尾叶桉与窿缘组树种间杂交种的生长特征

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(P0.05),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(P0.05);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组配、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。

Growth characteristics of hybrids between Eucalyptus urophylla and Section Exsertaria species

Decidingcrossingparentalspecieswilldeterminecharacteristicsofeucalypthybrids,butthegrowthperformanceofhybridsfromdifferentparentsishardtopredict.UnderstandingthegrowthfeaturesofhybridsbetweenimportanteucalyptspeciesinSouthChinawillgreatlyimprovehybridbreedingaccuracy.WestudiedthegrowthcharacteristicsofhybridsbetweenEucalyptusurophyllaandfourSectionExsertariaspecies/subspecies(E.brassiana,E.tereticornis,E.camaldulensisvar.obtusaandE.camaldulensissubsp.simulata)withE.urophylla×E.grandis(UG)hybridsservingasacontrol,ofwhichthemaleparentswerepolymixof10plustreeswerestudied.Theresultswereasfollows:StemvolumegrowthinE.urophylla×SectionExsertariaspecies(UES)hybridsweresignificantlylowerthanUG.AndthereweresignificantdifferencesbetweentheUEShybrids(P<0.05),amongwhichE.urophylla×E.camaldulensissubsp.simulatademonstratedsignificantadvantages.DBHandHtofUESweresignificantlylowerthanthoseofUG,butwithheight-diameterratiosweresignificantlyhigherthanUG''s(P<0.05),with5-year-oldvaluesapproximately150and130,respectively.UEShadhighanduniformpreserverates,andnosignificantdifferencesduetoeitherspeciesorfamily(withinspecies)level.Their5-year-oldvalueswere84.4%-89.6%.TheUES''scoefficientofvariation(CV)of5-year-oldstemvolumehadanaverageof64%,yetsignificantlydifferedbetweenspecieswashigherthanthatoftheUG''s.UESwassignificantlydifferentfromUGonvolumegrowthandtreeshape,andthesignificantdifferencesbetweenUESspeciesandfamiliescouldprovidesubstantialdiversitytoeucalyptgeneticimprovement.