Studies On Nematodes In The Rhizosphere Of Schima Superba

Forestry nematode is an important kind of pathogen of forestry, with broad distribution characteristics, and can result in serious plant diseases through getting nourishment from the host, or infecting host together with fungi or bacteria. And some species of plant nematodes can transmit viruses. Schima superba is an important type of culture wood, with many excellent attributes, and can defend against forestry fire efficiently in south China. But throughout preliminary investigation, we had discovered that there were some species of nematodes in rhizosphere soil of Schima superba, and the totle number of population was large. But studies on this research and the relative research have not been reported at home and abroad. Thus, some studies on nematodes in the rhizosphere of Schima superba had been conducted on this research. Results based on studies are as follows:1. Results of investigation and identification of nematodes in rhizosphere soil of Schima superba showed that there were 12 genera parasitic nematodes (13 species of them), which concluded dorylaimida species, in rhizosphere soil of Schima superba had been identified, based on the study of mainly morphological characters of nematodes. Those were Hemicriconemoides ghaffari, Paratylenchus projectus, Tilenchus cylindricaudalus, Aphelenchoides sacchari, Helicotylenchus dihystera, Helicotylenchus digonicits, Xiphinema hunaniense, Longidorus euonymus , Macroposthonia xenoplax , Trichodorus christiei , Paratrichodorus minor , Rhadinaphelenchus cocophilus and Aphelenchus avenae. Among them, Hemicriconemoides ghqffari, Paratylenchus projectus, Tilenchus cylindricaudatus , Aphelenchoides sacchari were predominant species, and their totle population were 93.47% of the totle population of all parasitic species in rhizosphere soil of Schima superba. Because of the large population of the predominant species, they may endanger the health of host if their totle population gets further enlargement, then, plant disease may occur. Therefore, the further research of their biology and their underlying destruction to their host is necessary, and effective measures should be taken to prevent plant diseases. But for other species, due to their small population, they may not result in serious diseases in normal cases. The results also showed that parasitic and dorylaimida nematodes were 66.61% of the totle population, but saprophytic and sarcophagous species wereonly 33.39%.Reseach also indicated that most population of nematodes were distributed on the investigated area behind Fujing forestry college, and only one species: Xiphinema hunanieme was mainly found on the area of ZhangZhou, but population on the area of Jinou was very scarce.2. Analysis of vertical distribution of nematodes showed that there were different trends on the vertical distribution of varied species in the soil. Hemicriconemoides ghaffari was mainly distributed on the layer of 30~60cm; and the one of 30~40cm has the largest number of population. And paratylenchus projectus was mainly distributed on the layer of 0~10cm; but Tilenchus cylindricaudatus was on 20~40cm and Aphelenchoides sacchari on 20~30cm. But all in all, nematodes in rhizosphere soil ofSchima superba mainly gathered on the layer of 0~10cm and 20~40cm, on which the totle population was in 70%. And saprozoic and predatory species mainly gathered on the first layer, and their population was decline with the increase of depth. But most parasitic ones were on the layer of 0~ 10cm and 30~40cm.3. Analysis on dynamics of nematodes population in rhizosphere soil of Schima superba indicated that, except for saprozoic and predatory ones, each species appears distinct but different seasonal fluctuations. The largest number of Hemicriconemoides ghaffari appeared in March of 2003: And paratylenchus projectus flourished in three periodes: September of 2002 ^ November of 2002 and April of 2003. And Tilenchus cylindricaudatus flourished in August of 2002 and April of 2003; but Aphelenchoides sacchari in September of...