Effects Of Pesticides,Fertilizing And Inter-cropping On Growth And Soil Physical-chemical Properties In Tung Oil Tree Seedlings Of Three Gorges Reservoir Area

Tung oil tree plantations are mainly located in the Three Gorges Reservoir,a large area of tung oil tree forest has destructed because of tung oil market has downturn in the 1990s,tung oil tree of remaining is poor quality and semi-wild.Large-scale tung oil tree will have been restored and developed,which will be the only way for tung oil tree industry development in the Three Gorges Reservoir Area.Pesticide and fertilizer is important to ensuring tung oil tree would has had a high yield and quality.The ecological environment is fragile,the quality of soil environment has become worsen and non-point source pollution which has become an important environmental issue in the Three Gorges Reservoir Area.Unreasonable application of pesticides and fertilizers will increase non-point source pollution in the Three Gorges Reservoir Are where large-scale tung oil tree will have been developed.so,tung oil tree seedlings were used to study the process,we study on the effects of pesticides,fertilization and inter-planting on growth and soil physical-chemical properties in tung oil tree seeding.,which provides a theoretical reference for scientific guidance planting tung oil tree and control the pollution in the Three Gorges reservoir area.Results show that:(1)A pot experiment was conducted to studying the growth condition of tung oil tree seeding and changes of soil chemical properties under different concentrations of paraquat(Technical/water=1/50,1/100,1/200,1/400and1/800)andfenvalerate-dimerthoate(Technical/water=1/125,1/250,1/500,1/1000andl/2000),and water as a control(CK).Results show that:1)Comparing with the CK,the soil pH was increased under different concentrations treatment of paraquat,and soil pH was decreased under different concentrations treatment of fenvalerate-dimerthoate,but the difference was not significant(P>0.05).2)The contents of soil organic and total N were decreased under different concentrations treatment of paraquat and fenvalerate-dimerthoate.Organic matter and nitrogen contents of each treatment group showed a decreasing trend with prolonged treatment.The soil nitrogen matter content was decreased under the high concentrations of paraquat and fenvalerate-dimerthoate treatment,while the soil nitrogen content was increased under the conventional concentration(paraquat=1/400,fenvalerate-dimerthoate=1/1000)treatment,and the soil nitrogen contents of each treatment group showed a decreasing trend with prolonged treatment.the contents of total P,total K,effective P,available K were higher than CK,the soil total P,total K,effective P and available K contents of each treatment group showed a decreasing trend with prolonged treatment.3)The soil urease,protease and catalase activity were significantly reduced under different concentrations treatment of paraquat and fenvalerate-dimerthoate(P<0.05),the higher the concentration,the stronger the inhibition was.The soil urease,protease and catalase activity were showed a decreasing trend with prolonged treatment,but the higher the concentration,the smaller the rate of increase.4)Fenvalerate-dimerthoate in conventional concentration(1/1000)treatment had inhibition on the growth of plant height of tung oil tree,while has promoted on the growth of diameter of tung oil tree,paraquat in conventional concentration(1/400)treatment has promoted on the growth of plant height and diameter of tung oil tree.The growth of plant height and diameter of tung oil tree were decreased under the high concentrations of paraquat and fenvalerate-dimerthoate treatment,and the higher the concentration,the more significant inhibition.5)The biomass and shoot ratio of tung oil tree were decreased under different concentrations treatment of paraquat and fenvalerate-dimerthoate,and the higher the concentration,the more significant inhibition.6)The chlorophyll content had decreased under treatment of paraquat and fenvalerate-dimerthoate,and with increasing concentration,the lower the chlorophyll content.The Fv/Fm,qP and ETR of tung oil tree under treatment of paraquat and fenvalerate-dimerthoate were significantly lower than the CK,but its high NPQ,which shows that the pesticide has changed distribution of PS ?excitation energy,has reduced the absorption of light energy and dissipated excess excitation energy through improved heat dissipation,which protect the photosynthetic mechanism to preventing excessive decline in photosynthetic rate.Summary,it indicates that paraquat and fenvalerate-dimerthoate have an obviously effect on the soil physical-chemical properties and the growth of tung oil tree seeding in a high concentration.Under the high concentrations of paraquat and fenvalerate-dimerthoate treatment,the contents of soil organic and total N were decreased,the soil urease,protease and catalase activity were significantly reduced,tung oil tree seeding absorbing nutrients from the soil and growth were being Suppressed,the shoot ratio,chlorophyll content and photosynthetic efficiency of tung oil tree were decreased.However,that paraquat and fenvalerate-dimerthoate have an not obviously effect on the soil physical-chemical properties and the growth of tung oil tree seeding in conventional concentration treatment,which can make soil harden and acidification by long-term application of pesticides.(2)In this paper,1-year-old tung oil tree grew in different three conditions:inter-cropping with soybean(T)(there are two rows of soybean seedlings between every two rows tung,tung oil tree seedlings from 50cm,soybean spacing of 50cm �50cm)and pure forest(CK).Results show thatl:)The Pn?Gs and Tr of tung oil tree leaf in inter-cropping soybean were lower than those without soybean treatment,(P>0.05);WUE with inter-cropping soybean were higher than those without soybean(P<0.05);inter-cropping with soybean can reduces the LCP,LSP and CCP of tung oil tree seedlings,which demonstrate that inter-cropping with soybean can help to reduce water loss tung oil tree seedlings and resist drought stress by reducing the photosynthetic capacity of tung oil tree seedlings.2)Furthermore,the fitting degree of Pn-PAR and Pn-CO2 response curve were 0.97 and 0.99,respectively.3)Inter-cropping soybean did not affect the growth of the tung oil tree seedlings,which can help tung oil tree seedlings improving the ability of using low light and accumulating the photosynthetic products.Results show that intercropping soybeans in a proper density can reduce photo synthetic capacity of the tung oil tree seedlings,improve photosynthetic performance,and increase drought tolerance of mulberry as well,which has a positive effect on tung oil tree seedlings withstand high temperature within summer in chongqing.(3)This study analyzed the effects of the right amount(1000g/pot)of pig organic manure and(50g/pot)compound fertilizer(20-18-10)on growth and soil nutrients in Three Gorges Reservoir tung oil tree seedlings under potted conditions.Results show that:Comparing with non-organic manure soil(CK),after using pig organic manure for 3 months,the soil pH was increased,the difference was not significant(P>0.05),but after using compound fertilizer for 3 months,the soil pH was decreased,and the difference was significant(P<0.05).2)The soil under both manure organic and compound fertilize treatments that contents of organic matter(P<0.05),total N and nitrogen(P<0.05)were increased,but the total P,effective P,total K and available K were decreased,which shows that organic fertilizer making the soil nutrients be more easy absorbed by tung oil tree seedlings.3)Under both manure organic and compound fertilize treatments,the growth of height,ground diameter and plant biomass were increased,while also promoting the tung oil tree seedling root growth that making keep a high ability to absorb nutrients in the late growth.Pig organic manure and compound fertilizer(20-18-10),with the right amount,it can increase the content of soil organic matter and nitrogen,and making the soil nutrients be effectively absorbed and seedling growth.However,under soil conditions within the scope of the experiment,long-term application of compound fertilizer(20-18-10)can cause soil acidification.So,combining pig organic manure application,can avoid acidification caused by long-term application of fertilizer.