EMS Induced Mutation Of Succulents And Effects Of Temperature Factor On The Coloration Of Succulent Leaves

A research on mutation of Pachyveria‘Clavifolia’,Haworthia cymbiformis var.obtusa,Echeveria agavoides‘Red Edge’and Haworthia obtusa OB was carried out.Ethyl methane sulfonate（EMS）was used as the chemical mutagen for treating their peduncle and callus.Many useful mutation types were obtained under the best optimum concentration and immersing time.These mutations can improve the ornamental value of succulents mentioned above and make them diversified.In addition,the environment is one of important factors on enhancement of ornamental value of succulents.Therefore,the leaf coloring of Sedeveria‘Pink Ruby’which can serve as representative for many succulents was studied.The temperature was used as induction factor.The screening of the optimum temperature differential can served as a theoretical and technological guide on the planting and management of succulents.The main results were as follows:1.The optimum tissue culture conditions and the optimal mutagenic condition of succulents were screened:The optimum medium of callus reduction with leaf explants consisted of MS medium plus 4.0 mgl^-11 of 2,4-Dichlorophenoxyacetic acid（2,4-D）and0.35 mgl^-1 of 1-naphtaleneacetic acid（NAA）.Callus reduction rate could reach up to 86%.The best medium of shoot induction was MS medium containing 2.0 mgl^-11 6-benzylaminopurine（6-BA）plus 0.1 mgl^-1v1v NAA.And the shoot induction rate was up to72.9%.The optimum medium of shoot proliferation consisted of MS medium plus 2.0mgl^-11 6-BA and 0.5 mgl^-1v1v NAA.The propagation times reached 3.6 times.The best medium of rapid root multiplication was 1/2 MS medium containing 0.3 mgl^-1v1v NAA and the root inducing was over 89%.Callus was treated with EMS of five concentrations（0,0.05%,0.10%,0.15%,0.20%）and four treatment times（2 h,4 h,6 h,8 h）resulted in0.2%EMS 2 h were Semi Lethal Dose.Taking into consideration of various elements,the optimal Dose was 0.05%EMS for treatment of 2 h.Callus induction rate was 14%and shoot inducing rate from callus was up to 79%.2.The field screening of the mutants of the morphologies of M1 generation were conducted and 11 mutant plants with great potential value from four kind succulent plants were selected.In Pachyveria‘Clavifolia’,3 mutant plants with variations of stalk were found;There was 1 mutant plant which belonged to the variation of plant type in Haworthia cymbiformis var.Obtusa;3 variants were present and their variance is in leaf color in Echeveria agavoides‘Red Edge’;4 mutant plants with variations of leaf color and plant type were found in Haworthia obtusa OB.3.The best temperature differential which made the leaves of Sedeveria‘pink ruby’become red rapidly were screened.The leaf coloring rate increased with the increasing of temperature differential.With illumination for 15 days,the highest rate of leaf coloring（29.9%）was observed under temperature differential of 20℃.With illumination for 30days,not only the highest leaf coloring rate（77%）but also the best color of leaves appeared under temperature differential of 20℃while the effect of leaf coloring was the lowest.Considering together,under temperature differential of 20℃plus illumination for 30 days,the best results of leaf coloring were obtained.