自1977年以来,我所开展了柳桉(Eucaly-ptus Saligna)×隆缘按(E. exserta)、隆缘桉×柳桉、柳桉×大叶桉(E. robusta)、隆缘桉×巨桉(E. grandis)、隆缘按×大叶桉5个人工杂交组合的育种试验。各年度获得的杂交种子和父母本以及对照种的种子,分别于1978年5月用容器育苗,造林。试验林采用随机排列,重复4次。1980年5月测定的数据表明:除柳桉×大叶桉这个组合外,其他4个杂交组合的子代(F_1,F同)都具有明显的杂种优势(见表 Since 1977, Eucalyptus Saligna × E. exserta, Eucalyptus grandis × Eucalyptus globulus, E. robusta × Eucalyptus grandis × Eucalyptus grandis × Eucalyptus grandis (E. grandis), the Longyuan × Eucalyptus grandiflora Eucalyptus 5 artificial breeding combinations of breeding experiments. The seeds of the hybrid seeds and parents and the control seeds obtained each year were raised in containers in May 1978 and reforested. The experimental forests were randomly arranged and repeated 4 times. The data measured in May 1980 showed that the progenies (F_1, F) of the other four hybrid combinations all had obvious heterosis except the combination of Eucalyptus urophylla × E. grandis (Table