| As one of trees in Zelkova Spach genus of Ulmaceae family, Zelkova serrata(Thunb.)Makino is an excellent timber species and beautiful landscaping material with hard wood Property and beautiful autumn red leaves. This paper carried out cutting test taking semi woody shoots as materials and made analysis of the influence of the different exogenous hormones and its concentration and the physiological state in different collecting days on the formation of adventitious root in order to screen the best rooting treatment. Based on this, the study focused on the dynamic changes over content of nutrients, total phenol and endogenous hormone and enzyme activity in the process of rooting and relationship with rooting only to provide technical support and physiological basis so as to maintain the good characters of Zelkova serrata parent.The main conclusions were as follows:(1) The cuttings test with NAA and IBA different concentration processing softwood in September showed that Zelkova serrata?s rooting ability was weak if not treated by plant growth regulators.The exogenous hormone treatment can significantly improve its rooting characteristics. Different hormone treatments produced different rooting effects. NAA treatment was less effective than IBA, of which cuttings treated with 1000 mg·L-1 IBA owned highest rooting percentage for 61.2 %, shortest rooting time for18 d,and most rooting number up to 9.65. IBA 1000 mg·L-1 for Zelkova serrata Cuttings Propagating was the optimum.(2) Based on it, the optimum cutting date was tested for the sake of exploring the possible relationship between root formation and initial nutrient supply such as soluble carbohydrate and nitrogen, among which August 10 th was the best date in terms of adventitious root formation with rooted percentage 89.5 %,start time of rooting 10 d,average root numble12.5 and mean root length 5.3 cm; July 10 th inferior date and June 10 th the last one. During these 3 periods, the levels of soluble carbohydrate presented significant difference and the growing trend were positively correlated with rooting characteristics as a whole, while the change of nitrogen contents was not obvious in spite of decreasingtendency, and was basically contrary to rooting performance.T he C/N value was positively correlated with rooting rate and the correlation coefficient was above 0.99, so it can use the soluble sugar content or the C/N value as the criterion for the choice of cutting.(3) Trees whose age is within 5 years is also suitable for cutting propagation under good managemennt. Softwood cuttings from mother trees of 3 years were treated by IBA 1000mg·L-1 in early Augest, and its rooting rate reached 92.67 %.(4) Zelkova serrata hardwood cuttings was difficult to root. Its rooting improvement was not significant in spite of exogenous hormone stimulation. The best treatment with IBA 500mg·L-1 produced survival rate of 28.89 % only, which may be related to the higher content of phenolic compounds and unbalanced endogenous hormonesinhibiting rooting.(5) IBA treatment accelerated the nutrient metabolism process in shoots, and the changing shows certain regularity. Soluble sugar and soluble protein content changing trend was consistent with N shape, rising before callus formation, declining rapidly from callus formation to formation of adventitious root, and slowly rising after complete plant was formed. Total nitrogen decreased slowly, and then rose after adventitious root formation slowly, the overall changing was steady; The starch content decreased before rooting, and then rose, so the overall changing trend was in form of V; The change of C/N was same as soluble sugar basically due to steady changing of total nitrogen. The changing tendency of nutrients with water control treatment was similar to IBA treatment, however, its variation was less than hormone treatment group, and its time values reaching the valley or peak was later than IBA treatment group. The results indicated that IBA treatment promoted nutrients increasing or decreasing, transportation, transformation in shoots so as to improve rooting characteristics.(6) The measured test over oxidase activity in the phloem of Zelkova serrata cuttings showed that the activity of IAAO and POD increased before adventitious root emergence to remove redundant IAA and promote inducement of root primordium, and then decreased smoothly during adventitious root elongation with inverted "V"- an single peak curve. Water control treatment was similar to IBA treatment. CK peak delayed 8 d; PPO activity firstlyincreased and then decreased, and the increase of PPO activity was in favor of reducing the inhibitory effect of phenolic substances on rooting; And IBA treatment could improve SOD activity in early stage of cutting propagation effectively, promote induction of adventitious roots and lower the POD activity in late stage,so as to elongate and increase adventitious rootsand form complete plants.(7) The total phenolic compounds content in phloem rapidly declined before formation of adventitious roots with IBA treatment, followed by a slow rise, overall control group showed a higher level and valley value appeared later. The occurrence of adventitious root is the result of interaction among endogenous hormone regulation. IBA treatment increased the content of IAA, GA and ZR and decreased t content of ABA, promoting the occurrence of adventitious roots. Variation of IAA, GA, ZR content waspositively related to rooting performancethe and ABA was negatively related. Except ABA, the endogenous hormones ontent in control group was low and stable. When IAA/ABA value was high, it was conducive to adventitious root primordium induction, so it could be one of the basis on rooting level. |
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