Selection Of Superior Individuals Of Some White Chrysanthemums With Single Head For Cut-flower And Their Rapid Propagation By Culture In Vitro

'Jingcheng' is one of novel cultivars in single-headed chrysanthemum as cut flower,which has been introduced from Japan in recent years,'Jingcheng' can be planted in high-altitude mountain regions for cold-resistance,flowering during Tomb-Sweeping Days to fill market margins of 'Iwanohakusen' and 'Shenma'.To address shortage of high-quality plantlets,System of rapid propagation in vitro was developed with cuttings from protospecies plants of 'Jingcheng' as explant for providing high-quality plantlets and technical support to promote industrialization of'Jingcheng',which will play an important role on theoretical level and practical value.To overcome the disadvantages of 'Iwanohakusen' and 'Shenma'in production,some superior mutant individuals with few lateral buds,more petals and larger flower diameter were selected from the resulted mutants by treating top buds of cuttings of 'Iwanohakusen' protospecies with EMS as chemical mutation agent and by treating cuttings of‘Shenma,protospecies with 60Co-? rays as radiation sources.Genetic similarity between the superior mutant individuals and original cultivars was identified by IS SR molecular marker technology,These obtained superior individuals will provide new germplasm resources or raw materials for breeding of 'Iwanohakusen' and 'Shenma,,which has an important significance on saving labor cost in lateral bud removal and on increasing ornamental value and economic profits of 'Iwanohakusen' and 'Shenma'.The results were as follows:1.1.The system of rapid propagation in vitro of 'Jingcheng' was developed(1)Sterile plantlets were obtained in primary culture:Sterile plantlets were induced on media of primary culture using apical buds of cuttings and stem nodes with axillary buds as explants,sterilized by 0.1%HgCl2 as surface disinfectant.The results showed that apical buds are more suitable than stem nodes with axillary buds as explants in primary culture,the optimal medium was MS addition with 0.5 mg/L of 6-BA and 0.1 mg/L of NAA,and the average number of effective buds inducted was 5.87.(2)The subculture and propagation of buds:use stems with axillary bud of sterile seedlings,leaf cuttings and leafstalks induced from primary culture as explants,inoculate to MS mediums with different concentration of hormone combination,to induce adventitious bud or caespitose shoots.Experiments show that the best propagation medium for stems with axillary bud is MS+1.0 mg/L 6-BA+0.3 mg/L NAA,with multiplication coefficient of 6.92,the best propagation medium for leaf cuttings is MS+1.0 mg/L 6-BA+0.3 mg/L NAA,with multiplication coefficient of 3.59,and the best propagation medium for leafstalks is MS+1.5 mg/L 6-BA+0.15 mg/L NAA,with multiplication coefficient of 0.49.(3)Rooting culture of sterile seedlings:cut the rootless seedlings with growth consistence from propagation culture into cutting slips of 3 cm,inoculate to 1/2 MS mediums with different concentration of NAA or IBA,to induce rooting.Experiments show that different concentration of NAA or IB A can both induce rootless seedlings to root with rooting rate of 100%,with the increase of concentration of NAA or IB A,number and roughness of root increases,when concentration of IBA and NAA were at 0.5 mg/L,the effect of induced root of IBA is better than NAA,therefore,1/2 MS+0.35 mg/L IBA is optimum rooting medium..(4)Domestication and transplantation of rooting seedlings:rooting seedlings are not transplanted to matrix with different ratio of materials until experiencing different domestication time.Experiment results show that it only takes two days of domestication to make transplanting survival rate 100%,and the best transplantation matrix is turfy soil:vermiculite=1:1.2.To obtain superior mutant individuals of‘Iwanohakusen' through EMS chemical mutationUse EMS as mutagen with different concentration of 0,0.05%,0.1%,0.2%,0.4%? 0.6%respectively to deal with seedlings of‘Iwanohakusen'protospecies with smear method,select superior individuals with few lateral buds,bigger flower diameter and more petals from mutant plants.Experiment results show that 13 superior mutant individuals are obtained through EMS with 5 concentrations,six of which are from 0.05%EMS and seven of which are from 0.1%EMS.The main characteristics of superior mutant individuals are bigger flower diameter and more petals.When concentration of EMS is 0.2%,plant mortality is 48.89%,and no superior mutant individual is found.Therefore,the optima concentration of EMS is 0.1%.Use 13 superior mutant individuals induced from EMS mutation as materials to analyze genetic similarity with protospecies plants through ISSR molecular marker.Experiment results show that 128 strips of protospecies of 'Iwanohakusen' and superior mutant individuals are amplified,and plant genetic similarity coefficient of induced plants of'Iwanohakusen' is between 0.563 and 0.836,when GS is set to be 0.76,14 materials of 'Iwanohakusen' can be divided into 6 sorts.Therefore,there is variation on superior individuals induced from EMS,compared with the protospecies.3.To obtain superior mutant individuals of 'Shenma' through 60Co-y radiation mutationUse "Co-y with different radiation dose(0Gy,10 Gy,20 Gy,30 Gy)to radiate cutting slips of‘Shenma',select superior individuals with few lateral buds from mutant plants.Experiment results show that plants radiated by 60Co-y all have dwarfing mutation,and five superior mutant individuals without lateral buds are obtained,three of which are from radiation dose of 10 Gy,two of which are from radiation dose of 20 Gy,with trait that there is no lateral buds at 15cm below flower disc.Use 5 superior mutant individuals induced from 60Co-? radiation mutation as materials to analyze genetic similarity with protospecies plants through ISSR molecular marker.Experiment results show that 111 strips of protospecies of 'Shenma' and superior mutant individuals are amplified,and plant genetic similarity coefficient of induced plants of 'Shenma' is between 0.622 and 0.811,when GS is set to be 0.794,five materials of'Shenma' can be divided into 6 sorts.Therefore,there is variation on superior individuals induced from 60Co-? radiation mutation,compared with the protospecies.