毛白杨优树选择原则和方法的研究

The Principle and Method of Plus Tree Selection in Populus tomentosa

避免优树的重复是毛白杨选优的重要原则，可通过以下措施基本实现：①将现实毛白杨群体分为老树、自然类型、普通毛白杨和野生资源，然后在各类中分别选优；②以物候、形态等性状鉴别优树是否属同一基因型；③用同工酶等生理指标进行鉴定。对于老树，不评定生长量，作为基因资源全部入选；对于自然类型、普通毛白杨和野生资源，可进一步分为散生木、行进树和片林，然后分别评定生长量。散生木用绝对值评选法；行道树用小标准段法或绝对值评选法；片林用小标准地法，当通过形态和物候等性状的观察，确信片林中候选树周围为不同无性系时，也可用优势木对比法。通过１０４７株毛白杨优树生长量的分析，得出了选优的绝对值标准如下：１０年生左右时，年均胸径生长量２．５ｃｍ以上，年均树高１．３ｍ左右，年龄每增加１０ａ，年均胸径生长量约降低０．３ｃｍ，但年均树高都为１．０ｍ左右。

No repeat of plus trees is the main principle in the plus-tree selection of Populus tomentosa, whichcan be attained radically by the follows;①dlvide the present population of Populus tomentosa into old trees,natural types, normal trees and wild resotirees,then select plus trees in each type; ②exam plus trees tisingphenological and morphological characteristics;③exam plus trees by physiological method such as isozymeanalysis.The old trees are all selected as gene resources, but it should turn the other three types into individualtree,row plantation and block plantation in the comparison of growth. Only the absolute value judgment can beused for the individual tree, but small section method of absolute value judgment are all adapted to the rowplantation, and small plot method to the block plantation。If the trees surrounding the candidate tree are un-doubtly from different clones,dormanent tree comparison method can also be used for block plantations, Bystudying the growth imformation of 1047 plus trees of populus tomentosa, it is proposed that the standards ofthe absolute value judgment are as follows: D. B. H and height per year are over 2.5 cm and 1.3 m at abotit10-year-old, with the age of tree increasing 10 year, the D,B,H per year will diminish 0.3 cm,but the heightper year is still 1.0m。