优树选自不同的立地条件,优树间质的差异难于互作比较,加之当前优树主要是根据表型选择,表型是基因型加环境,即环境条件特别是水肥条件的好坏,使表型大受影响,这就往往使基因型一般的树木,因植点上水肥等条件的差异,而表现优异,被选为优树。加上目前选优方法不够完善,使这种基因型一般的树木,在选出的优树中占有相当比例。因此,用未经测定优树直接用于生产,其增产效果是不稳定的(没有把握)。无性系测定,即把不同立地条件下选出的优树(无性系)栽植于同一立地条件,以消除 The superior trees were selected from different site conditions, and the differences between the superior trees were difficult to be compared with each other. In addition, the current optimal tree was mainly based on phenotypes. The phenotype was genotype plus environment, that is, the environmental conditions, especially the conditions of water and fertilizer, So that the phenotype greatly affected, which often genotypes of trees, due to the site of fertilizer and other conditions on the differences, and outstanding performance, was selected as superior tree. Coupled with the current optimization method is not perfect, so that the genotypes of the trees in the selected tree account for a considerable proportion. Therefore, the use of unmeasured trees directly used for production, the yield effect is not stable (not sure). Clone determination, that is, under different site conditions selected trees (clones) planted in the same site conditions to eliminate