西瓜连作障碍缓解技术及其机理研究

发布时间：2017-12-31 19:30

  本文关键词：西瓜连作障碍缓解技术及其机理研究　出处：《西北农林科技大学》2016年博士论文　论文类型：学位论文

  更多相关文章： 西瓜 连作障碍 缓解技术 土壤特性 枯萎病 细菌多样性 高通量测序

【摘要】：西瓜(Citrullus lanatus(Trunb.)Matsum and Nakai)在我国具有较高的经济效益,但是其连作障碍严重影响西瓜生产可持续发展。如何解决连作障碍问题已成为世界性难题。西瓜连作障碍的实质是西瓜连续栽培引起土壤特性发生了变化。大量研究表明,轮作和增施有机肥以及高温闷棚可以缓解西瓜连作障碍。但很少有人对缓解连作障碍中土壤发生变化的机理进行系统的研究。基于此,本试验以大蒜为轮作作物,牛粪和作物秸秆为有机肥,进行田间试验和室内培养分析,研究其对西瓜生长和枯萎病菌的影响,从对土壤理化性状、生物学性状和细菌群落多样性影响的角度,探讨其在缓解西瓜连作障碍中的作用,为其在生产中的应用提供理论依据。主要结果如下:1、进行连续三年的田间西瓜栽培试验,通过轮作大蒜和增施牛粪的技术,分别研究它们对西瓜生长和土壤特性的影响。结果表明:西瓜连作后,植株长势明显变弱,而实施大蒜轮作和施牛粪都可促进西瓜植株生长,增加产量,缓解这种现象。至三年试验结束时,轮作大蒜和施牛粪分别使产量增加了67%和112%,枯萎病发病率降低38%和50%,而两者相结合可增产138%,枯萎病发病率降低57%,这说明二者相结合具有叠加效应。进一步研究发现,轮作大蒜和增施牛粪显著增加了细菌和放线菌的数量,降低了真菌的数量,同时,增加了细菌和真菌群落比值;无论是轮作大蒜还是增施牛粪均显著增加了土壤中各酶(蛋白酶、脲酶、过氧化氢酶、蔗糖酶、多酚氧化酶和碱性磷酸酶)的活性;降低了土壤中总酚的含量;促进了土壤养分(速效氮、速效磷、速效钾和有机质)的释放,提高了连作地土壤的肥力。因此,可能是轮作大蒜更有利于土壤中细菌数量的增加和真菌数量的减少,从而减轻枯萎病的发病率;而牛粪对增加土壤酶活性的贡献率更大,有利于土壤整体质量的改良,从而增加西瓜产量。2、在温室夏季休闲期,采用短期淹水高温闷棚的技术,研究其对后茬西瓜生长和土壤特性的影响。结果表明:短期淹水高温闷棚使西瓜植株的株高增加29%,枯萎病发病率减少48%,西瓜产量提高57%。这可能主要是由于短期淹水高温闷棚极显著降低了土壤的容重,减少了各养分含量在土壤中的积累,有效降低了土壤的含盐量,土壤的总酚含量显著下降,细菌和放线菌数量显著增加,真菌数量显著减少。对西瓜生长与土壤特性进行相关性分析表明,植株发病率与细菌数量呈显著负相关,与全酚含量呈显著正相关,而与真菌和放线菌数量不相关;产量与盐分含量呈负相关,与细菌和放线菌的数量呈正相关。因此,可能短期淹水高温闷棚对细菌菌落的影响在减轻植株发病率和增加产量方面的作用更大。3、利用植物的化感作用,采用将供体植物(大蒜、茼蒿、万寿菊、芹菜、小麦、三叶草)的秸秆加入到西瓜连作土中的技术,研究不同秸秆腐解物浸提液对西瓜幼苗生长、植株发病率以及对西瓜枯萎病菌的影响。结果表明:不同秸秆腐解物的浸提液增加了西瓜种子胚根主根的长度和侧根的数量,提高了幼苗干重的根冠比,降低了西瓜幼苗枯萎病的病情指数。分析它们的化感效应发现,不同秸秆腐解物均促进了西瓜尖孢镰刀菌菌丝的生长,而显著降低了菌丝的生物量,不同程度的抑制孢子萌发;对尖孢镰刀菌菌液的酶活性(淀粉酶、蛋白酶、果胶酶、纤维素酶)的化感作用因作物种类而不同,但大蒜对这四种酶活性均表现为化感抑制作用。因此,不同秸秆腐解物对西瓜枯萎病菌可能不是直接的抑制作用,而是通过增加微生物的活性产生代谢物质,从而抑制病原菌的生长。4、研究和分析了不同秸秆腐解在提高西瓜植株抗病性的过程中对西瓜连作土壤特性的影响。结果表明:不同秸秆腐解物显著增加了连作土的微生物总量,促进了细菌在微生物总量中所占的比例;各腐解物的土壤酶活性得到了不同程度的提高,以大蒜的蛋白酶、脱氢酶和碱性磷酸酶活性最高,小麦的脲酶活性最高,三叶草的土壤蔗糖酶活性最高。不同秸秆的腐解显著增加了连作土各养分的释放,速效氮和速效磷的含量随着腐解时间的延长处于增加的趋势,速效钾的含量先升高后降低,而有机质含量受腐解时间的影响不大。各腐解物土壤的含盐量随着养分的释放也相应增加。土壤pH值与参试作物种类有关。进一步的化感效应分析表明,不同腐解物对细菌和放线菌含量为化感促进作用,大蒜和万寿菊对真菌含量及pH值变化为化感抑制作用。总之,不同秸秆腐解物对西瓜枯萎病菌的作用,可能是土壤微生物群体作用的结果,当土壤中微生物群落结构越丰富,多样性越高时,对抗病原菌的能力越强。5、为进一步探讨植物与微生物的互作关系,利用Illumia HiSeq高通量测序平台对16S rDNA的V4区扩增子进行测序,研究不同秸秆腐解物对西瓜连作地土壤中细菌群落多样性及丰度的影响。结果表明:在门水平上(相对丰度排名前10),不同秸秆腐解物对土壤中细菌的优势菌群产生影响,各处理的优势菌门为变形菌门、厚壁菌门和拟杆菌门,而对照(连作土)的优势菌群有酸杆菌门、芽单胞菌门、浮霉菌门、泉古菌门、放线菌门和绿弯菌门;进一步统计物种数量在各水平上的差异,以门水平为例,大蒜和万寿菊比对照各多了10个门,茼蒿比对照多了8个门,芹菜比对照多了6个门,小麦和三叶草比对照分别少了7个和6个。因此,不同秸秆腐解物通过增加土壤中细菌群落的相对丰度和物种多样性,提高有益菌群在土壤中的比例,降低有害菌群在土壤中的相对含量,从而对病原菌产生拮抗作用。
[Abstract]:Watermelon (Citrullus Lanatus (Trunb.) Matsum and Nakai) is high in China's economic benefits, but the impact of serious continuous cropping watermelon production sustainable development. How to solve the problems of continuous cropping obstacle has become a worldwide problem. The essence of watermelon continuous cropping obstacle is caused by continuous cultivation of watermelon soil properties changed. A large number of studies show that rotation and organic fertilizer and high temperature disinfection can alleviate the watermelon continuous cropping obstacle. But there are few people to study systematically the mechanism to reduce changes of continuous cropping obstacles in. Based on this, the test for crop rotation with garlic, cow dung and crop straw as organic fertilizer, field experiment and laboratory analysis, to study its effect on the growth and Fusarium Wilt of watermelon, from the soil physical and chemical properties, biological characteristics and bacterial community diversity influence angle, discusses the ease of watermelon continuous cropping obstacle In effect, provide a theoretical basis for its application in production. The main results are as follows: 1, the field of watermelon cultivation test in three consecutive years, through the rotation of garlic and fertilizing cow dung, respectively to study their effects on the growth of watermelon and soil properties. The results show that the West as urizura, plant growth significantly weak, while the implementation of garlic rotation and applying cow dung can promote watermelon plant growth, increase yield, to alleviate this phenomenon. The end of the three year test, rotation of garlic and applying cow dung respectively. The yield was increased by 67% and 112%, wilt disease incidence rate decreased by 38% and 50%, and the combination of the two can be increased by 138%, wilt the incidence rate decreased by 57%, indicating that the combination of the two has additive effect. Further studies showed that the number of rotation of garlic and fertilizing cow dung significantly increased the bacteria and actinomycetes, reduced the number of fungi, at the same time, increase the population of bacteria and fungi Fall ratio; whether it is still adding garlic rotation manure significantly increased the soil enzyme (protease, urease, catalase, invertase, polyphenol oxidase and alkaline phosphatase) activity; reduce the content of total phenol in soil; promote the soil nutrients (available nitrogen, available phosphorus, available potassium and organic matter) release, improve the continuous cropping soil fertility. Therefore, may be more conducive to reducing the number of garlic rotation increased the quantity of soil bacteria and fungi, thus reducing the incidence of Fusarium wilt; and cow manure on soil enzyme activities increased the contribution rate of greater improvement to the overall quality of the soil, thereby increasing the watermelon the yield of.2 in summer fallow period in greenhouse, the waterlogging high temperature disinfection technology, study the influence of post harvest growth of watermelon and soil properties. The results showed that waterlogging high temperature disinfection watermelon plant height increased by 29%, The incidence of Fusarium Wilt of watermelon yield increase of 57%. decreased by 48%, which may be mainly due to short-term flooding high temperature disinfection significantly decreased soil bulk density, reduce the accumulation of nutrient content in the soil and reduce soil salt content, total phenol content in soil decreased significantly, the number of bacteria and actinomycetes significantly increase the number of fungi decreased significantly. The growth of watermelon and soil characteristics of the correlation analysis showed that the plant was negatively related to the number and incidence of bacteria was positively correlated with the total phenol content, and put the number of Actinomyces and fungi and related; yield was negatively correlated with salt content, and the number of positive bacteria and actinomycetes bacteria related. Therefore, the possible short-term flooding high temperature disinfection effect on the bacterial colonies to reduce plant morbidity and increase the role of greater.3 effect by plants, the donor plants (garlic, Chrysanthemum, marigold, celery, wheat, clover) straw into watermelon continuous cropping soil in the technology of different straw extracts on the growth of watermelon seedlings, plant incidence and effect on Watermelon Fusarium wilt. The results showed that different straw hydrolysate extract increased the number of watermelon seeds the radicle root length and lateral root, improve the seedling dry weight of root shoot ratio, reduce disease index of Fusarium Wilt of watermelon seedlings. Analyze their allelopathic effects that different straw decomposition increased Watermelon Fusarium oxysporum mycelia growth, and significantly reduced the biomass of mycelium, spores of different inhibition the degree of germination; enzyme activity of Fusarium oxysporum bacteria (amylase, protease, pectinase, cellulase) allelopathy for different crop species, but garlic on the activities of these four enzymes showed allelopathic effect. Therefore, The different straw hydrolysate on Fusarium oxysporum may not directly inhibit, but produce metabolites by increasing microbial activity, thereby inhibiting the growth of.4 pathogens, research and analysis of the effects of different straw soil characteristics on the West in the process of improving urizura resistance in watermelon plants. The results showed that different straw hydrolysate significantly increased the amount of soil microorganisms in continuous cropping, promote the bacteria in microbial accounted for the proportion of the total; soil enzyme activity in different composts were improved in different degrees, with garlic protease, alkaline phosphatase activity and dehydrogenase activity of urease was highest, the highest wheat, soil invertase activity was the highest in three grass. Different straw Composts significantly increased soil nutrient release, available nitrogen and available phosphorus content with the decomposition time in increasing trend, available The potassium content increased first and then decreased, while the content of organic matter is not affected by the decay time. The quantity of salt decomposition with soil nutrient release also increased. The pH value of soil and crop species tested. Further analysis showed that the allelopathic effect, different composts on bacteria and actinomycetes the content of bacteria for allelopathy effect, garlic and marigold on fungi content and pH value change in the sense of inhibition. In short, different straw composts on Watermelon Fusarium wilt effect may be soil microbial groups result, when more abundant in soil microbial community structure, diversity is higher, the ability against pathogens the stronger the bacteria.5, to further explore the interaction between plants and microorganisms, using Illumia HiSeq sequencing platform V4 of 16S rDNA amplicons were sequenced to study the effects of different straw composts on bacterial watermelon continuous cropping soil 缇よ惤澶氭牱鎬у強涓板害鐨勫奖鍝，

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