【作者】 肖雪梅；

【导师】 程智慧；

【作者基本信息】 西北农林科技大学 ， 蔬菜学， 2013， 博士

【摘要】 设施黄瓜的连作障碍日趋严重，已成为制约黄瓜可持续生产的主要限制因子。本试验采用大蒜或青蒜与大棚黄瓜连续套作的种植模式，分别从黄瓜生长发育、生理变化及产量品质，土传病害发生、土壤生物特性、养分有效性及化学性状变化等方面，系统研究套蒜消减黄瓜连作障碍的效果及机理，为建立大蒜和青蒜与黄瓜高效可持续套作模式提供理论和技术依据。主要结果如下：1.第一年套作，除G064品种外，其他品种大蒜均显著促进黄瓜株高和茎粗增长，而青蒜则抑制黄瓜生长。第二、三年套作，大蒜和青蒜均显著增加黄瓜株高、茎粗、雌花数、总叶片数和第五功能叶面积。套作大蒜和青蒜可增加黄瓜叶片中叶绿素含量，显著降低丙二醛含量和SOD、POD及CAT活性。2.从第一套作年春茬开始，套作大蒜和青蒜的产量优势开始显现。第一套作年春茬，套作大蒜品种G005比黄瓜单作提高产量13.4%；第二套作年秋茬，套作青蒜提高产量11.9%。至第三年套作，套作产量优势逐渐减弱，与单作无显著差异。第一套作年秋茬，套作不同品种大蒜和青蒜对黄瓜品质无显著影响。第一年春茬，套作处理可显著提高黄瓜果实Vc含量。第二套作年，套作黄瓜果实干物质、可溶性蛋白和Vc含量均不同程度地提高。第三套作年，大蒜和青蒜可显著增加黄瓜果实干物质、可溶性蛋白、Vc和可溶性糖的含量。3.随种植年限增加，连作黄瓜枯萎病和根结线虫病发病率逐渐上升，而套作大蒜和青蒜均显著降低枯萎病和根结线虫的发病率，且青蒜的效果更强。套作大蒜和青蒜可显著增加土壤细菌和放线菌数量，减少土壤真菌数量。套作第一年，土壤微生物种类和数量与动态取样时间及大蒜品种有关，规律不稳定。第二、三年，套作大蒜和青蒜对土壤细菌、真菌和放线菌数量的影响规律稳定。随种植年限的增加，土壤细菌和放线菌数量呈先缓慢下降后急速上升，然后再下降的变化趋势；土壤真菌数量呈“M”型动态变化，总体呈增加趋势。套作大蒜和青蒜显著影响土壤酶活性，影响程度与土壤酶种类及套作年限有关。除第一年秋茬和第三年春茬以外，套蒜处理均显著提高了土壤过氧化氢酶活性。第一年秋茬，套作不同品种大蒜和青蒜均显著降低土壤蔗糖酶和脲酶活性，其后的套作处理反而显著提高这两种酶的活性。连续3年套作处理均显著提高了土壤碱性磷酸酶活性。4.套作大蒜和青蒜显著增加了土壤碱解氮含量。与单作相比，秋茬黄瓜套作大蒜和青蒜后土壤速效磷和速效钾含量增加，但随着大蒜和青蒜的生长，土壤速效磷和速效钾含量减少；至下一年春季大蒜和青蒜收获后，套作系统的土壤速效磷和钾的含量逐渐增加，最终趋于一致或高于单作。随种植年限增加，连作土壤pH值呈下降趋势，而套作处理先降低后提高土壤pH值，对土壤酸度有一定的稳定能力。从第二套作年开始，大蒜和青蒜均显著降低土壤EC值，缓解连作土壤次生盐渍化。5.大棚套作大蒜的收获期比露地提早30～40d。青蒜可于秋季连续收割4茬，且均具有商品性。综合效益分析表明，套作大蒜和青蒜可显著增加大棚单位时空的净产值。第一年套作大蒜G005、G064和G087分别提高净产值15.6%、17.2%和19.6%，套作青蒜提高净产值达33.6%；第二年套作大蒜G087和青蒜分别提高净产值19.0%和38.1%；第三年套作大蒜G087和青蒜分别提高净产值14.7%和28.3%。6.盆栽试验研究套作不同数量青蒜对连作黄瓜养分吸收和土壤微生物群落结构的影响。结果显示，套作青蒜可显著提高黄瓜生物量，增加植株中N、P、K、Ca和Mn含量，减少Mg、Zn和Fe含量。同时增加土壤有机质含量，平衡土壤氮、磷、钾比例。套作青蒜显著增加黄瓜根际和非根际土壤细菌、放线菌、菌根真菌、原生生物和细菌/真菌的数量，降低真菌数量，使土壤由真菌型向细菌型转化。套作中等数量青蒜（每株黄瓜300g、450g和600g蒜头）效果为好。7.离体抑菌试验研究大蒜根系分泌物和青蒜挥发物分别对黄瓜土传和叶部病害的抑制作用。结果证实，大蒜根系分泌物可显著抑制黄瓜枯萎病菌菌丝生长和孢子萌发，且随浓度增加抑制效果增强。当大蒜根系分泌物浓度为0.28mg·ml^-1时，对菌丝和孢子的抑制率分别为40.0%和60.4%。青蒜挥发物显著抑制黄瓜靶斑病菌菌丝生长和孢子萌发，当浓度为2.50mg·ml^-1时，对菌丝和孢子的抑制率分别为55.3%和93.3%。扫描和透射电子显微镜观察菌丝体形态和结构发现，大蒜根系分泌物和青蒜挥发物处理的菌丝体皱褶、干瘪、易断裂，细胞壁变薄、破裂，胞内空腔增多，胞质不均匀，核区不明显。总结连续3年试验结果认为，套作大蒜或青蒜可以消减黄瓜连作障碍，其机理与大蒜根系分泌物及活体挥发物对黄瓜生长和生理的化感调节作用、对黄瓜根部和叶部病害的抑菌作用、对土壤微生物数量和群落结构、土壤酶活性及土壤养分有效性等调节作用有关，大棚黄瓜套作大蒜或青蒜都是大棚黄瓜高效可持续生产模式。更多还原

【Abstract】 Continuous cropping obstacles are becoming more and more serious. It has restrictedsustainable production of cucumber in protected cultivation. In this study, garlic or greengarlic was continuously intercropped with cucumber to investigate the effect and mechanismof intercropping alleviating continuous cropping obstacles of cucumber in plastic tunnel. Thegrowth and development, physiological changes, disease incidence, yield and quality ofcucumber, and microbial feature, nutrient status, pH and EC value of the soil was analysed.The objective of this study is to provide a theoretical and technical basis to the establishmentof the efficient and sustainable intercropping patterns of garlic and green garlic withcucumber. The main results summarized as follows:（1） Except cultivar G064, intercropping with other cultivars of garlic significantlyimproved the growth of cucumber plant height and stem diameter. Conversely, intercroppingwith green garlic inhibited cucumber growth in the first intercropping year. The intercroppedgarlic and green garlic significantly enhanced the plant height, stem diameter, number offemale flowers and total number of leaves, and the leaf area of the fifth functional leaf ofcucumber in the second and third cropping year. Compared with monocropping, intercroppingwith garlic and green garlic significantly increased chlorophyll content, decreased MDAcontent, SOD, POD and CAT activity of cucumber leaves.（2） Since spring cultivation of the first intercropping year, yield advantages ofintercropping with garlic and green garlic started to appear, compared with monocropping. Inspring cultivation of the first year, garlic cultivar G005increased cucumber yield by13.4%;in autumn cultivation of the second year, green garlic increased cucumber yield by11.9%.There was no significant difference of cucumber yield between intercropping andmonocropping in the third year. In autumn cultivation of the first intercropping year, differentcultivars of garlic and green garlic had no significant effect on cucumber fruit quality. In spring cultivation of the first year, intercropping treatment significantly increased Vc contentof cucumber fruit. Dry matter, soluble protein and Vc content were significantly improved byintercropping in the second year. Intercopping with garlic and green garlic significantlyincreased the content of dry matter, soluble protein, Vc and soluble sugar of cucumber fruit inthe third year.（3） The inhibitory effect of cultivar G064and green garlic among treatments was better.With continuous cropping increasing, the incidence rate of cucumber fusarium wilt and rotknot nematode disease was increasing in monocropping. Intercropping treatmentssignificantly inhibited the incidence rate of cucumber fusarium wilt and the nematode, and thegreen garlic showed stronger inhibitory effect. Intercropping with garlic and green garlicsignificantly increased the amount of soil bacteria and actinomyteces, while decreased theamount of soil fungi, compared with monocropping. In the first year, soil microbial speciesand amount was related to the dynamic sampling date and garlic cultivar. The previous trendwas not stable. In the second and third year, the effect trend of intercropping with garlic andgreen garlic on the soil microbe was stable. With the planting year increasing, the amount ofbacteria and actinomyteces was first decreasing slowly, then increasing rapidly and lastdecreasing; the amount of fungi was increasing as “M” dynamic change. Intercropping withgarlic and green garlic significantly influenced the activities of soil enzymes, which werevaried with enzyme species and intercropping years. Except autumn cultivation in the firstyear and spring cultivation in the third cropping year, intercropping significantly improvedsoil catalase activity. In the autumn cultivation of the first year, intercropping systemssignificantly reduced soil invertase and urease activities. Subsequently, intercroppingtreatment significantly improved enzymes activities. In the three continuous intercroppingyears, intercropping systems significantly improved soil alkaline phosphatase activity.（4） Intercropping with garlic and green garlic significantly increased soil available Ncontent, compared with monocropping. In autumn cultivation each intercropping year,intercropping treatments increased soil available P and K at the early growth stage ofcucumber. However, with the garlic and green garlic growing, the available P and K contentdecreased in intercropping systems. Up to the spring cultivation in the next year, the availableP and K content in the intercropping systems was no difference or higher than themonocropping after garlic and green garlic harvest. With the planting year increasing, soil pHvalue was gradually declining in monocropping. Intercropping treatment first reduced thenenhanced soil pH value, stabilizing soil acidity. From the second to the third intercroppingyear, intercropping treatments significantly reduced the soil EC value. It demonstratedintercropping treatments alleviated replant soil secondary salinization. （5） The harvest time of garlic in the intercropping systems planting in plastic tunnel was30⁴0days earlier than in the open field. Green garlic was continuously cut for four times inthe autumn season and had good commercial character. By productivity benefit analysis,intercropping garlic and green garlic significantly increase net output each planting year andarea in plastic tunnel. In the first year, intercropping with garlic cultivar G005, G064andG087increased the net output by15.6%,17.2%and19.6%, respectively; green garlicincreased the net output by33.6%. In the second year, the net output was increased by19.0%and38.1%when intercropping with garlic and green garlic. In the third year, the net outputwas increased by14.7%and28.3%in garlic-cucumber and green garlic-cucumberintercropping system, respectively.（6） Pot experiment was carried out to investigate the effect of intercropping withdifferent amounts of green garlic on nutrient uptake and soil microbial community structure.The results demonstrated that intercropping with green garlic significantly increasedcucumber biomass, N, P, K, Ca and Mn content, while decreased Mg, Zn and Fe content.Moreover, intercropping improved soil organic matter content and balance the proportion ofN, P and K. Intercropping with green garlic significantly increased population of soil bacteria,actinomycetes, AM fungi, Protozoa and B/F ratio, while decreased population of total fungi.Intercropping make soil from a more bacterial dominated to a more fungal communitystructure. Intercropping with moderate amounts of green garlic （300g,450g and600g garlicbulbs for each cucumber） showed better effect.（7） Antibacterial test in vitro was carried out to investigate inhibitory effect of garlic rootexudates and green garlic volatiles on growth of soil-borne and leaf disease. The resultsshowed that garlic root exudates significantly inhibited mycelial growth and sporegermination of cucumber fusarium wilt, and the effect was increasing with the concentions ofgarlic root exudates increasing. Inhibition rate of mycelial growth and spore germination was40.0%and60.4%when the concentration was0.28mg·ml^-1. Green garlic volatilessignificantly inhibited mycelial growth and spore germination of cucumber target spot.Inhibition rate of mycelial growth and spore germination was55.3%and93.3%when theconcentration was2.50mg·ml^-1. Mycelial morphology and structure observed by scanningand transmission electron microscopy demonstrated that treated mycelium was ruga, wizenedand easy to breakage; had thinner cell wall, more cavity, nonuniform cytoplast andunconspicuous nucleus zone.The experiment of continuous intercropping in three years demonstrated thatintercropping with garlic or green garlic alleviated continuous cropping obstacles ofcucumber. The mechanism were related to the allelopathy regulating effect of garlic root exudat and live volatile matter on the growth and physiology of cucumber, the incidence ofroot and leaf diseases, the microbial population and community structure, the soil enzymesactivities and soil nutrient availability. Intercropping garlic or green garlic with cucumber is aefficient and sustainable productive pattern.更多还原