Impact Of Alternative Technologies To The Use Of Methyl Bromide On The Tomato Root-knot Nematodes (Meloidogyne Spp.) And Soil Free-living Nematode Populations Dynamic

Four alternative technologies to the use of methyl bromide (MB) in soil fumigation - resistant rootstock, metham sodium(MS), dosage reduction of MB and MS by virtually impermeable films(VIF) cover, soil solarization combined with selected biological control agents (SS+BCA) - were chosen for application to an experimental site in Qingzhou (Shandong Province, China)from Jul.2002 to Jul.2003. The treatments were: SS+BCA,MB,MB+VIF,MS and MS+VIF .Maofen and Grafted maofen tomato were planted equally in each plot referring to different treatment. The total number of root-knot nematodes (Meloidogyne spp.) and galling index, the free-living nematode populations, microbial biomass were investigated respectively. The results are as follows: 1 . Nematodes were identified mainly into five orders:Rhabditida,Tylenchida,Dorylaimida,Tylenchida,Monhysterida. Furthermore they were distinguished into four trophic groups: bacterivores,fungivores, plant parasites, omnivores/predators.2. The density of second stage juvenile of root-knot nematodes (J2 ) reached the highest level in May or June. The result of surveying the galling index show that the resistant rootstock can effectively control the root-knot nematodes( the average index is 45.6 in Maofen and 4.5 in grafted Maofen),So did the soil fumigation, however, less effectively comparatively. The index of SS+BCA plot was highest of all five treatments and reach 65.8 (maofen)and 7.1 (grafted maofen).The correlation coefficient of nematode proportion between J2 and Rhabditida,Tylenchida,Dorylaimida nematodes were-0.87, -0.52, -0.61(Maofen),-0.79,-0.56,-0.61(Grafted maofen).3. The resistant rootstock can decrease the density of fungivorous and plant parasitic nematode populations. The density of fungivorous and plant parasitic nematode populations in Grafted tomato plots were 3.9 and 128.9 individual/1 00ml soil , which were 8.0 and 183.4 individual/1 00ml soil in maofen plots. Soil fumigation can decrease the density of plant parasitic nematode populations and the four chemical fumigation were not significantly different in between, and were significantly different from the SS+BCA treatment.4. The rootstock can increase the richness of nematode community and decrease its evenness . The nematode community richness index and evenness index in Grafted maofen plots were 0.55 and 0.73,which were 0.51 and 0.76 in maofen plots. The soil fumigation can increase the richness and evenness of nematode community.5. The nematode community PPI/MI(plant parasite index/maturity index) value were 2.74 in Graftedmaofen plots, which were 11.5 in maofen plots. Soil fumigation can decrease the PPI/M1 value of nematodes community and there is no significant difference In between.6. The soil microbial biomass carbon reached the lowest level in oct.2002 and jun.2003. The soil fumigation can decrease the microbial biomass carbon and accelerate its circulation.