Effects Of Ozonated Water On Controlling Of Greenhouse Vegetable Disease And Underlying Physiological Mechanism

In recent years,greenhouse vegetable cultivation has not only become the primary cultivation method for increasing crop yields,but also meet the demands for cultivated varieties in off-seasons.However,the growth condition of suitable humidity,warmth and enclosure also results in favorable conditions for the growth of plant diseases and pests.As a strategy for controlling pests,people often use insect nets to protect plants from invasive pests,but these nets do not resist the invasion of plant diseases.Pesticides are widely used to control agricultural diseases and improve crop productivity,but the presence of pesticide residues is of concerning because of the potential impact on human health.Thus,fresh vegetable safety has become a major public concerning.As a strong oxidant,ozone is a well-known,broad-spectrum fungicide.Ozone can rapidly auto-decompose to produce oxygen and leaves no residues in many fields.The aims of this study were to search the moderate concentration ozonated water for infected-pathogen vegetable.In this study,we using ozonated water of different concentrations respectively applied to vegetable pathogen in vitro and the growing vegetables.The results are listed as follows:First of all,research on the effect of ozonated water.The solubility and degradability of ozonated water were affected by temperature,water quality and solvent.The lower pH value of solution concentration of ozonated water is higher.Secondly,in this paper,we used five pathogens of vegetable to research the effect of ozonated water on vegetable pathogen in vitro,containing Erwinia carotovora subsp.carotovora,Ralstonia solanacearum,Rhizoctonia solani,Alternaria solani and Corynespora cassiicola.The results showed that Ecc and Ralstonia solanacearum were completely inactivated with aqueous ozone after the bacteria had been exposed to 0.5 mg/L and 0.8 mg/L ozonated water.Aqueous ozone was directed sprayed to the surface of fungus,fungal growth speed gradually slowly with the ozonated water concentration gradually increase.The growth of fungus was initially inhibited at 4.5 mg/L.When the ozonated water concentration was at 7.5 mg/L,the fungus has no regeneration capacity.The results revealed that the spray ozonated water method is feasible.Thirdly,this research use four common vegetables to research the effect of ozonated water on growing vegetables,containing Brassica campestris ssp.chinensis,Lactuca sativa var.ramose,Cucumis sativus and Lycopersicon esculentum.The growing vegetables were directly sprayed with different concentrations(0,2,4,6,8,10 and 14 mg/L)of dissolved ozonated water in greenhouse.The effects of the treatments on morphology(height,stem diameter,leaf areas)were analyzed,and some treatments were characterized(photosynthetic activity and antioxidant system)by induction of visible symptoms of senescence.The results followed that no negative effects were observed after treatment by spraying ozonated water compared with the control at concentrations below 8 mg/L.However,visible damage to leaf were observed after the plants were exposed to 10 mg/L ozonated water via spraying for 15 days during the plant reproductive stage.Lettuce patience is higher than greens facing the higher concentration ozonated water.However,we observed the leaf withering symptoms caused by 14 mg/L concentration ozonated water and appropriate spay lettuce leaf at concentration at 4-10 mg/L.Cucumber leaf were sprayed at different concentrations of ozonated water,although not cause signs of blade damage,when the ozonated water concentration higher than 10 mg/L,can cause the plant height shorter,female flowers few drops.The appropriate ozonated water concentration for spay lettuce leaf is 6-10 mg/L.Tomato leaf by ozonated water spraying,10 mg/L ozonated water can caused yellowed leaves,the optimal concentration of ozonated water for 4 to 8 mg/L.Fourthly,water and pesticide as control,this research test infected disease vegetables which were sprayed at 4-6 mg/L concentration ozonated water.The results showed that ozonated water can control effect on greens pest and lettuce soft-rot disease,while control effect of 5 mg/L ozonated water was 71.2 %.Therefore,appropriate ozonated water concentration can be used for vegetable pests and diseases control facilities.Fifthly,ozonated water was applied in greenhouse combined with ozone appliance and analysis the effect of ozonated water on the environment.Combing the ozone technology,micro spraying technology,with titanium aeration device,the ozonated water production equipment is featured with high purity and concentration in a large area of greenhouse for crop disease and pests' prevention.The actual application results showed that the ozonated water spraying contents not more than 133.4L/667m2.We used the microbial diversity of high-throughput sequencing platform MisSeq 2 x 300 bp and analyzed the effects of ozonated water on soil microbial community.The results indicated that ozonated water did not change the composition of soil microbial community and the composition of soil microbial important microbial communities no damage compared to the control.In this paper,ozonated water as a means of disease control facilities vegetables on vegetables were analyzed,greens,lettuce,cucumbers and tomatoes with the common pathogenic bacteria and as well as the function of various vegetables in the growth stage.As a powerful antimicrobial substance with potent oxidizing capacity,dissolved ozone may be directly sprayed onto vegetables.This study indicated that 4-6 mg/L concentration of ozonated water directly spraying to the vegetables could affect the crop disease and pest prevention.These results will further help in solving the problem of the safety of vegetables,and establishing the application of ozonated water facilities for vegetables as an alternative to pesticide in the foundation experiment.