| Dichondra repens is one of the widely-use lawn plant. There is abundant native Dichondra repens in the South-west of China, with great potential of utilization. After the research of 23 Dichondra repens germplasm in the south-western of China on their hereditary constitution and diversity. In view of their abundant variation and genitic diversity, systematic studies on different levels had been made on pop-ecology,morphology,physiological and DNA markers. Comparative study on Dichondra repens germplasm from the extra-morph and resistance with the species as check, for screening the excellent strain and strenthen to reserve or utilize Dichondra repens germplasm. The main research fruits went as follows:(1) In this study area, The native Dichondra repens germplasm were distributed at the altitude of 300m～1970m. The sam of year in collection area was 14℃～18.1℃, annum relative humidity was 63%～81%, climate was the subtropical zone moist monsoon climate, and they could grow in lots of types of soil, such as yellow soil,yellow-red soil,red soil,laterite,purple soil, and so on.. The main characteristic of distribution was lamellar and seldem as accompanying species in community. The ecological environment types could be classified into three types: flood grassland type(field candela, ditch side), mountain hills type(highway, hillside), wood land type(under the woods). The native population showed obvious variation in 10 external morphological characters of Dichondra repens, leave length,leave width,herb hight,leafstalk length,arborization numbers,main stem and the color of leaf and creeping stem had the coefficient of variation were over 20%. analysis of correlation showed that with the increasement of altitude, an area of Dichondra repens leaf got larger (0.37-1.35cm2), leafstalk more thickening (0.47-0.80mm), thickness of leave got more thin (0.189-0.096mm). cluster analysis showed that 23 populations could be classfied into 4 groups based on the results of clustering analysis, large leaf and high stock type; large leaf and short stock type; small leaf and short stock type and small leaf and short stem type. (2) The study on disease resistance of Dichondra repens showed that there were obvious difference between each accession, the amplitude of disease incidence was 0.35%～29.84%, coefficient of differentiation was 1.534; the amplitude of the number of disease spots was 0.77～67.1, coefficient of differentiation was 1.615. according to the incidence and serious extent of each accession, all of the accessions could be divided into 3 grade, among the total, SD200512 had the most serious incidence, was the weak disease resistance accession; SD200407 was the strong disease resistance accession, incidence of other between the two accessions.(3) After an observation on cold resistant of Dichondra repens the results showed different accession had differences in hibemalisation rate, time of dry, time of return green. among which SD200310 from NaXi in SiChuan, SD200406 from DaYi, SD200511 from BiShan in ChongQing, YD200502 from xianFeng in YunNan, GD200501 from DaYang in GuiZhou showed better cold resistance..(4) Genetic diversity of 23 native Dichondra repens accessions from south-western China was tested by Using ISSR Maker, the results showed a total of 138 bands were amplified by 14 ISSR primers, among which 131 bands were found to be polymorphic, the percentage of polymorphic bands reached to 94.9%. And consequently a number of stable DNA fragments were produced, ranging from 6 to 15 per primer, with 9.4 polyrnorphic bands per primer on average. The ISSR-based genetic similarity values among 23 Dichondra repens accessions ranged from 0.211 to 0.871. Abundant genetic diversity among Dichondra repens accessions could be revealed by ISSR marker. Analysis of cluster showed that all the 23 accessions could be distinguished by ISSR markers and divided into 4 groups according to UPGMA method. The results also showed that the genetic diversity in Dichondra repens accessions based on ISSR genetic similarity was correlated with geographic distribution to some degree.(5) According to the difference of ecology environment in collecting areas, all the 23 D. repens accessions could be divided into 5 ecogeography groups, including ChengDu plain group, group for Amb-basin mountain area in SiChuan Province, group for hills in the middle of SiChuan Province, YunNan group, GuiZhou group. After the analysis of genetic polymorphism indexes of each geographical groups of D. repens, the results showed the biggest value of GD was group of Amb-basin mountain area in SiChuan, corresponding with the biggest Shannon index and Simpson index. it indicated that the level of genetic diversity in those accessions were greater than other groups. when it come to each geography group, phenotype diversity on species level Hsp=0.6286, but phenotype diversity on group level Hgroup=0.2807, phenotype diversity on within group and between group were Hwithin=0.4465 and Hbetween=0.5535. So the genetic variation of wild D. repens among geography groups (55.35%) was greater than that within geography groups (44.65%).(6) Dichondra repens blooming in whole of the year except stopping growth in winter. the main blooming date centered on april to June, time of fructification was on July to september. All of the Dichondra repens accessions could be blooming, but there were significant difference in seed-sitting among them. among the SiChuan Dichondr repens accessions of, SD200301,SD200302,SD200303,SD200304,SD200310,SD200311 could be fruited.(7) Studise on seed activity of Dichondra repens accessions from sichuan provence which could be fructification were conducted, and the results showed significant different in seed activity between them. accession SD200301 and SD200302 had the highest value of seed vitality index, and the germination rate could reach over 50% without any treatment which hope to seed produce in the future to base on the study of generative propagation of Dichondra repens. |
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