Study On Cold Resistance And Rapid Propagation Of Introduced Hosta Species

Hosta is a kind of perennial and shade-tolerant herb belonged to lily family and have a great ornamental value for city virescence.Taking the introduced Hosta 'Gold Standard', Hosta 'Grand Tiara',Hosta'Middle Ridge',Hosta plantaginea and Hosta clausa var.ensata as the experimental materials,the variational characteris of several physiologic factors such as the velum-penetrating property and the contents of the dissoluble sugar and albumen,dissociative praline and malondialdehyde(MDA) were measured.Combing the restored status of hosta growth after lower-temperature stress,the cold resistance of several hostas were evaluated.In addition,the growth process and tissue culture of hostas were also studied.The results can provide an important theoretical support for the application and species preservation of hostas in Harbin.The main results were as follows:(1) All five hostas could healthily grow in Harbin and showed several excellent ornamental characteristics.For example,Hosta 'Grand Tiara' exhibited high stability of flower and leaves.(2) Under two kinds of lower-temperature treatement,the electrolyte osmotic rate of hostas root increased with the increase of the degree and time of temperature decrease.By utilizing the equations of temperature and conductance,the semilethal temperatures of Hosta 'Gold Standard',Hosta 'Grand Tiara',Hosta'Middle Ridge',Hosta plantaginea and Hosta clausa var.ensata were -22.65,-23.14,-20.47,-27.71,and -25.78℃,respectively.(3) During the lower-temperature treatment,the contents of the dissoluble sugar,dissoble albumen,and MDA in hosta roots showed a variation trend of increase first and then decrease with the increase of the degree and time of temperature decrease.However,the variation rangs were different for different hostas.The whole trend for the content of dissociative praline was continuously increased,but there was no significant relationship between the content of dissociative praline and the treated temperature and time.(4) The survie rate of restored growth for five hostas after lower-temperature treatment dcreased with the increase of the degree and time of temperature decrease.The result indicated that the order of cold resistance for five hostas was in turn Hosta clausa var.ensata, Hosta'Middle Ridge',Hosta 'Gold Standard',Hosta 'Grand Tiara' and Hosta plantaginea.(5) The callus inducement rates were different for different part of explants of Hosta.For bud,upper part of stem,pedicel and ovary,the inducement was higher,and which can be taken as the first materials of tissue culture.The best medium for bud,stem and pedicel of Hosta 'Grand Tiara' tissue culture was MS+6-BA 4.0mg/L+NAA 0.2mg/L,for the ovary of Hosta 'Grand Tiara',was MS+6-BA 3.0mg/L+NAA0.2 mg/L,and for the root of Hosta 'Grand Tiara',was 1/2 MS+1 g/L active carbon.