<正>对苏南杉木５０个优树自由授粉半同胞家系林１２ａ木材基本密度测定表明，优树子代有显著变异，家系间变异＞家系内变异。木材（基本密度）性状与树高有显著中等强度负遗传相关，与胸径、材积的负遗传相关不明显。性状变异的大小为树高＞胸径＞基本密度。供试群体中有９个家系子代生长和材性优于对照。经材积生长与材性性状两阶段独立选择法联合改良，选出句东２４、溧黄１、句１２、句１４四个优质高产的当地杉木优良家系，１２ａ材积遗传增益达１４．０％～４２．２％，基本密度遗传增益为０．９％～６．０％。这些优良家系为杉木定向改良应用提供了材料基础。

12 years old of offspring forest of 50 ellite trees of free-pullination half-sib families of the timber density of the measurement results showed that there are significant variances among offsprings of ellite trees,and the variances between families are bigger than the variances inside families. There is a mean negative genetic relationship between the characteristic of lumber density and tree height, and there is no negative genetic relationship between the timber density and brest diameter,volume.The size of characteristic variances is tree height >brest diameter>lumber density.Among the experiment group of the growth and wood feature’97 offspring of families were better than the check.