Soft-wood Cutting Propagation Technique And Rooting Physiology Research Of Amygdalus Pedunculata

Amygdalus pedunculata is an woody oil plant,uniquely distributed in the arid and semiarid areas of northwest China.For the excellent resistance properties to cold drought,windbreak and sand-fixation ect,and gorgeous and beautiful flower,it has higher ecological and economic values in improving the regional ecological environment and promoting local economic development.At present,the seedling production of Amygdalus pedunculata is given priority by seed propagation.However,there are some problems with this breeding way,such as offspring trait differentiation,in addition,the setting percentage of Amygdalus pedunculata is very low in natural conditions,meanwhile,the collection of superior seed sources is difficult.And all of this lead to seed propagation can not meet the requirement of the Amygdalus pedunculata industry development.For the realization of clone preservation and large-scale protection of the elite Amygdalus pedunculata resources,the one-year healthy semi-lignified twigs were selected as experimental material,the effects of medium types,plant growth regulating substance types and concentration,cuttings types,treatment times and management systems on cutting propagation were systematically investigated,and then the optimal treatment combinations were screened.Based on the cutting propagation technique,the dynamic changes of endogenous hormones,soluble protein,soluble sugar,peroxidase(POD)activity and malondialdehyde(MDA)content were further studied during the cutting rooting process,revealing the physiological mechanism of cuttings rooting of Amygdalus pedunculata.The main results were as following:(1)After indole-3-butyric acid(IBA)treatment,the green-wood cuttings rooting types of Amygdalus pedunculata was given priority to with mixture rooting type(58.0%),followed by with callus rooting type(28.3%)and skin rooting type(10.8%).The rooting rate of cuttings was significantly improved when treatment with IBA.At 6 d after cutting,the root primordia bloomed,and the base of the cuttings was enlarged;from 6 to 12 d the adventitious roots formed,and from 12 to 26 d rooting cuttings peak,between 26 and 40 d root constantly grow and mature.The study showed that the four factors affecting the rooting rate of Amygdalus pedunculata were,in turn,types of plant growth regulating substance,types of cuttings,plant growth regulating substance concentrations and the treatment times of cuttings;The best rooting effect of cuttings in mixed matrix was V(perlite): V(peat)=3:1,moreover,the optimal rooting effect was obtained for the cuttings from the upper of twigs and treatment with 1500 mg·L-1 IBA for 10 second,with the best treatment combination,the soft-wood cuttage rooting percent of Amygdalus pedunculata was higher in greenhouses cutting propagation system and all-optical spray cutting propagation system(were 98.67% and 97.8% respectively),and the root quality of cuttings was good,which could meet the requirements of large-scale nursery during the cutting propagation of Amygdalus pedunculata.(2)During rooting of cuttings,the rising up of the content trans-zeatin-riboside(ZR)and gibberellin(GA3)were beneficial to promote adventitious root formation;indole-3-acetic acid(IAA)content and IAA/ABA ratio were positively correlated with rooting ability of cuttings,while(abscisic acid)ABA content was negatively correlated with rooting ability of cuttings.The soluble sugar and soluble protein in the cuttings were the energy and material sources of various physiological and biochemical reactions during the process of rooting,and the trends of the two substances changes were corresponding to the demand of the rooting process,so the increase of the soluble sugar and soluble protein contents were favorable to the rooting of the cuttings.POD activity is closely related to the rooting of cuttings,and the increase of POD activity was beneficial to the induction and formation of adventitious roots in the process of rooting.MDA is negatively correlated with the antioxidant capacity and anti-aging ability of cuttings,and MDA content increased in the early cutting stage,but decreased in adventitious root formation period.Exogenous hormone IBA treatment regulated the content of endogenous hormones,nutrient level,MDA content and POD activity in the cuttings,which would benefit the promotion of the rooting of cuttings.