Preliminary Establishment Of Rapid Propagation System And Studies On Drought Toleranee Of Rhynchelytrum Repens (Willd.) Hubb

The ornamental grasses had became popular in the European and American countries since 1980s,its popularity has never weakened for over 20 years,they are widespread applicated in planting arrangement in Landscape Architecture and the family gardening at present.Now,the researches toward ornamental grass in domestic are few,and people who know them are not so many.The seeds of Rhynchelytrum repens (Willd.) Hubb were used as explant in this study.We studied on the effect of factors which effect the tissue culture,such as pre-sterilization for explants,calluse induction,adventitious bud induction,rooting and transplanting of reborn young plant,specifically studied the basic medium,hormone type and allocated proportion,preliminary constitued the fast propagation system of Rhynchelytrum repens(Willd.) Hubb.At the same time,we used adult plant of Rhynchelytrum repens(Willd.) Hubb as experimental material,took adult plant of Cynodon dactylon(L.) Pers as comparison,studied physiological change of two kind of adult plants under the same nature drought condition in the artificial climate box,initially summarized drought resistance relations of Rhynchelytrum repens(Willd.) Hubb and Cynodon dactylon(L.) Pers(whose resistance is more strong ),provide certain theory basis for melinis repens's promotion and the application.The main results are as follows:1.Establish the high-frequency regeneration system for Rhynchelytrum repens(Willd.)Hubb(1)The best method for sterilize of explants:it was dip in 75%ethyl alcohol for 30s,then agitating in a solution of 0.1%HgCl₂ for 6min,and finally rinsed five times with sterile distilled water.(2)The medium:the best basic medium for callus induction is MS,and the sutiable growth hormone combination and density is 6-BA0.2mg/L+2,4-D 6mg/L.With hormone combination and density 6-BA 1.5mg/L+NAA0.2mg/L,the bud can grow well and accelerate the multiplication.(3)In subculture,the more of the subculture time,the higher of coefficient of multipalcation.The coefficient increased rapidly in two generation,then the coefficient increased more like before or decreased after two generation.(4)The best medium for rooting is 1/2MS+NAA0.5 mg/L.The quality of the root system was better than others,and the rooting rate is 100%.The survive ratio could reach 94.4%when they are transplant to the medium composed with one part crushed soil and two part Humus soil. 2.The drought resistance comparison of Rhynchelytrum repens(Willd.) Hubb and Cynodon dactylon(L.) Pers toward drought stress(1)During subsequent drought stress,the SRWC(soil relative water content) of Rhynchelytrum repens(Willd.) Hubb decresed more remarkably than that of Cynodon dactylon(L.) Pers.Both of the leaves'Plasma membrane Permeability of two kind of plants increased.And the trend escalate with the prolong period of drought stress,The rising speed of Plasma membrane Permeability's in Rhynchelytrum repens(Willd.) Hubb is more quickly than in Cynodon dactylon(L.) Pers.(2)During drought stress,the rise rule of proline content in the leaves of two kind of plants is not too obvious,The increases proportion of proline content in Rhynchelytrum repens(Willd.) Hubb is higher than in Cynodon dactylon(L.) Pers,The soluble sugar content in two kind of plants' leaves had the change tendency of rise gradually,the soluble sugar content increased more or less,soluble sugar's quantity which accumulated in Rhynchelytrum repens(Willd.) Hubb was lower than in Cynodon dactylon(L.) Pers in the end,(3)During subsequent drought stress,the content of Chlorophyll in both of two plants showed a slight increase in the early phase of drought and then a decrease with further increase in magnitude of water stress.The time at which Chlorophyll content in Rhynchelytrum repens(Willd.) Hubb' leaves start to drop was earlier than in Cynodon dactylon(L.) Pers.(4)Malondialdehyde(MDA) content in leaves of two kind of plants rised first,then dropped,and rised in the end.During the whole drought stress,the MDA content in leaves ofRhynchelytrum repens(Willd.) Hubb was higher than in Cynodon daetylon(L) Pers,and the former rised more remarkably than the latter.(5)During drought stress,soluble protein content in leaves of both Rhynchelytrum repens(Willd.) Hubb and Cynodon dactylon(L) Pers rised slightly and then reduced,but the overall change scope is not too obvious.The drop proportion of protein content in Rhynehelytrum repens(Willd.) Hubb was higher than in the Cynodon dactylon(L) Pers.The activities of Superoxide Dismutase(SOD),peroxidase(POD) and Catalase(CAT) of leaves in both Rhynehelytrum repens(Willd.) Hubb and Cynodon daetylon(L) Pers showed an increase in the early phase of drought and then a decrease with further increase in magnitude of water stress,those changes occurred in Rhynchelytrum repens(Willd.) Hubb prior to those in Cynodon dactylon(L) Pers.(6)Summarise above we concluded that Rhynchelytrum repens(Willd.) Hubb has worse drought tolerance ability than Cynodon dactylon(L) Pers.