Selection Of Anti-Root Rot Plants Of Medicago Sativa L. Using Toxin Generated By Fusarium Oxysporum

Alfalfa, regarded as "queen of forage", is the most important legume forage in the world. In our country, it is mainly planted in the northern areas, but now in order to expedite the development of the stock raising in southern areas, it has gradually begun to be grown in the South. However, because of the frequent raining and poor permeability of the soil in southern areas, the Root Rot of alfalfa is serious, becoming a primary factor of production decrease. The majority of the pathogenic bacteria of the Root Rot of alfalfa have been accustomed to the soil, and thus it is impossible to effectively control such disease merely by chemical prevention and cure method. The long-term practice has proved that the most efficient and feasible means is to select and cultivate anti-disease varieties. On the basis of reviewing previous experiences of other scholars, the research involved in this thesis tries to devise an innovate method of the anti-disease breeding of alfalfa by using toxin generated by Fusarium oxysporum as reagent, identifying and selecting anti-disease plants when they are young, and select the anti-rot mutant of alfalfa with the association of cell culture technology. The results were proved as following :1, One pathogen of the root rot of alfalfa, preliminarily identified as Fusarium oxysporum, was successfully separated in the experimental field in Southwest University, and a preliminary study on its bringing toxin filtrate biological activeness was conducted. According to the measurement by High Performance Liquid Chromatography (HPLC), the concentration of DON in toxin filtrate was 2.57μg/ml. This toxin filtrate was a Non-Host-Specific Toxin (NHST) for that it could seriously wither the young plants of alfalfa and restrain the growth of radicles of alfalfa, soybean and mung bean.2, Five times-diluted toxin filtrate could significant restrain radicle's growth of ten alfalfa varieties, of which the most sensitive to the toxin were Trifecta and Millennmium, while the most effective anti-disease one was Gannong 2. In the soaking experiment, three times-diluted toxin filtrate's...