Studies On Rapid Propagation And Polyploid Breeding Of Lilium Spp.

Lily is one of perennial bulbous flowers,which belong to the Liliaceae of Lilium.It is one of the famous cut flower of the world and widely used in food and pharmacy industry as well.But due to the low propagation rate of lily bulblet and its susceptivity to virus invasion,the product quality of lily remains very poor.Quick propagation technique can produce large number of plantlets rapidly;polyploid plants by Chromosome doubling induction have such good characteristics like strong plant,thichening scale etc.For these reason,it is widely accepted that studies on rapid propagation and polyploid breeding of lilium spp.is important and significant both in theoretic aspect and in economic aspect.The thesis focus on two main parts,one is the culture medium in rapid propagation of two species,Lilium formosanum×Lilium longiflorum var.scabrum and Lilium Oriental×Lilium Trumpet;The other is polyploid breeding of the same plants.The main conclusions of the studied are listed below:1.In the paper,it reported the results on building the system of regeneration in vitro by different treatments in the culture medium of L.formosanum×L.longiflorum var.seabrum.The result showed:The explants were dipped in the scour 20 minutes and washen 15 minutes by tap water,then sterlized 20 minutes by 0.1%HgCl₂ and 15 minutes by 0.2%NaClO,rinsed 3～5 times by sterilized water in the end.The results indicated that the highest induction frequency(66.7%) and the lowest contaminated frequency(33.3%) was achieved in that treatment.The appropriate medium for inducing lily buds from explants was also MS +1.0mg/L 6-BA+0.1mg/L NAA,induction rate was 100%.The best of multiplocation medium for L. formosanum×L.longiflorum var.scabrum was MS+2.0mg/L 6-BA+0.2mg/L NAA,and multiplication coefficient reached 5.0;the best of multiplication medium for L.Oriental×L.Trumpet was MS+1.0 mg/L 6-BA+0.1 mg/L NAA,multiplication coefficient reached 6.75;the best rooting medium was 1/2MS+ 0.2～0.5 mg/L IBA,the states of plantlets and roots were good,the induction rate and the surviving rate of plantlets are much higer after transplanted to the ground.2.On the base of building the system of regeneration in vitro,the inducing tetraploids of two kinds of Lily was done by the solution of colchicines.The methods were adapted:marinating and composite culture. The result showed:the marinating was a better method.It was treated with colchicines at different concentration and time duration in vitro,and also was treated with admixture of colchicines and 2% Dimethyl Sulfoxide(DMSO).The results indicated that the highest induction frequency(86%) was achieved in the treatment of immersing the shoot tips in colchicines solution at 0.05%for 36h with the 0.2%DMSO;in mixed culture,the highest mutation rate(54%) was achieved when the explants were cultured in a medium containing colchicines at 0.05%for 10d with the 0.2%DMSO.The rate of polyploidy induction by colchicines treatments with DMSO was higher than without it.The induced plantlet was identified by the number of the chromosome.The number of the chromosome was 2n=4x=48,belonging to tetraploids plants.Tetraploid Lily had a good multiplication effect,which cultivated on the best mediums for diploid plant.The optimal medium for rooting was 1/2MS+0.2～0.5 mg/L IBA.The states of multiplication and rooting were good.3.In the paper,it reported the results on the differences of leaf stoma characteristic and exterior configuration,based on the cytological identifications by microscopic watching:Plant morphology and cytology observation on two ploidy of Lily with similar growth stage and environment background suggested that tetraploids were bigger than diploids in the leaf morphology.The thickness and width of the leaves of tetraploids were bigger than the diploids.The thickness of tetraploids were 216.7%and 164.3%of those of the diploids respectively.The length turned shorter and the leaf index became smaller.The length of leaves of tetraploids were 84.8%and 81.3%of those of the diploids respectively;the leaf index of tetraploids were 63.6%and 46.7%of those of the diploids respectively.The number of chloroplasts in the guard cells increased evidently and were 140.1%and 142.6%of those of the diploids respectively.The guard cells(length and width)of the tetraploids obviously augment.:the length and width of tetraploids were 126.9%,143.3%and 158.9%and 142.5%of those of the diploids respectively.The stomas(length and width) of the tetraploids also obviously augment:the length and width of tetraploids were 136.0%, 124.0%and 123.7%,158.5%of those of the diploids respectively.Comparing the characteristic of the tetraploids stomas with that of diploids,the result showed:the density was evidently decrease,were 56.36%and 69.64%of those of the diploids respectively.By the analysis,those indexes were notably different.So leaf thickness,leaf width,stoma density,guard cell size,chloroplast number can be used to identify tetraploid and diploid of lily.4.The tetraploid and diploid plantlets of lily were carried out the low-temperature treatment,then their exosmosis rates of electrolyte and rates of damage of cytomembrane were compared.Under the same temperature,the electrolyte exosmosis rate and damage of cytomembrane of tetraploid plants were lower than the diploid ones.The result indicated that the cold resistance and drought of the tetraploid were both stronger than diploid,it has fully manifested the superiority of polyploidy.Additionally,the mensurate result found that,chlorophyll content was increasing along with the ploidy.This result can provide important data on lily for planting and breeds selectively.