Study On Cutting Propagation Technology And Seedling Shade Resistance Of Melastoma Dodecandrum

Melastoma dodecandrum is an evergreen subshrub of Melastoma in Melastomataceae.It has rich leaf color,purple flowers,black edible fruit,and the ground can be used as medicine,which has strong application value.In this study,the cutting propagation technology and shade tolerance mechanism of M.dodecandrum were discussed.Cutting experiments were conducted to explore the effects of different rooting agents,different cutting substrates and different cutting seasons on the rooting effect of M.dodecandrum cuttings.Shading experiment The two-month-old cutting seedlings of M.dodecandrum were used as materials to explore the changes in growth morphology,physiological and biochemical characteristics and anatomical structure under CK（full light treatment）,1C（50%shading treatment）,2C（70%shading treatment）and 3C（85%shading treatment）.The membership function analysis method was used to comprehensively evaluate the stress resistance of M.dodecandrum under different shading treatments,It can provide a theoretical basis for the popularization and application of wild plant M.dodecandrum in gardens in the future.The test results are as follows:（1）The results of exogenous hormone orthogonal test showed that the rooting types of M.dodecandrum included three types:knot rooting type,bark rooting type and mixed rooting type,which belonged to shrubs that were easier to root.The effects of different hormone treatments on rooting showed that the most suitable treatments for rooting were A₂B₃C₁(500 mg·L^-1NAA treatment for 0.5 min)and A₃B₁C₃(100 mg·L^-1IBA treatment for30 min).Different cutting matrix experiments showed that the mixed matrix of garden soil/vermiculite/perlite（1:1:1）was the best matrix for cutting rooting of M.dodecandrum.However,considering the operability of promoting the production of"Melastoma dodecandrum roll",a single garden soil is more suitable for slope protection plants.The experiment of different cutting seasons showed that the rooting effect was the best in March,and the rooting rate could reach 96.67%;Phenophase observation showed that M.dodecandrum had evergreen leaves in Jiangxi,and the flowering time was concentrated from May to July.（2）The results of shading test show that the plant height,leaf length,leaf width,leaf area,leaf fresh weight,water content and specific leaf area of M.dodecandrum seedlings increase with the degree of shading,while the number of leaves per plant decreased.A series of root growth indexes such as the longest root length,total root length,total root surface area,total root volume and total root tip number increased first and then decreased with the increase of shading degree,and reached the maximum at 2C.Stem and leaf biomass,shoot dry weight,and total biomass were also maximum under 2C treatment.The contents of total N,total P and total K in the leaves of M.dodecandrum seedlings under shading were higher than those under full light.（3）M.dodecandrum belongs to heterophyllous,single-layer palisade tissue.With the increase of shading degree,the thickness of leaves,palisade tissue,spongy tissue,and lower epidermis thickness all thinning.The upper epidermal thickness of CK was significantly greater than that of shading treatment.With the increase of shading degree,the main vein thickness and the ratio of grid to sea decreased first and then increased,and the maximum was under CK treatment.（4）The initial fluorescence（Fo）,maximum fluorescence（Fm）and variable fluorescence（Fv）were the highest in 3C,and significantly higher than other treatments;the maximum photochemical efficiency（F_v/F_m）was the highest in 3C,and there were significant differences between 2C,3C and CK.The actual photochemical efficiency（Y（II））was the highest in 2C,and the shading treatment was significantly greater than the full light.There was no significant difference between photochemical quenching coefficient（q P）and non-photochemical quenching coefficient（q N）.It can be seen that shading can improve the photochemical efficiency of M.dodecandrum seedlings.（5）The contents of chlorophyll a,chlorophyll b,total chlorophyll and carotenoid in the leaves of M.dodecandrum seedlings increased with the increase of shading intensity,while the contents of anthocyanin and chlorophyll a/b decreased.The relative conductivity of CK and 3C was significantly higher than that of 1C and 2C.The MDA content of CK was significantly higher than that in the other treatments.SOD and CAT activity were the strongest in CK,significantly higher than those observed in 2C and 3C;The contents of SS,SP and total flavonoids were the highest in CK and the lowest in 3C,and there were significant differences among the treatments.The results showed that CK and 3C were not conducive to M.dodecandrum growth,while 1C and 2C were conducive to M.dodecandrum growth.（6）The results of shading test show that M.dodecandrum has good negative resistance,using appropriate shade treatment can promote its growth.According to the comprehensive evaluation of membership function value analysis method,the resistance of M.dodecandrum seedlings under different shading treatments was as follows:2C（70%shading treatment）>1C（50%shading treatment）>3C（85%shading treatment）>CK（full light treatment）.Comprehensive analysis showed that M.dodecandrum seedlings grew best under 70%shading treatment.