Application Of Bacillus Spp. AMCC100153 Against Root-knot Nematodes Of Tomato

The root-knot nematodes(Meloidogyne spp.)are sedentary endoparasites and are among the most damaging agricultural pests attacking a wide range of crops.The traditional method of nematode control is based mainly on chemical nematicides.However,the potential negative impact on environment and ineffectiveness after prolonged use have led to a total ban or restricted use of most chemical nematicides and an urgent need for safe and more effective alternatives.Application of microorganisms antagonistic to root-knot nematodes or compounds produced by these microbes could provide an additional option for managing the damage caused by root-knot nematodes.In the in vitro test,a bacterial strain Bacillus spp.AMCC100153 showed a strong ability to inhibit the root-knot nematodes.Further studies based on pot experiments including the biocontrol effects of Bacillus spp.AMCC100153 on root-knot nematodes,influence on tomato growth,real time PCR detection of the number of Bacillus spp.were all discussed in this paper,and the main results were as follows:(1)Experiments on isolation,purification and enrichment of pathogenic root-knot nematodes.For the greenhouse biocontrol experiments,pure populations of a root-knot nematode species(identified molecularly as Meloidogyne incognita)collected from the site of the experimental field,were used.A single egg mass was successively multiplied on tomato in pots for 5 more tests.The results indicated that the obtained root-knot nematodes could grievously cause damage to tomato and be used for the next experiments in future.(2)The nematocidal activity of Bacillus spp.AMCC100153.In the in vitro test,we obtained a bacterial strain Bacillus spp.AMCC100153.As comparison with controls,the mortality of J2 of root-knot nematodes reached to 95% and the egg hatching rate decreased to 0% after treated with the 48 h fermented supernatant fluid for 24 h.The compounds with the antagonistic activity were resistant to some extent against temperature,pH.(3)The pot experiments revealed that Bacillus spp.AMCC100153 could significantly reduce root-knot nematode densities compared with control and the controlling efficiencies reached above 70%.The current study indicated that the pre-planting application of Bacillus spp.AMCC100153 could significantly reduce soil J2 density,egg production and root galling.Meanwhile,Bacillus spp.AMCC100153 showed the promotion effects on the tomato growth.(4)In the field experiments,Compared to the control,Bacillus spp.AMCC100153,reducing the M.incognita J2 densities by 68.46%(15d)and 74.27%(120d),and the controlling efficiencies reached 77.31%(150d).Be similar with the pot experiments,Bacillus spp.AMCC100153 could promote the tomato growth,and increase the tomato yield about 10% in 120 d after planted.(5)The colonization experiments showed that Bacillus spp.AMCC100153 could be colonized steadily in tomato rhizosphere.In the pot experiments,after inoculated 60 d,the amount of the strain still kept 2.54×106CFU/g soil;In field experiments,the amount of the strain still kept 1.19×105CFU/g soil and 8.14×103CFU/g soil after inoculated 90 d and 120 d.