莫继有 兰俊 罗建中 吴满芬 彭智邦

摘 要： 选定组配树种对桉树杂交种的特性起决定作用，但不同种间杂交种的生长表现常常不容易预测。为掌握华南地区桉树重要树种间杂交种的生长特征，促进桉树杂交育种的精准化，该文以父本为混合花粉的人工杂交种为遗传材料，以尾叶桉×巨桉为对照，进行了尾叶桉与桉树窿缘组树种（布拉斯桉、细叶桉、钝盖赤桉、昆北赤桉）的4种组配杂交种的生长特征研究。结果表明：在材积生长量上，尾叶桉与窿缘组树种杂交种低于尾叶桉×巨桉，但其内部树种间差异显著（P<0.05），其中尾叶桉×昆北赤桉具有显著优势;尾叶桉与窿缘组树种杂交种的树高、胸径均显著小于尾叶桉×

巨桉，但其高径比显著大于尾叶桉×巨桉（P<0.05）;尾叶桉与窿缘组树种杂交种具有高的和一致的保存率，且在不同组配间、家系间（组配内）均无显著差异，5年生值为84.4%～89.6%;尾叶桉与窿缘组树种杂交种的5年生材积的平均变异系数约为64%，组配间、家系间差异大，都大于尾叶桉×巨桉。尾叶桉与窿缘组树种杂交种的速生性、树形等与尾叶桉×巨桉间存在显著差异，尾叶桉与窿缘组树种杂交种的組配、家系间具有显著的生长差异，可为桉树遗传改良提供丰富的多样性。

关键词： 种间杂交种， 生长， 尾叶桉， 窿缘组， 混合花粉子代

中图分类号： Q945

文献标识码： A

文章编号： 1000-3142（2021）04-0631-09

Abstract： Deciding crossing parental species will determine characteristics of eucalypt hybrids， but the growth performance of hybrids from different parents is hard to predict. Understanding the growth features of hybrids between important eucalypt species in South China will greatly improve hybrid breeding accuracy. We studied the growth characteristics of hybrids between Eucalyptus urophylla and four Section Exsertaria species/subspecies （E. brassiana， E. tereticornis， E. camaldulensis var. obtusa and E. camaldulensis subsp. simulata） with E. urophylla × E. grandis （UG） hybrids serving as a control， of which the male parents were polymix of 10 plus trees were studied. The results were as follows： Stem volume growth in E. urophylla × Section  Exsertaria species （UES） hybrids were significantly lower than UG. And there were significant differences between the UES hybrids （P<0.05）， among which E. urophylla × E. camaldulensis  subsp. simulata demonstrated significant advantages. DBH and Ht of UES were significantly lower than those of UG， but with height-diameter ratios were significantly higher than UGs （P<0.05）， with 5-year-old values approximately 150 and 130， respectively. UES had high and uniform preserve rates， and no significant differences due to either species or family （within species） level. Their 5-year-old values were 84.4%-89.6%. The UESs coefficient of variation （CV） of 5-year-old stem volume had an average of 64%， yet significantly differed between species was higher than that of the UGs. UES was significantly different from UG on volume growth and tree shape， and the significant differences between UES species and families could provide substantial diversity to eucalypt genetic improvement.

Key words： interspecific hybrids， growth， Eucalyptus urophylla， Section Exsertaria species， polymix progeny

桉树种间杂交因可以聚合多个树种的特性，甚至获得杂种优势，在桉树育种中广泛应用，特别是在亚热带、热带桉树的遗传改良中尤其成功（Potts & Dungey，2004），是目前世界上桉树人工林大国如巴西、中国、南非等的主要育种方法（罗建中，2012;Kullan et al.，2012;Madhibha et al.，2013）。种间杂交过程是不同树种基因的重组，会对一系列数量、质量等性状产生不同程度的影响，产生不同于亲本的新表现型。虽然杂交种的性状大多介于亲本之间（Potts & Dungey，2004），但在特性不同的树种进行交配时，其子代的生长特点并不容易预测，例如，木材生长量、用材率等经济性状，有很多杂种优势的结论，但也有杂种劣势的结果（Assis，2000;Butcher & Williams，2002）。有研究发现杂交种的生存能力有随着亲本分类学距离的增加而降……