Allelopathy Study Of Garlic Rootaqueous Extractson Watermelon In Continuous Cropping Soil

Recent years, continuous cropping obstacle problem in facility cultivation is common,however, watermelon as a kind of crop that it is not fit for continuous cropping, theoccurrence of the continuous cropping obstacle seriously affect the supply of watermelonproduction and market demand. Now study about how to ease of watermelon continuouscropping is less, grafting method is used to relieve the problem of watermelon continuouscropping obstacles, but with the increase of grafting fixed number of year, it appearsdifferent levels of the continuous cropping obstacle. To solve these problems, the pottedplant experiment was curried out to investigated the effects of six different concentrationsof garlic root aqueous extract on plant growth and physiological indicators.of small-fruitwatermelon in continuous cropping soil and the change of watermelon rhizosphere microecological environments to explore the allelopathy of garlic root extraction on continuouscropping watermelon plant. At the same time it provides the theory basis for overcome theobstacle of watermelon in continuous cropping soil.The main results were as follows:1. Under normal condition, the seed germination and bud seedlings growth of watermalonwere promoted under low concentration of garlic root aqueous extract (5and8g/L) treatmentand were inhibited under high concentration of garlic root aqueous extract (10,20,30,40g/L) treatment. The application of garlic root aqueous extract at its5g/L concentrationcould more significantly promote seed germination and bud seedlings growth ofwatermalon,.2. the continuous cropping soil leaching solution inhibitory the small watermelon seedgermination and seedlings growth. The application of low concentration of garlic rootaqueous extract (5,8,10and20g/L) reversed the negative effects ofcontinuous croppingsoil leaching solution on the seed germination and seedlings growth of small-fruitwatermelon, but high concentration (30,40g/L) further improved the inhibitory effects ofcontinuous cropping soil leaching solution.3.Continuous cropping decreased net photosynthesis rate (Pn) of watermelon leavesand inhibited the growth of watermelon.While the application of garlic root aqueousextracts at5,8,10and20g/L can effectively alleviate the inhibition effects of continuouscropping on growth of watermelon by increasing photosynthetic pigment content,photosynthetic capacity of watermelon leaves and photosynthetic activity of PS Ⅱ,reducing photodamage and making energy distribution of PSⅡ more reasonable. But theapplication of garlic root aqueous extracts at30and40g/L further improved the inhibitoryeffects of continuous cropping on the growth of watermelon plants.4.The significant increase in MDA, H2O2contents and decreas in the activities ofSOD、POD and CAT and key enzyme related with the AsA-GSH cycle in watermelon leaves caused by continuous cropping resulted in the reduction of reactive oxygen speciesscavenging activity and increase of lipid peroxidation and plant growth inhibition, whereasapplication of low concentration garlic root aqueous extract (5,8,10and20g/L) couldincrease the activities of SOD, CAT, POD, APX, MDHAR, DHAR and the endogenousreducting power levels, which could enable the plants in a reduced state, resulting in theeffectively removement of H2O2and alleviation of lipid peroxidation. especially applicationof garlic root aqueous extract at its5g/L concentration could more significantly alleviatecontinuous cropping-induced oxidative damage. But the application of garlic root aqueousextracts at30and40g/L further improved the inhibitory effects of continuous cropping onthe growth of watermelon plants.5.Continuous cropping decreased watermelon plant rhizosphere soil bacteria andactinomycetes quantity and increased fungi quantity.At the same time soil B/F value wasreduced. While the application of garlic root aqueous extracts at5,8,10and20g/Lconcentration could effectively alleviate the inhibition effects of continuous cropping ongrowth of watermelon by increasing the activity of enzyme of continuous croppingwatermelon rhizosphere soil and increasing the activity of (beneficial microbial) bacteriaand actinomycetes and inhibit the activity of (harmful microorganisms) fungus.Socontinuous cropping soil micro ecological environment has be beneficial improvement and5g/L concentration could more significantly improved watermelon rhizosphere microecological environments. The application of garlic root aqueous extracts at30and40g/Lfurther improved the continuous cropping soil of soil borne disease occurs, caused the soilenvironment more adverse influence on the growth of small watermelon plant.