| Lanzhou lily(Lilium davidii var.Unicolor)is a famous local vegetable in Gansu.It is also the only sweet lily in China.It is only suitable for planting in the Eryin mountainous area around Lanzhou in central Gansu.At the same time,its distribution area is narrow,asexual reproduction,perennial cultivation,continuous cropping phenomenon is very common,and continuous cropping obstacles are very serious.In order to study the application of high-efficiency,low-toxicity,green,and safe soil continuous cropping obstacle treatment technology,this study used soil fumigation combined with microbial inoculants to regulate soil microbial flora to overcome soil continuous cropping.Obstacles as a basic idea,in 2018-2019,a two-year two-point experimental study was designed,a total of 4 treatments: control(CK),soil fumigation using metham sodium(SFM),microorganism fertilizer treatment(MF),a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer(SFM + MF);through measuring several lily plant growth indexes and physiological indexes,soil microbial indexes and soil chemical and physical properties indexes,the effects of soil fumigation and microbial inoculum combination on alleviating the continuous cropping obstacles of Lanzhou lily were evaluated And its physiological and biological mechanism.The main research results are as follows:1.The effect of different soil treatments on the plant height and stem thickness of Lanzhou lily in each growth period is not significantly different from that of CK treatment,but the dry fresh weight,root vitality and lily yield of the above and below ground of the lily plant are determined.The results show that SFM(soil fumigation using metham sodium)treatment inhibits the growth of lily plants to a certain extent and reduces the yield of lilies.MF(microbial inoculant treatment)treatment promotes the growth of lily plants and increases the yield of lily of Lanzhou.SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)treatment can reduce the yield reduction effect of SFM(soil fumigation using metham sodium)treatment.MF(microbial inoculant treatment)treatment also has the effect of continuously and significantly increasing the yield of lily in Lanzhou;the adverse effect of SFM(soil fumigation using metham sodium)treatment on the growth of lily is a long-term negative effect.Continued addition of microbial inoculant to pesticide-contaminated fields can Significantly reduce the negative effects brought by the use of metham sodium.2.Different soil treatments have a significant effect on the number of soil microorganisms in the continuous cropping lily.Among the four treatments,the MF(microbial inoculant treatment)treatment optimizes the soil biochemical environment and promotes the process of the continuous cropping lily soil changing from fungal type to bacterial type.SFM(soil fumigation using metham sodium)and SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)treatment effect is second.MF(microbial inoculant treatment)treatment reduces the number of soil fungi to a certain extent,and effectively increases the number of soil bacteria and actinomycetes.SFM(soil fumigation using metham sodium)treatment has the effect of permanently reducing the number of soil fungi;but it has no significant effect on the number of bacteria and actinomycetes;in the plot S1,the number of fungi in the seedling stage of SFM(soil fumigation using metham sodium)treatment is reduced by 68.92% compared with CK;The number of fungi at the seedling stage treated by MF(microbial inoculant treatment)increased significantly by 239.38% compared to CK;the number of actinomycetes at seedling stage increased by 133.97% compared to CK;SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)treatment number of fungi at the seedling stage decreased by 62.80% compared to CK;the number of bacteria at the seedling stage increased significantly by 113.67% compared to CK.In plot S2,SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)treatment had little effect on the number of fungi and actinomycetes,but it effectively increased the number of bacteria.SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)treatment at the harvest stage,the number of fungi was significantly reduced by 57.00% than CK;SFM(soil fumigation using metham sodium)treatment at the flowering stage,the number of fungi was 67.02% lower than CK;The number of actinomycetes at the seedling stage after treatment was significantly lower than that of CK treatment by 23.08%.The number of fungi in the harvest period of MF(microbial inoculant treatment)treatment was significantly reduced by 36.14% than that of CK;the number of bacteria in the seedling stage of MF(microbial inoculant treatment)treatment was significantly increased by 89.44% compared with CK;the release of MF(microbial inoculant treatment)treatment during harvest The number of bacteria increased by 178.14% compared with CK.Compared with SFM(soil fumigation using metham sodium)treatment,SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)treatment during the flowering period,the number of bacteria increased significantly by 287.38% compared with CK treatment,and the number of actinomycetes during harvest was significantly higher than CK treatment 321.42%.3.Different soil treatments have a significant effect on the soil physicochemical properties of continuous cropping lily.Among the four treatments,MF(microbial inoculant treatment)treatment lowered soil pH,increased soil total porosity,improved soil water holding capacity,and reduced soil bulk density,Improve the soil physical structure,significantly improve the soil nutritional status,increase the available nutrient content in the soil,optimize the plant growth environment.Compared with SFM(soil fumigation using metham sodium)treatment,after SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)treatment,its total porosity and water content have increased,and all its physical and chemical indicators have reached or exceeded CK level.In plot S1,the EC value,water content,and total porosity of MF(microbial inoculant treatment)treatment were significantly increased by 16.10%,12.50%,and 35.92%,respectively,and the soil pH and bulk density were significantly reduced by 5.07 and 2.70 than CK.%;MF(microbial inoculant treatment)treatment of alkali-decomposed nitrogen,organic matter,available potassium,available phosphorus content increased significantly by 154.95%,8.53%,15.85%,292.74% compared with CK;in the four groups of observations in plot S1,There are 2 groups of SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)significantly higher than the corresponding SFM(soil fumigation using metham sodium)treatment observations,there is 1 group SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)significantly lower than the corresponding SFM(soil fumigation using metham sodium)treatment observations,the difference between the 1 group is not significant.In plot S2,compared with CK treatment,the EC value of MF(microbial inoculant treatment)treatment was significantly increased by 16.67%,pH and soil bulk density were significantly lower than that of CK treatment;MF(microbial inoculant treatment)treatment of alkaline nitrogen,The contents of organic matter,available potassium and available phosphorus were significantly increased by 95.41%,8.01%,7.75%,476.80% compared with CK;the available phosphorus content of SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)treatment was significantly increased by 195.88 than CK %.Among the 4 observations of S2 in the plot,3 groups of SFM + MF(a combination of soil fumigation using metham sodium SFM and Microorganism fertilizer)were significantly higher than the corresponding observations of SFM(soil fumigation using metham sodium),and the difference of 1 group was not significant.To sum up,the combination soil fumigation using metham sodium and microorganism fertilizer could not alleviate the obstacles of Lanzhou lily continuous cropping,on the contrary,metham sodium fumigation is likely to cause chemical damage to lily.However,microbial fertilizer can enhance the plant growth and increase its yield,thus it alleviates the obstacles of continuous cropping.Moreover,it can reduce the negative effects of metham sodium fumigation treatment effectively in spring.The results also demonstrated that the microbial fertilizer,which prevents the replanting soil change from bacterial type to fungal type soil,optimizes the soil physical structure,and improves the soil nutrient level,plays important roles in alleviating the continuous cropping.At the same time,this is also an important biological mechanism for its reduction of metham sodium fumigation.In totally,due to the lower temperature and lower soil water content in spring in the cold and arid climatic area in northwest China,Methyl isothiocyanate(MITC)and its precursors metham sodium and cotton vinegar,which might not decompose and volatile completely and be prone to make some chemical damage the crops,should be cautious to be used to fumigate soil in vegetables culture conditions where the crops are sowed in spring without irrigation in this area. |
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