The Initial Establishmen Of Tissue Culture System And Adaptive Research Under Dry And Heat Stress For Melinis Nerviglumis Savannah

Ornamental grasses,various in classification,have strong adaptability and unique value of visual enjoyment.They can be widely used in urban and rural landscape ecological construction.In china,ornamental grass,as a landscaping material,is drawing more and more attention.It deservers further and broader study,and is sure to bring a hopeful market.Ornamental grasses have many unique and preferable landscape and ecological features, such as:drought-proof,barrenness-proof,pest-resistance,strong adaptability,and low-cost. Its advantages in the application of landscape gardening are becoming more and more apparent.However,they are not widely popularized because of the following reasons. Majority of Omamental grasses are hard to reproduce and breed;the market prices of finished seedling-products are high;regional climatic conditions differ from place to place.Meanwhile, There are not too many further and complete study on Ornamental grasses,practical application is only limited within a small scale.Therefore,the gardening and ecological value of Ornamental grasses deserves further exploration.Therefore,refining the techniques to breed and cultivate Ornamental grasses is of more and more great significance.Based on systematic comparison of Ornamental grasses' gardening value,taking Melinis Nerviglumis Savannah as experiment material,this experiment aims at primary exploitation of the tissue -cultivating system.This experiment also researches the adaptability to drought and high temperature using man-made imaginary high temperature and dry experimental condition.The following is the result:(1)Selection and disinfection of the tissue in the process of cultivation The selection and disinfection of the tissue in the process of cultivation is a key to the whole process.Trial takes the mature seeds for the material,and its complete disinfection is: immersion in warm water 12～15h→rinse in sterile water twice→75%&20 seconds of alcohol disinfection→rinse in sterile water rinse twice→1%mercuric chloride disinfection 8 minutes→rinse sterile water 6 times→sterile filter paper inoculation.This method assures no infection.(2) The choice of basic medium and hormones for callus induction and differentiation in the process of tissue cultivationCallus induction should select NB as the basic medium.The dark conditions,and the medium components for the NB+BA0.2mg/L +2,4-D6mg/L may assure the highest rate of success,even to 90.6%.Most of the products are embryogenesis callus which have bright color,large size,intense structure,and is dry.MB should be selected as the basic medium for Callus differentiation stage.The light conditions,and the medium components for the MB+NAA 0.5mg/L+BA 1.5mg /L can assure a highest callus differentiation,flourishing and even plant growth.(3) Some important time period in the process of tissue cultivationCallus induction and growth cycle is generally 25 days,induced differentiation 20 days.(4) Rooting and transplanting in the process of tissue cultivationThe process of rooting can be done with the basic medium.A small amount of activated carbon can improve the rooting speed and rooting rate,1/2MB+C0.2g/L brings highest rooting rate,even to 96%.Additional NAA will reduce the speed of rooting,but it speeds up the later root growth.The biggest problem in the process of rooting cultivation is the leaf-yellowing,which is also affecting the survival rate of transplanted seedlings.(5) Growth performance of the Melinis Nerviglumis Savannah under drought and man-made high temperaturethe experiment mainly involves Melinis Nerviglumis Savannah's adaptability under dry and hot circumstances in 10 days.with the time doing on,water content in soil declined in a straight line,while the body-part above the ground dose not show clear negative change,such as wilt,dry up and so on.Plants grow normally.6 days later,some injury begins to be clearer.(6) Melinis Nerviglumis Savannah's physiological changes under man-made dry and hot circumstancesthe experiment mainly involves melinis nerviglumis Savannah's adaptability under dry and hot circumstances in 10 days.with the days doing on,chlorophyll content decreased, while the relative conductivity and MDA,soluble sugar,soluble protein,praline and superoxide dismutase content gradually increased,and peroxides was decreased after the first rising trend.These changes partly indicate the melinis nerviglumis Savannah's adaptability under the dry and hot stress.