Study On Regulation Of Arbuscular Mycorrhizal Fungi In Strawberry Root Allelopathic Stress

With modern intensive agriculture, high cropping index trends, combined with limited arable land, cultivation conditions constraints, economic interests and other constraints led to crop cropping obstacles widespread, cropping obstacles has become an urgent bottleneck problem to solve in agricultural production of China and the world. Strawberry is the world’s largest berry fruit, its nutrient rich, planting easy, cycle short, and develops very quickly in our country in recent years. But due to continuous cropping, the main producing areas appear strawberry yield and quality declined and pest diseases become seriously year by year, restricting the development of strawberry. Therefore, exploring the mechanism of strawberry continuous cropping obstacles and control measures is important and urgent.The test study on the effects of inoculated arbuscular mycorrhizal fungi(AMF) and other beneficial microorganisms in strawberry under root allelopathic stress, such as the effects to strawberry growth and development, protection enzymes activity, soil enzyme activity, rhizosphere soil allelochemicals, root rhizosphere phenolic acids content and so on. Hope to further reveal the regulation mechanism of strawberry cropping obstacles with AMF and other beneficial microorganisms inoculation. The main results are as follows:1. Applied allelochemicals P-hydroxybenzoic acid solution significantly inhibited the normal growth and development of strawberry;reduced the number of strawberry leaves, plant height, stem diameter, chlorophyll content and root vigor; improve leaf proline(Pro), soluble protein, malondiadehyde(MDA) content; inhibited leaf protective enzymes peroxidase(POD), catalase(CAT)and soil urease, phosphatase activity. On the same conditions, plant damage degree significantly increased with exogenous acid concentrations increased and stress time prolonged, made the plants weaker, root system smaller, thereby poison strawberry.2. Inoculated AMF and Bacillus mucilaginosus mixed agents could significantly alleviate the impacts and damages of exogenous phenolic acids, to a certain extent, promote the normal growth and development of Strawberry. Under allelopathic stress, compared with unvaccinated strawberries, inoculated strawberry improved the plant height, leaf number, stem diameter, root activity, enhanced the root growth; eased the adverse effects on the strawberry root in varying degrees; increased the chlorophyll content, improve the photosynthesis and nutritional status; reduced Pro and MDA content and increased solubility sugar and soluble protein content in strawberry leaves, can maintain the inside and outside cells osmotic balance and mitigate the impact on the cell membrane; enhanced the protective enzyme superoxide dismutase(SOD), POD, CAT activity, could ease the damage of induced oxidative stress; improve the root soil urease, phosphatase, invertase activity, can improve soil quality levels and relieve the soil environment changes. Thus effectively inhibit the allelochemicals stress damage on strawberry plant growth, and enhance the plant’s resistance. Even the mixed bacteria agent could play a stronger role than single agents under strong stress.3. In this experiment, used the ultrasonic wave and ethyl acetate extracti to extract the allelopathic substances of strawberry rhizosphere, the chemical components were analyzed by gas chromatography-mass spectrometry(GC-MS). Got more than 50 kinds of active ingredients, benzoic acid derivatives such as Dibutyl phthalate, 1,2-Benzenedicarboxylic acid, diisooctyl ester, 1,2-Benzenedicarboxylic acid, butyl 2-methylpropyl ester and alkanes, alkenes, aromatic hydrocarbons, aliphatic alcohols, aldehydes, ketones and acids compared with the literature, most of them are kinds of allelochemicals. Among the detected substances, Friedelan-3-one had higher relative contents, was the first time detected in the rhizosphere soil of strawberry. The benzoic acid derivatives which were detected verify the benzoic structural component is existin strawberry rhizosphere soil phenolic acid compounds, verify p-hydroxybenzoic acid which contains benzoic acid structure as allelochemicals treat to strawberry is feasible.4. Strawberry rhizosphere soil phenolic acids were extracted by 1mol/L Na OH solution, and each phenolic acids content was measured by HPLC quantitative. Detected six kinds of phenolic substances in strawberry rhizosphere soil. According to the order of the peak, they are p-hydroxybenzoic acid, lilac acid, vanillin, p-coumaric acid, ferulic acid and benzoic acid. When p-hydroxybenzoic acid concentration range is 0-20mg/L, inoculation of Glomus mosseae and Bacillus mucilaginosus mixed agents could significantly reduce the p-hydroxybenzoic acid content, also have different effects on other phenolic substances.