| Soil fumigation is used to control soil fungi, bacteria, nematodes, weeds and pests for solving the replanted problem of highly added value crops. Methyl bromide is a good soil fumigation agent in the world that can control all kinds of soil spread diseases, but it is also an ozone-depleting substance (ODS) and going to be phased out in 2015. So, to select substitute and alternative technology has become the hot issues all over the world. This study evaluated the chemical substitutes 1,3-Dichloropropene and non-chemical substitute marigold on the effect of root-knot nematodes and microbial community. Research under laboratory conditions shows that the LC50 of cis-1,3-D, trans-1,3-D and 1,3-D on the root-knot nematodes was 1.98 mg/kg,2.76 mg/kg and 2.12 mg/kg, respectively. Field trials revealed that the effect of cis-1,3-D, trans-1,3-D and 1,3-D on nematodes in the plough layer was more than 90% by applied to the field at 100.00 to 200.00 kg a.i./hm2.After 1,3-D, cis-1,3-D and trans-1,3-D fumigation, Microbial community structures were evaluated with BIOLOG Eco-plates. Compared with untreated control, bacterial community structure was not changed after cis-1,3-D and 1,3-D fumigation, but altered after trans-1,3-D fumigation.Safety results show that 1,3-D at the doses of 100mg/kg,50 mg/kg,25 mg/kg,12.5 mg/kg and 6.25 mg/kg had effectively controlled nematodes after 5 days'fumigation. After 7days of opening greenhouse, there was no phytotoxicity risk to tomatoes and cucumbers.The population dynamics of Meloidogyne incognita was systematically studied. The increase of M. incognita in soil was related to the development of cucumber, nematodes reproductive cycle and the temperature of the soil. After transplanting cucumber, M. incognita infecting incognita had three obviously high peak time, i.e. on the 15,31 and 45 days, respectively. The results showed that 1,3-D could effectively reduce the J2 population in the soil, also reduce seedling disease rate and galling index. So the key time of controlling the root-knot nematode disease was before seeding. It was effectively reduced the number of J2 population and protected the main roots of crops that the soil be treated with nematocide before sowing.It was significantly reduced the number of M. incognita comparing with untreated control that African marigold and cucumber rotated in the field, the M. incognita population reduced 85% after planting African marigold one week later, and could retained to a low level. After being transplanted cucumber, J2 population of M. incognita was higher than that of 1,3-D and methyl bromide plots in the early period of the growth process, with no apparent growth trend. Although the root was infected, the growth of cucumber was still promoted and it's yield was increased, but it's effect was lower than that of 1,3-D and methyl bromide treated.The active component extracted from African marigold on M. incognita J2 was studied. The experimental results showed that African marigold contained light active component. The effect on nematodes was significantly higher in the light condition than that in the absence of light. The content of a-terthenyl in the extracts was investigated by HPLC, and results showed that the phototoxicity of the extracts was generally the alpha-terthienyl contained in them. The above results showed that 1,3-D could be used as alternatives to methyl bromide for controlling the disease of nematodes. Marigold could reduce the population of nematodes, which could control nematodes and increase the yield, but the effect was lower than that of 1,3-D and methyl bromide treated. |
PDF Full Text Request