. ciliata provenance.
Method Heights and ground diameters of one-year-old T. ciliata seedlings from 18 provenances were regularly observed. Analysis of variance was performed using SPSS, and the genetic coefficients of variation (GCV) were obtained. The Logistic equations were used for fitting the growth curves of seedling heights and ground diameters, and for estimation of the growth parameters. The correlations between seeding height, ground diameter and geographical, ecological factors were investigated.
Result The GCV of seeding height and ground diameter of T. ciliata were 43.31% and 36.25% respectively. The geographic variations in two traits were mainly influence by longitude. The growths of the two traits were both in a "slow-fast-slow" pattern showing a similar "S" curve. Two growth peaks of each trait were observed. The determination coefficients of Logistic equations varied from 0.971 to 0.998 for T. ciliata from different provenances, and the fitting degrees reached significant levels. The growth of T. ciliata seedlings could be divided into three stages, including the early, fast and late growth stages. T. ciliata from different provenances had different starting and ending time for the three stages.
Conclusion There are great heredity potentials in seeding height and ground diameter of T. ciliata. Geographic variation trends of the two traits are obvious among different provenances. The seeding height and ground diameter grew faster for T. ciliata from western provenances compared to eastern provenances. There were significant differences in seedling growth rhythms. During the fast growth stage, the growths in seedling height and ground diameter for T. ciliata from eastern provenances lasted longer compared to western provenances, while the extent of growth of this stage and yearly growth were both smaller for the provenances from central China and east China.