楸树嫁接繁育适宜砧木的选择

Selection of the suitable rootstocks for grafting and breeding of Catalpa bungei

【目的】分析不同砧木嫁接楸树无性系的保存率、接穗生根率、生长和材性性状差异,以及无性系与砧木的互作效应,筛选楸树无性系的适宜嫁接砧木,旨在为楸树良种嫁接壮苗规模化繁育提供理论依据。【方法】以梓属不同树种为砧木嫁接的11年生楸树无性系对比试验林为材料,采集3个楸树无性系的接穗,分别用5种砧木(楸树、灰楸、梓树、滇楸和黄金树)嫁接育苗并造林,开展嫁接无性系的保存率、接穗生根率、生长、材性性状差异分析。【结果】5种砧木中,以滇楸为砧木嫁接无性系的保存率最高(74.1%),其次是梓树和灰楸(63.0%和59.3%),而以黄金树为砧木嫁接无性系的保存率最低(29.6%);以楸树为砧木嫁接无性系的接穗生根率最高(100%),其次是滇楸和灰楸(77.8%和66.7%),黄金树为砧木的生根率最低(33.3%);不同砧木间,嫁接无性系的胸径、树高、Pilodyn值、弹性模量差异显著或极显著,且(树高除外)存在显著的砧木与无性系的互作效应;灰楸为砧木时,无性系的树高和胸径最大(14.9 m和17.5 cm),以滇楸和楸树为砧木时的树高和胸径均较大(14.8 m、15.5 cm和13.8 m、15.8 cm),而以黄金树为砧木时,嫁接无性系的树高和胸径最小(12.8 m和10.9 cm);通过Pilodyn值间接预测,灰楸为砧木时楸树无性系的密度最大(23.3 mm),梓树和楸树次之(23.9 mm和24.4 mm),滇楸和黄金树为砧木时均较小(25.6 mm和25.2 mm);5种砧木中,以灰楸为砧木的弹性模量最大(7.0 GPa),其次是梓树和楸树(6.6 GPa和6.5 GPa),滇楸最小(6.1 GPa)。根据不同砧木嫁接无性系的保存率、接穗生根率、树高、胸径、Pilodyn值和弹性模量综合筛选,以灰楸和楸树为砧木,楸树无性系的生长、材性、保存率、接穗生根率都较好。【结论】楸树无性系嫁接繁育的适宜砧木为灰楸和楸树,黄金树不宜作砧木。

【Objective】This study was aimed to screen the suitable grafting rootstocks for Catalpa bungee,via analyzing the preservation rates,scion rooting rates,growth and wood properties of different rootstocks grafted Catalpa bungei clones,as well as the interaction effect between the clones and rootstocks.These results will provide a theoretical basis for the large-scale breeding of grafted C.bungei.【Method】Three scions of C.bungei clones were collected,and grafted with five rootstocks(C.bungei,C.fargesii,C.ovata G.Don.,C.fargesii f.duclouxii and C.speciosa(Barney)Engelm)for afforestation.Afterwards,the analyses of preservation rates,scion rooting rates,differences in growth and wood properties were conducted.【Result】Among the 5 kinds of rootstocks,the preservation rate of the clones grafted with C fargesii f.duclouxii was the highest(74.1%),followed by C.ovata(63.0%)and C.fargesii(59.3%),while the preservation rate of the clones grafted with C.speciosa was 29.6%.The scion rooting rate of the clones grafted with C.bungei showed the highest(100%),followed by C fargesii f.duclouxii(77.8%)and C.fargesii(66.7%),while the rooting rate of the clones grafted with C.speciosa was the lowest(33.3%).The results revealed significant differences in diameter at breast height,tree height,Pilodyn value,and elastic modulus of the grafted clones.In addition,all these results showed a significant interaction effect between the rootstocks and the clones,except for tree height.When grafted with C.fargesii,the height and diameter at breast height of the clones were the largest,showing 14.9 m and 17.5 cm,respectively.When C.fargesii f.duclouxii and C.bungei were used as the rootstocks,the tree height and diameter at breast height were 14.8 m/15.5 cm,and 13.8 m/15.8 cm,respectively.However,the minimum tree height and diameter at breast height came from the clones grafted with C.speciosa,showing 12.8 m and 10.9 cm,respectively.According to the Pilodyn values,the density of the grafted C.bungei clones was the largest when C.fargesii was used as the rootstock,which was 23.3 mm,followed by C.ovata(23.9 mm)and C.bungee(24.4 mm).When grafted with C.fargesii and C speciosa,the clones were both small,showing 25.6 mm and 25.2 mm,respectively.Among the five types of grafted clones,the ones grafted with C.fargesii had the largest elastic modulus showing 7.0 GPa,followed by C.ovata(6.6 GPa)and C.bungei(6.5 GPa),while the clones grafted with C.fargesii f.duclouxii was the smallest(6.1 GPa).Taking all the results together,the data revealed that in comparison with other clones,the clones grafted with C.fargesii and C.bungei showed better growth.【Conclusion】The suitable rootstocks for grafting and breeding of C.bungei clones are C.fargesii and C.bungei,while C.speciosa is not suitable for its grafting.