湿地松不定根诱导中内源激素水平变化

Changes in Endogenous Hormone Levels during Adventitious Root Induction in Pinus elliottii

以4年生湿地松Pinus elliottii母株上所采穗条为试验材料,通过扦插育苗方法,分析不定根诱导过程中插穗根茎解剖构造与内源激素水平的变化。结果表明:湿地松无潜伏根原基,生根诱导20天产生不定根原基,诱导45天形成不定根。与诱导45天有根苗相比,诱导45天无根苗具有根原基,但根原基周围薄壁细胞中积累了大量脂性物质,不定根发育受阻。内源IAA、ABA、GAs与不定根诱导密切相关,ZR影响不明显。从生根过程中激素水平变化模式来看,IAA先下降而上升、ABA直线上升、GAs先上升后下降。不定根诱导45天的无根苗与有根苗相比,IAA、ABA、ZR水平无显著差异,但无根苗中GAs显著高于有根苗。在生根诱导20天后,以50 mg/L GAs生物合成抑制剂多效唑(PBZ)喷施针叶,能显著提高插穗生根率和根条数。初步认为,湿地松不定根诱导应采用两步生根法,前期(扦插0~20天)采用IAA、GAs、ABA组成的复合生长调节剂促进根原基形成,后期(扦插21~45天)施加PBZ以促进不定根的发育。

In order to provide scientific reference for the improvement of rooting ability of Pinus elliottii,the changes of anatomical structure and endogenous hormone levels of cuttings in adventitious root induction were analyzed by cutting.The results showed that there was no latent root primordium in P.elliottii.Adventitious root primordium was generated after 20 days of induction.Adventitious root was formed after 45 days of induction.After 45 days of rooting induction,compared with rooted cuttings,root-free cutting had root primordia,but a lot of lipid substances that accumulated in parenchyma cells surrounding root primordia.Adventitious root development was blocked.Endogenous IAA,ABA and GAs were closely related to adventitious root induction,while ZR did not significantly affected.The pattern of hormone levels during rooting showed that IAA decreased first and then increased,and ABA increased linearly,and GAs increased first and then decreased.There were no significant differences in IAA,ABA and ZR levels between root and rootless cuttings after 45 days of adventitious root induction,and GAs in rootless cuttings was significantly higher than that in root cuttings.After 20 days of rooting induction,spraying needles with 50 mg/L PBZ,which was a GAs biosynthesis inhibitor,could significantly increase the rooting rate and root number of cuttings.It was suggested that the adventitious roots of P.elliottii should be induced by two-step rooting method.In the early stage (cutting 0-20 days),a combined growth regulator composed of IAA,GAs and ABA should be used to promote the formation of root primordia,and in the later stage (cutting 21-45 days),PBZ can be added to speed up the development of adventitious roots.