【作者】 崔翠；

【导师】 张硕新；

【作者基本信息】 西北农林科技大学 ， 生态学， 2012， 博士

【摘要】 化感作用是指一个活体植物（供体植物）通过茎叶挥发、淋溶、根系分泌等途径向环境中释放其产生的某些化学物质，从而影响周围植物（受体植物）的生长和发育的化学生态学现象。核桃（Juglans regia L.）是胡桃科（Juglandaceae）核桃属（Juglans L.）落叶乔木，在我国栽培历史悠久，分布很广，资源十分丰富。然而，核桃的生长会抑制周围其它作物的生长发育。本研究以渭北黄土区农林复合系统主要经济树种核桃为供体植物，在探讨其化感物质对几种常见作物化感作用的基础上，利用气相色谱-质谱联用技术分析了核桃树根际土壤浸提液的成分和核桃树根系分泌物浸提液的组分，同时研究了其对核桃树根际土壤微生态的影响，为渭北黄土区的农林复合系统优化经营模式的实践提供科学依据和奠定理论基础。结果表明：1.核桃叶水浸提液对受体植物贝母、小麦、萝卜、花生、绿豆和白菜的种子发芽和幼苗生长都有一定的影响，且表现出明显的化感效应和浓度效应，适宜受体植物为萝卜和白菜。2.不同生长年限的核桃树根际土壤四种不同溶剂（20%甲醇、甲醇、乙酸乙酯和正己烷）的浸提液均有明显的化感效应；2年生核桃树根际土壤浸提液含有酯类、醇类、烷烃类、烯烃类、酮类、醛类、萘类、醌类、酸类、酚类、酰胺类、苯类等12大类91种有机化合物；3年生核桃树根际土壤浸提液包含烷烃类、烯烃类、醇类、酸类、酯类、醛类、酮类、酚类、酰胺类、醌类等11大类90种有机化合物；4年生核桃树根际土壤浸提液含有烷烃类、烯烃类、醇类、酸类、酯类、酮类、酚类、醛类、醌类、酰胺类、苯环类、芳香烃类、氰类、苯类等14大类89种有机化合物。3.不同生长年限的核桃树根系分泌物均呈现出明显的化感效应；2年生核桃树根系分泌物浸提液中含有烷烃类、烯烃类、醇类、酸类、酯类、酰胺类、酚类、醌类、苯类等9大类35种有机化合物；3年生核桃树根系分泌物浸提液含有烷烃类、醇类、酸类、酯类、酮类、酰胺类、酚类、醌类、烯烃类、醛类等10大类43种有机化合物；4年生核桃树根系分泌物浸提液包含烷烃类、醇类、酸类、酯类、胺类、酚类、烯烃类、醌类、芳香烃类等9大类50种有机化合物。4.在核桃树生长过程中，根际土壤有机养分和无机养分含量基本高于非根际土壤，随着生长年限增加，土壤有机质、全氮、速效氮、全钾及速效钾呈现逐年升高的趋势，土壤全磷、速效磷及pH值呈现逐年降低的趋势，且除了pH值随着土壤深度的增加明显升高，土壤养分均随着土层深度的增加呈现明显降低的趋势；与非根际土壤相比，核桃树根际土壤中的过氧化氢酶、脲酶、磷酸酶和蔗糖酶活性都有不同程度的降低，四种酶活性的空间变化随着土层剖面的加深而活性降低，说明土壤中各种酶的活性可能和核桃根系的分泌物有关，脲酶和蔗糖酶活性均随生长年限的增加而增强，磷酸酶活性随生长年限的增加而降低，随着生长年限的不同，各种土壤酶活性的变化规律不一致，可能是因为核桃根系分泌物的种类和数量以及根系周围的微生物对每种土壤酶的合成影响不同所致；在不同生长年限的核桃树根际土壤中，土壤微生物数量发生了较大的变化，与非根际土壤相比，土壤中细菌和真菌随着生长年限的增加而增多，放线菌则表现出随着生长年限的增长而降低，且均随着土层深度的增加呈现明显降低的趋势。更多还原

【Abstract】 Allelopathy is one of the most important chemoecological phenomena, which refersto one plant (donor) impact the growth and development on its neighboring plants (accepter)through the release of secondary metabolism chemical compounds into the environment viavolatilization, leaching, excretion, and decomposition. Walnut (Juglans regia L.) is awidespread tree in walnut genus (Juglans) of walnut family (Juglamdacea). It is plantedoriginally for a long history in China. However, all of the foliage, root and fruit peel of walnutcan inhibit the growth of neighbor plants signigicantly. In this study, bioassay methods wereused to probe into the walnut allelopathic effect on receiver plants, and chemical componentswere analyzed and identified with gas chromatograph-mass spectrometer (GC-MS), therhizosphere soil extracting effects with different solvents，root exudates extracts of walnuttrees, and the effect of root exudates on rhizosphere soil microecology were studied to providea scientific basis and the theoretical basis for optimizing the practice of the economic modelfor agroforestry systems in the loess area of nothern Wei River. The results showed:1. Walnut leaf aqueous extract affected the seed germination and seedling growth offritillaria, wheat, turnip, peanut, mung bean, and cabbage, showing significant allelopathiceffect and concentration effect. Receiver plants for further study were selected, which wereturnip and cabbage.2. The rhizosphere soil of walnut trees was extracted with different solvents (20%methanol, methanol, ethyl acetate, and n-hexane). Bioassay methods were used to probe intothe four different extracts of walnut trees rhizosphere soil, which showed the significantallelopathic effect. Totally12sorts91components were identified from the rhizosphere soilof2-year-old walnut trees, which included esters, alcohols, alkanes, olefins, ketones,aldehydes, naphthalenes, acids, phenols, amides, benzene, and quinones; totally11sorts90components were identified from the rhizosphere soil of3-year-old walnut trees, whichincluded alkanes, olefins, alcohols, acids, esters, aldehydes, ketones, phenols, and amides;totally14sorts89components were identified from the rhizosphere soil of4-year-old walnuttrees, which included alkanes, olefins, alcohols, acids, esters, ketones, phenols, aldehydes, quinones, benzene rings, aromatic hydrocarbons, cyanogens, benzenes.3. Root exudates extracts of walnut trees in different ages all showed the significantallelopathic effect. Totally9sorts35components were identified from the root exudates of2-year-old walnut trees, which included alkanes, olefins, alcohols, acids, esters, amides,phenols, quinones, benzenes; totally10sorts43components were identified from the rootexudates of3-year-old walnut trees, which included alkanes, alcohols, acids, esters, amides,ketones, phenols, quinones, olefins, and aldehydes; totally9sorts50components wereidentified from the root exudates of4-year-old walnut trees, which included alkanes, alcohols,acids, esters, amines, phenols, olefins, quinones, aromatic hydrocarbons.4. In the growth process of walnut trees, the contents of organic and inorganic nutrientsin rhizosphere soil were basically higher than those in bulk soil and the contents of organicmatter, total N, available N, total K, and available K increased with the age increasing; total Pand available P content and pH value reduced with the age increasing, and excepting the pHvalue significantly increased with the increase of soil depth, obviously decreased with theincrease of soil depth. Compared to bulk soil, the catalase, urease, phosphatase and sucraseactivities in rhizosphere soil of walnut trees decreased and activities of the four enzymesdecreased with the depth of spatial profile, indicated that the soil enzymes activities may berelated with the root secretion. Urease and sucrase activities in rhizosphere soil increased withthe ages of walnut trees; phosphatase activities decreased with the ages of walnut trees. In therhizosphere soil of walnut trees in different ages, variation rules of different soil enzymeactivities were inconsistent, this was because of rhizosphere of the walnut secretion types andquantity, and microorganism that displayed the different functions to each kind of soilenzyme’s synthesis. The microorganism numbers in the rhizosphere soil varied significantlywith ages of walnut trees. Compared with the bulk soil, the bacterium and fungi quantity inrhizosphere soil increased along with the age increasing, actinomycetes quantity reducedalong with the age increasing and bacterium, fungi, and actinomycetes quantity reduced withthe depth of spatial profile.更多还原