Effects Of Typical Pesticides On Soil Quality And Tomato Growth In Greenhouse Vegetable Field

Effects and toxicological mechanism of the complexes residue of two pesticides on soil quality andfacilities vegetables was still remaining a puzzle in greenhouse vegetable production. This studyinvestigated the effects of soil quality and tomato growth under the single or complexes application ofinsecticide imidacloprid (B) and fungicide carbendazim (D) from seed germination, seedling growth,physiological and biochemical index at the individual level, transmission electron microscope at thecellular level and PCR-DGGE at the molecular level by employing the tomato variety of Zhongza No.9and106which were widely cultivated in Shouguang, Shandong province as the indicator plants. Themain results were as follows:1. The application of pesticides within0-0.07mg·L^-1of imidacloprid and0-0.4mg·L^-1ofcarbendazim in single use promoted seeds germination and the growth of roots and shoots. Whenimidacloprid concentrations exceeded0.07mg·L^-1and carbendazim concentration exceeded0.4mg·L^-1,there were inhibitory effects on the growth of tomato seeds, and the effects were more obvious when theconcentrations were higher.2. No matter single use or their combinations, the application of pesticides within0-0.07mg·L^-1ofimidacloprid and0-0.4mg·L^-1of carbendazim promoted the plant fresh weight and chlorophyll contentof the two kinds of tomato. When imidacloprid concentrations exceeded0.14mg·L^-1and carbendazimconcentration exceeded0.8mg·L^-1, there were inhibitory effects on the addition of plant fresh weightand chlorophyll content, and the inhibitory effects exacerbated with the increase of pesticidesconcentration. No matter single use or their combinations, the contents of free praline as well as PODand CAT were increased in varying degrees. It indicated that the effect of pesticides application on thegrowth of tomato was a kind of adversity stress.3. The application of pesticides within0-0.07mg·L^-1imidacloprid and0-0.4mg·L^-1carbendazim insingle use led to phenolic compounds accumulate in the tomato cells, and the application of bothimidacloprid and carbendazim led to some unknown substances in the tomato cells, which weresupposed as resistance materials due to the stress of the pesticides. The complexes application of2.8mg·L^-1imidacloprid and1.6mg·L^-1carbendazim seriously destroyed cell membrane and organelles ofthe tomato.4. The soil sucrase and alkaline phosphatase activities were activated to the maximum level withthe complexes application of0.07mg·L^-1imidacloprid and0.4mg·L^-1carbendazim. No matter singleuse or their combinations,0.07mg·L^-1imidacloprid and0.4mg·L^-1carbendazim increased theconcentrations of soil microbial biomass carbon and nitrogen, which could promote the tomato growthand soil nutrient cycling.5.0.07mg·L^-1imidacloprid and0.4mg·L^-1carbendazim were conducive to the bacterial growthand reproduction.2.8mg·L^-1imidacloprid and1.6mg·L^-1carbendazim significantly inhibited bacterialgrowth and reproduction. The effects of different concentrations of imidacloprid and carbendazim on fungal community structure were opposite to bacterial.In summary, no matter single use or their combinations, when the imidacloprid concentrationwithin0-0.07mg·L^-1(equivalent goods recommended amount in the concentration of0-0.30kg·ha^-1)and carbendazim concentration within0-0.4mg·L^-1(equivalent goods recommended amount in theconcentration of0-1.80kg·ha^-1), the pesticides application promoted tomato growth and soil nutrientcycling. When the imidacloprid concentrations were higher than0.14mg·L^-1(equivalent to two timesthe upper limit of commodity recommended amount) and carbendazim concentrations were higher than0.8mg·L^-1(equivalent to two times the upper limit of commodity recommended amount), the pesticidesapplication inhibited tomato growth and soil nutrient cycling to a certain extent. Especially whenimidacloprid concentration up to2.8mg·L^-1and carbendazim concentration up to1.6mg·L^-1, whethersingle use or their combinations, the pesticides application seriously impeded the growth of tomatoplants and produced irreversible damaging effects on tomato cell.