Studies On Nematodes In The Rhizosphere Of Cunninghamia Lanceolata

Abstract: Some studies on nematodes in the rhizosphere of Cunninghamia lanceolata have been conducted. Including:(l) Community structure investigation in the rhizosphere of Cunninghamia lanceolata,, carry on the observation of nematode's surrounding environment factor information (including the microbial environment of soil and forest land environment ) and collect at the same time ; (2)The nematodes in the rhizosphere of Cunninghamia lanceolata analysis encloses the dynamic law of vertical distribution and season of the nematode; (3)Nematodes in the rhizosphere of Cunninghamia lanceolata of initial analysis encloses nematode species' characteristic and relation between it and the environmental factors of external world; (4)Nematicidal activity of plant against nematodes in the rhizosphere of Cunninghamia lanceolata were determined and test in this study.l.Rusults of investigation and identification of nematodes in the rhizosphere of Cunninghamia lanceolata showed that there were 11 genera parasitic nematodes (11 species of them), which concluded dorylaimida species, in rhizosphere soil of Cunninghamia lanceolata had been identified, base on the study of mainlymorphological characters of nematodes. Those were Aphelenchus avenae -. Rhadinaphelenchus cocophilus^ Paratrichodorus minor\ Trichodorus primitivus^ Longidorus euonymus -. Xiphinema insigne Loose ■> Helicolylenchus dihystera -. Aphelenchoides saccharic Filenchus cylindricaudatus■. Paratylenchus projectus^ Hoplolaimus spp. and Hemicycliphora spp. The dominant species in two samples are different. Paratylenchus projectus -, Aphelenchoides sacchari -> Filenchus cylindricaudatus and Paratylenchus projectus are dominant species in the sample I. Paratylenchus projectus - Aphelenchus avenae ■. Helicolylenchus dihystera and Xiphinema insigne Loose are dominant species in the sample II.2. Analysis of vertical distribution of nematodes showed that there were different trends on the vertical distribution of varied species in the soil. For example in the sample I Paratylenchus projectus was mainly distributed on the layer of 0-1 Ocm; and the Filenchus cylindricaudatus of 30-40cm has the largest number of population. And {Helicolylenchus dihystera) was mainly distributed on the layer of 20-30cm and 40-50cm; but Xiphinema insigne Loose was on 20-40cm. Species variety in two find in analysing, Sample I species enrich degree are higher than sample II, but its diversified index and value of degree of consistency are counted and lower than sample II. This text make measure analysis to population space distribution pattern of nematode, a series of index China fir nematode assemble degree of different soil layer are used, the soil layer of 0-1 Ocm among them, the gathering degree of nematode's population is the highest, it is the lowest in the soil layer of 500cm is gathered degree.3. Analysis on dynamics of nematodes population in rhizosphere soil of Cunninghamia lanceolata indicated that, except for saprozoic and predatory ones, each species appears distinct but different seasonal fluctuations. There are two maximums (September and April) and two minimums (October and July) in the number of nematode. The population of the nematode happens between January and April with fastest-rising in quantity, the temperature of the period rises slowly, its temperature on average is 14.33°C, the humidity is 79% on average. This kind of climatic conditions helps growth, development and breeds of the plant nematode. It is the cause of fast growth of nematode's population's absolute quantity; Nematode's population's quantity is present the downward trend after April, it is most violent to drop the degree in June - July. Nematode quantity reaches the minimum of the whole year in July with the highest temperatures and the lowest relative humidity minimum. In the period of July-September, because the lasting high temperature is influenced, the whole nematode's population's quantity ranges in low level.4 Dependence analyse of the nematode's Quantity change and the soil physics and chemistry characteristic: Nematode population appearance frequentness and...