Study On Comprehensive Evaluation And Propagation Characteristics Of Introduced Landscape Plants In Hohhot

In arid and semi-arid areas,due to the fragile natural ecological environment and limited water resources,and less kinds of landscape plants can be used,so the plant germplasm resources suitable for xeric landscape garden should be further expanded.In this study,the adaptability,ornamental and stress resistance of 78 garden plants were evaluated,and the propagation characteristics and drought resistance evaluation of the selected garden plants were explored.The purpose is to enrich the selection of xeric landscape garden plants,screen propagation methods,enhance its application value,and provide theoretical basis and guidance for landscape greening in arid and semi-arid areas.The main results are as follows:(1)The ecological suitability,ornamental value and stress resistance of 78 kinds of arbor,shrub and herbaceous garden plants were evaluated by Delphi method.According to the comprehensive evaluation,the materials were categorized into four levels.There were17 kinds of excellent landscape plants with the first grade score ≥0.9,and the comprehensive index was the highest.The plants of this level had good adaptability,ornamental and stress resistance,which should be the first choice for the construction of xeric landscape.The second grade score was 0.8-0.9,and there were 32 species in this level.These plants could grow normally in the experimental area with limited flowering and fruiting,or weak resistance to stress.The third level score was 0.7-0.8,and there were 24 kinds of such plants.The adaptability of these plants to the experimental area was general,most of them show slow growth and poor stress resistance in the experimental area.The evaluation score <0.7was grade 4,and there were 5 kinds of such plants,which had low overwintering rate or survival rate.(2)The propagation characteristics of eight plants selected were studied.Morus mongolica,Asparagus gobicu,Allium senescens all belong to light demanding seeds,and the germination rate reached the maximum under light conditions.The seeds of Morus mongolica were light sensitive,and the optimum germination condition was 30℃/20℃continuous light.The seed germination of Asparagus gobicus was affected by the interaction of temperature and light,and under 30℃/20℃ continuous light the germination rate of seeds can reach the maximum.Allium senescens belongs to light promoted germination seeds,15℃and 20℃/10℃ in light condition of were favorable for seed germination.The seeds of Caryopteris mongholica could germinate under all temperature conditions tested,and the germination rate can reach the maximum under 30℃/20℃ continuous dark condition.The germination and dormancy characteristics of dormant seeds of Fraxinus mandshurica,Phellodendron amurense,Rhamnus ussuriensis,Euonymus maackii were studied.The optimum germination condition of Fraxinus mandshurica and Phellodendron amurense seeds was at 20℃ and 20℃/10℃ in the light after 30 days of stratification treatment at 4℃.Seed coat obstacle and endogenous inhibitor were the causes of dormancy of Rhamnus ussuriensis seeds.The seeds were treated with 1mol/L Na OH for 40 minutes or soaked with 40℃ hot water for 20 minutes that could significantly relieve seed dormancy.The treatment of stratification for the seeds of Euonymus maackii could promote the physiological ripening and significantly improve the germination rate,among which the germination rate of stratification treatment for 30 days was 82.7%.(3)The seedling establishment process and physiological changes of Morus mongolica,Caryopteris mongholica,Asparagus gobicus,Allium senescens,Fraxinus mandshurica,Phellodendron amurense,Rhamnus ussuriensis and Euonymus maackii under different soil water conditions were explored to reveal the adaptive strategies of seedlings under water stress.Under different degrees of drought stress,the growth of 8 kinds of plant seedlings was inhibited to a certain extent,but the drought resistance could be improved by regulating the plant growth morphology,protective enzyme system activity and osmotic adjustment substance content,reducing the damage of membrane lipid peroxidation caused by drought stress,maintaining the normal physiological metabolism of plants,thus showing a certain degree of drought resistance potential.In the process of seedling establishment,the results showed that too low or too high field water capacity was not suitable for the growth of plant seedlings,and appropriate soil water conditions could be conducive to the seedling cultivation.The above plants are located in the semi-arid area of Inner Mongolia,with strong resistance and high ornamental value.Therefore,they can be promoted in road landscape and park greening,improve resource utilization efficiency,save maintenance cost,and promote the sustainable development of urban landscaping.(4)The asexual propagation characteristics of Euonymus maackii were studied by tissue culture,grafting and cutting.The stem of Euonymus maackii was used as explant.The best subculture medium was MS + 1.0mg/L 6-BA + 0.1mg/L NAA,and the best rooting medium was 1/2 MS + 3.0mg/L IBA.When the diameter of scion is 0.5-1.0cm,the survival rate is86.36%.The survival rate and rooting rate of the softwood cutting of Euonymus maackii were the highest under the treatment of ABT rooting powder 500mg/L,which were 89% and49%,respectively.For garden plants with development value such as Euonymus maackii,vegetative propagation can accelerate the propagation efficiency more effectively.