Research On Mechanism Of Wedelia Trilobata (L) Hitch Invased Hainan Island

Wedelia trilobata(L.) Hitchc is a perennial rhizomatic plant native to South America and Central America; it was introduced into China as ornamental plant in 1970's, and has become one of the detrimental weeeds in region of South China and other seaside, the invasion of Wedelia trilobata(L.) Hitchc has caused severe impacts on native biodiversity of these places. The purpose of the present study is to investigate the mechanisms underling its successful invasion ,and try to find some effective ways for its control.This work included the following three aspects:1. Research the infection and evaluation of vegetable diversity on Hainan Island caused by invasion of Wedelia trilobata (L.) Hitchc, the results showed that the invasion of Wedelia trilobata (L.) Hitchc had a large effects on species composing and vegetable diversity of plant community on Hainan Island. Wedelia trilobata (L.) Hitchc invaded more severely, the species was lower, the vegetable diversity of the plant community was smaller.2. We compared internode length , branching intensity, branching angle, frequency distribution of internode length, frequency distribution of spacer length,ramet population density and ramet height of Wedelia trilobata (L.) Hitchc among two habitas including the wild and indoor.The result reveal that characters of Wedelia trilobata (L.) Hitchc such as spacer length and branching angle differed among habitats,while branching intensity did not. Wedelia trilobata (L.) Hitchc expresses highly adaptive and plastic ecological strategy to enviroment.3. By using inter-simple sequence repeat (ISSR) makers,this paper studied the gentic variation of Wedelia trilobata (L.) Hitchc from 480 accessions,and genetic structure between the 8 populations.The main results were follows:(l).A total of 5 ISSR primers were employed on 480 individuals of Wedelia trilobata (L.) Hitchc from 59 primers, and 66 scorable amplified polymorphic were detected, of which 65 (PPL 98.48%) were polymorphic loci. Genetic diversity analysis showed that Nei's gene diversity(He)was 0.2188 and Shannon's genetic diversity index(I)was 0.3504 in species. Wedelia trilobata (L.) Hitchc had a high level of genetic diversity. The total genetic diversity (Gst) was 0.4095. Genetic differentiation mainly occurred within populations (59.02%), and without populations (40.98%). The potential of invasion and distribution are extremely strong. These characteristics made it spread rapidly and multiplyIn order to control its further spread, we should intensify efforts. Besides the introduction of foreign advanced technologics, we should study the chemical and biological control methods which will suit for China.