两个菊花品种扦插生根过程及其插穗碳氮营养和内源激素的变化

Cuttings rooting process and changes in carbohydrate,nitrogen and endogenous hormone levels during the rooting of two chrysanthemum cultivars

以2个扦插生根能力不同的菊花品种雨花星辰和天坠玉露为材料,测定了扦插过程中叶片和茎的碳氮营养含量变化和插穗皮部内源激素IAA、ABA、GA3和iPA含量的变化。结果表明:通过形态解剖观察,雨花星辰和天坠玉露根原基形成时间不同,分别在扦插6d和14d后观察到根原基原始细胞,并于12d和20d后开始生根。扦插生根前2个品种叶片和茎的碳水化合物含量总体呈现先下降后上升的趋势,生根后再度下降,而氮素含量呈较稳定的下降趋势;2个品种相比,易生根品种插穗有较高的糖/氮;扦插过程中,光合产物优先在茎积累,C/N在茎中先回升,生根后茎中C/N显著高于叶片。扦插生根过程中,内源激素含量也存在显著变化:IAA和ABA含量在根原基形成期均出现上升,但生根过程中IAA/ABA变化不显著,易生根品种IAA/ABA较高;扦插过程GA3/ABA先上升后在根原基形成期下降,iPA含量在整个生根过程中不断下降引起IAA/iPA上升。提示:碳水化合物代谢及生根部位内源激素变化与生根过程密切相关。

The carbohydrate and nitrogen content in the leaves and stems,and endogenous hormones content （IAA,ABA,GA3 and iPA） in the phloem of the basal stem were investigated in cuttings of two chrysanthemum cultivars Yuhuaxingchen and Tianzhuiyulu differing in the rooting capacity.The morphological and anatomical observations showed that the time of root primordium formation was different between two cultivars.Root primordium initial cells were observed on 6 d （Yuhuaxingchen） and 14 d （Tianzhuiyulu）,respectively.Rooting occurred afterwards 12 d （Yuhuaxingchen） and 20 d （Tianzhuiyulu）,respectively.Changes in carbohydrate content overall showed that carbohydrate content decreased firstly,then increased,whereas declined after rooting.The nitrogen content decreased constantly throughout the process of rooting.Moreover,cuttings of the cultivar easy to root showed higher ratio of sugar to nitrogen both in leaves and stems.Preferential accumulation of photosynthetic assimilates in stems caused an earlier rise in C/N in stem than in leaves during rooting.After rooting,the C/N in the stem was significantly higher than that in leaves in two cultivars.In addition,the content of endogenous hormones changed greatly during the process of rooting.IAA and ABA content increased remarkably during the root primordium formation,however,the ratio of IAA to ABA remained relatively stable during the whole process of rooting.The ratio of IAA to ABA was higher in cultivar easy to root compared with the other one.GA3 /ABA rose at the early stages,but decreased in both cultivars after root primordium formed.iPA content kept decreasing throughout the whole process,and as a result,the ratio of IAA to iPA increased correspondingly.It inferred that the metabolisms of carbohydrates,nitrogen and endogenous homologous in cuttings were strongly associated with rooting process.