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赤桉優勢木無性繁殖方法之比較
Comparison of Different Methods of Vegetative Propagation of Eucalyptus camaldulensis Plus Trees
摘要
自赤桉6或7年生種原試驗地與3年生單親後裔試驗地的造林木中，選出高生長量及表型優良之單株各為85及40株，分別取前者之成熟樹枝穗、後者砍伐後之根株萌蘖、與嫁接於幼年砧木後之成熟接穗進行扦插，及微體繁殖之芽體進行發根檢定，以比較不同材料之發根力。結果成熟枝穗之扦插發根率僅0.28%，有3.5%的營養系發根。但從3年生單親後裔試區伐倒後萌芽枝條之扦插發根率有31.6%，共有74%的營養系發根成苗。成熟樹枝穗頂接於2年生赤桉砧木之接活率50%高於嫁接於1年生砧木的2.1%，接活率雖不高，但有95%的營養系均能接活。在嫁接一年後，接穗與砧木間之不親和力嚴重，最後僅剩43.5%的營養系存活，採其接穗的枝條扦插仍無法發根。微體繁殖系利用成熟樹與萌蘖樹枝條的頂芽及帶腋芽的節為培植體進行試管內培養，不管培植體的來源是成熟樹或萌蘖樹的枝條，72%營養系均可在試管內培養存活。但在持續的繼代培養後，由於有些來自成熟樹的培植體存活數少且生長緩慢不易存活，最後在試管內的存活率僅剩62.8%，而來自萌芽條的營養系則因存活數多且活力較強，96%的營養系均能存活。由於利用扦插、嫁接與微體繁殖出來的營養系並非完全相同，因此結合此三種方法繁殖出所有的營養系是可行的。組培苗經發根後，與扦插苗一同栽植於苗圃以供建立為採穗園。經栽植1年後，組培苗表現出比扦插苗有顯著的高生長。
並列摘要
Among four 6- or 7-year-old plantations of provenance trial and a 3-year-old plantation of half-sib trial of Eucalyptus camaldulensis, 85 and 40 plus trees with fast-growing phenotype were selected resepectively. Evaluation was made of the effects on rooting ability of cuttings taken from adult shoots of provenance trial trees, coppice shoots of felled half-sib trees and grafts of adult scions grafted onto young rootstocks, and in vitro shoots from adult and coppice explants. Rooting occurred in 0.28% of cuttings and 3.5% of clones of adult shoots. In contrast, 31.6% of cuttings and 74% of clones of coppice shoots rooted. Survival of adult scions grafted onto 2-year-old rootstocks was 50% compared to only 2.1% for those grafted onto 1-year-old rootstocks. Although 95% of clones showed initial success after being grafted one month, only 43.5% of clones had survived one year later indicating serious incompatibility. Moreover, cuttings from these grafted shoots failed to root. Micropropagation was conducted with explants of shoot tips and nodal segments from both adult and coppice shoots. About 72% of clones were established as proliferating shoot cultures regardless of the explant source. However, survival of clones from adult explants decreased to 62.8% after repeated subculturing. This falure clones had few survival explants in vitro with poor growth that difficult to maintain in subcultures. In comparison, 96% of clones derived from coppice explants were maintainable and grew vigorously in subculturing. After 9 months of subculturing shoots, whether of adult or coppice origin, all rooted well in a suitable medium. In view of the finding that the clones propagated by cuttings, grafting, and micropropagation were not the same, it is recommended that a combination of these three techniques be considered to maintain most clones. Rooted shoots from in vitro cultured clones were established in the nursery to serve as a scion garden. Tissue-cultured-derived plants were significantly taller than cutting-derived plants after one year.