Phenotypic Variation Of Acer Truncatum Bunge

Acer truncatum belongs to genus Acer of Aceraceae family. It is one endemic species in China with widely distributing to north temperate area, especially in the valley of Yellow River. A. truncatum is a tree species of multiple uses with beautiful crown shape and coloured leaves in autumn and winter. There are high content of flavonoids and chlorogenic acid in the leaves, vegetable tannin in the pericarps, and edible and officinal oil in the seeds of A. truncatum. Therefore, A. trunctum was widely studied and introduced into other places as a commercial tree.In 1998, A. truncatum was introduced into Yunnan plateau and established a large scale plantation. In order to selecting and breeding varieties to adapt Yunnan plateau, it is very important that understand population variation in established A. truncatum plantations. From 2004 to 2006, the special aspects were investigated and studied on growth pattern of branches, population variation of seedlings, vegetative variation of adult trees, the pattern of blossoming and fructification, relativities among above mentioned traits among established A. truncatum plantations in Kunming area. Based on ivestigation and analyis of foregoing aspects, morphological variation of fruits and variance type was compartmentalized. The study results were showed as followings:1) In Kunming area, A. truncatum grows very slow before May, then its reaches growth peak (including height growth and diameter growth) in June and July For one-year-old seedlings left in the nursery and transplanted to fields. The shoots of A. truncatum trees occur in later February, then fast growth phase of the trees appears in April. For diameter growth, there were two growth peaks in March and June, and for height growth, only one growth peak was examined in April. Branch differentiation was obvious. There are two types of branches distinguished long-branch and short-branch. Short-branch ceases height growth in May. However, its diameter grew synchronously with that of long-branch. For adult trees, all branches (including short- and long-branch) blossom in next spring.2) The growth performance of different aged seedlings showed significant variation. The variation coefficient of seedling height, basal diameter and number of leaves were 47.84%~70.89%, 42.51%~57.50% and 60.70%~68.14% respectively.3) For the population of adult trees, all vegetative traits, including basal diameter, height, crown width, and the number of branch and leaves, showed significant variation. The variation coefficients were from 17.92-65.05%. In addition, there were significant positive correlations among all vegetative traits. Of which the correlative coefficient between the numbers of branches and leaves was 0.948, and 0.833 for the height and basal diameter. 4) In Kunming area, although the initial blossom of some trees occurred first blossomed in later February, which of most trees was observed in March. About 50% fruit were aborted before the time of ripeness in October. The flowers and fruit were distributed in approximately equal proportion in four orientations of a crown, but of which more than 70% were distributed on the upper level branches and less than 30% on the lower branches. There was significant positive correlation between the numbers of flowers and fruit with 0.643 of correlation coefficient, while there was no correlation between the number of fruit and branches, also the some as leaves. In the adult tree population, some trees developed into vegetative type and others developed into reproductive type.5) There were extreme variations among the traits of fruit from different trees. For 9 index of fruit, the variation coefficients from 7.83- 51.73%. There were obvious positive correlation between weight and other traits of fruit, of which the correlative coefficients between weights of fruits and seeds was up to 0.943. There were obviously positive correlations between weight of seeds and weight of fruit, thickness of fruit and seeds or width of fruit.6) According to the growth characteristics, the variance types of A. truncatum were classified into vegetative type and reproductive types. The reproductive types were classified into wide wing type, small wing type and big wing type based on fruitage shape. The plus-trees of leaf oriented one were selected from vegetative type mainly based on the number of branches and leaves, while the plus-tree of fruitage oriented one were selected from reproductive types mainly according to the number of fruitage and the thickness of fruitage.7) The leaf oriented plus-trees were selected, which were individual tree of No. 7, 75, 38, 80 and 103 based on the data of comparison and analysis. And the individual tree of No. 101, 100, 136, 146 and 147 were selected as fruit plus-tree.