本文選題：棕櫚酸 + 西瓜生長�。� 參考：《東北農業(yè)大學》2015年碩士論文

【摘要】：西瓜(Citrullus lanatus L.)是世界性園藝作物,中國西瓜栽培面積占世界第一位。而隨著西瓜種植面積逐年擴大,連作栽培不可避免,連作障礙的問題也隨之而來。因連作而引發(fā)的西瓜枯萎病可使西瓜減產15%~85%,是最為嚴重的西瓜病害。為解決西瓜連作導致的枯萎病害,已成為現代農業(yè)生產中急需解決的問題。研究發(fā)現外源物質的使用能夠有效的緩解瓜類連作障礙及病害蔓延,但機理不明。本文以溫室連作5年的西瓜土壤為研究對象,以西瓜為試材,采用模擬盆栽試驗的方法,研究了外源添加棕櫚酸對連作西瓜生長及土壤微生物的影響,篩選出提高西瓜抗病增產及抑制西瓜枯萎病菌的最適棕櫚酸濃度。采用常規(guī)方法研究了不同濃度棕櫚酸對西瓜生長以及土壤理化性質的影響,利用稀釋平板法、q PCR及PCR-DGGE技術分析了不同濃度棕櫚酸對西瓜根區(qū)土壤微生物菌落數量、群落組成及多樣性的影響,從而揭示適宜濃度棕櫚酸提高西瓜枯萎病的抗性及促進西瓜生長的機理,為指導西瓜生產上施行對枯萎病的生態(tài)防控提供理論依據和技術支撐。本研究的主要結論如下:(1)棕櫚酸在低濃度(0.25-1 mmol/kg)增加了西瓜根系總長度、根系表面積和根系體積,增加了西瓜植株的蔓長、莖粗和干鮮重,提高了西瓜的根系活力、葉綠素含量和產量。其中以1 mmol/kg處理西瓜長勢最好,產量最高。高濃度棕櫚酸(4 mmol/kg)則顯著抑制西瓜生長。(2)外源棕櫚酸可有效防治西瓜枯萎病,不同濃度棕櫚酸(0.25-4 mmol/kg)處理的西瓜枯萎病發(fā)病率和病情指數均低于對照處理,1 mmol/kg棕櫚酸處理西瓜枯萎病發(fā)病率和病情指數最低,顯著低于對照及其它處理。(3)西瓜生長后期(60d),低濃度棕櫚酸(0.25-1 mmol/kg)顯著提高土壤有效磷含量,高濃度棕櫚酸(4 mmol/kg)顯著降低土壤有效磷含量;土壤中有機質含量隨著棕櫚酸濃度增加,棕櫚酸濃度為4 mmol/kg時土壤有機質含量最高。土壤EC值隨西瓜生長整體呈現先升高后降低的趨勢,西瓜生長中期(40 d)1 mmol/kg棕櫚酸處理土壤EC值最高。西瓜生長后期,土壤p H隨棕櫚酸濃度增加呈先升高后降低的趨勢,1 mmol/kg土壤p H最高。(4)隨著西瓜定植天數增加,各處理西瓜根區(qū)土壤中細菌、真菌以及尖孢鐮刀菌的菌落數量不斷增加。每個取樣時期中隨棕櫚酸濃度增加,土壤細菌和真菌菌落數量先增加后降低。西瓜生長前中后期,0.25 mmol/kg處理中尖孢菌菌落數最高且尖孢菌所占真菌百分比顯著高于對照,4 mmol/kg處理中尖孢菌菌落數最低,1 mmol/kg處理尖孢菌所占真菌百分比最低。(5)隨著西瓜定植天數增加,各處理土壤中細菌、真菌及西瓜專化型尖孢鐮刀菌群落豐度不斷增加。西瓜生長前中期,1 mmol/kg棕櫚酸細菌和真菌拷貝數高于對照及其它處理,0.5 mmol/kg處理土壤中鐮刀菌拷貝數最高,顯著高于對照及其它處理,4 mmol/kg棕櫚酸細菌、真菌及尖孢鐮刀菌拷貝數均最低,顯著低于對照。(6)添加不同濃度棕櫚酸后,連作土壤細菌和真菌的條帶數、均勻度指數和Shannon-Wiener指數在不同生長時期均發(fā)生了變化,1 mmol/kg棕櫚酸處理細菌和真菌的條帶數、均勻度指數和Shannon-Wiener指數顯著高于對照及其他處理。高濃度棕櫚酸(4 mmol/kg)處理細菌條帶數、均勻度指數和Shannon-Wiener指數高于對照,高濃度棕櫚酸(4mmol/kg)處理真菌條帶數、均勻度指數和Shannon-Wiener指數低于對照。(7)不同濃度棕櫚酸均顯著地抑制了尖孢鐮刀菌菌絲的生長,孢子萌發(fā)、產孢量,且呈現隨著濃度增加,對于枯萎病菌抑制作用增強。2mmol/L棕櫚酸溶液對西瓜枯萎病菌的抑制作用最大,顯著高于其它各個處理。綜上所述,施用適宜濃度外源棕櫚酸(1 mmol/kg)處理能顯著促進西瓜植株生長,提高西瓜單果重,有效防控西瓜枯萎病發(fā)生,能保持相對較高的土壤微生物群落結構多樣性及細菌數量,同時降低土壤中Fusarium菌的數量及比例。
[Abstract]:Watermelon (Citrullus lanatus L.) is the world's gardening crop. The cultivated area of watermelon in China is the first in the world. With the growing area of watermelon growing year by year, continuous cropping is inevitable, and the problem of continuous cropping is followed. The watermelon wilt caused by continuous cropping can reduce the yield of 15%~85% and is the most serious watermelon disease. The problem of wilt disease caused by watermelon continuous cropping has become an urgent problem in modern agricultural production. It is found that the use of exogenous substances can effectively alleviate the continuous cropping obstacle and disease spread, but the mechanism is unknown. In this paper, watermelon soil for 5 years in greenhouse was used as the research object, and watermelon as the test material, the simulation pot experiment was used. The effects of exogenous palmitic acid on the growth of continuous cropping watermelon and soil microorganism were studied. The optimum concentration of palmitic acid was selected to improve the resistance and yield of watermelon and to inhibit the pathogen of watermelon wilt. The effects of palmitic acid on the growth of watermelons and the physical and chemical properties of watermelons were studied by conventional methods. The dilution plate method, Q PCR and PCR- were used to study the effects of palmitic acid on the growth of watermelon and the soil physical and chemical properties. The effects of palmitic acid on the number, composition and diversity of soil microbial colonies in the root zone of watermelon were analyzed by DGGE technology, which revealed the mechanism of the suitable concentration of palmitic acid to improve the resistance of Watermelon Wilt and the mechanism of promoting the growth of watermelon. It provided the theoretical basis and technical support for the ecological control of the wilt disease in watermelon production. The main conclusions of this study are as follows: (1) palmitic acid at low concentration (0.25-1 mmol/kg) increases the total root length, root surface area and root volume of watermelon, increases the length of the plant, the stem diameter and dry fresh weight, and improves the root vigor, chlorophyll content and yield of watermelon. The best growth trend of watermelon is 1 mmol/kg, and the yield is the highest. High concentration palmitic acid (4 mmol/kg) significantly inhibited the growth of watermelon. (2) exogenous palmitic acid could effectively control watermelon wilt. The incidence and index of wilt disease of watermelon with different concentrations of palmitic acid (0.25-4 mmol/kg) were lower than that of control. The incidence of Watermelon Wilt and the disease index of 1 mmol/kg palmitic acid treatment were the lowest, significantly lower than that of the treatment. (3) (3) late growth of Watermelon (60d), low concentration of palmitic acid (0.25-1 mmol/kg) significantly improved soil effective phosphorus content, high concentration of palmitic acid (4 mmol/kg) significantly reduced soil available phosphorus content, soil organic matter content with palmitic acid concentration increased, palmitic acid concentration of 4 mmol/kg soil organic matter content is the highest. Soil EC value. As the whole growth of watermelon first increased and then decreased, the EC value of soil EC in the middle period of Watermelon (40 d) 1 mmol/kg palmitic acid treatment was the highest. The soil P H increased first and then decreased with the increase of the concentration of palmitic acid, and the highest P H in 1 mmol/kg soil. (4) the soil bacteria in the root zone of watermelon were treated with the increase of the number of planting days in the watermelon. The colonies of fungi and Fusarium oxysporum were increasing. With the increase of palmitic acid concentration in each sampling period, the number of soil bacteria and fungi colonies increased first and then decreased. In the middle and late period of the growth of watermelon, the number of apex spores in the 0.25 mmol/kg treatment was the highest and the percentage of fungi was significantly higher than that of the control, and the 4 mmol/kg treatment was at the middle point. The number of spores was the lowest, and the percentage of fungi accounted for 1 mmol/kg was the lowest. (5) the abundance of bacteria, fungi and Fusarium oxysporum in each treatment soil increased as watermelon planting days increased. The number of 1 mmol/kg palmitic acid bacteria and fungi was higher than the control and other treatments, 0.5 mmol/k in the middle period of the growth of watermelon. The number of Fusarium Fusarium in G treatment was the highest, significantly higher than the control and other treatments. 4 mmol/kg palmitic acid bacteria, fungi and Fusarium oxysporum were the lowest, significantly lower than the control. (6) after adding different concentrations of palmitic acid, the number of strips of soil bacteria and fungi, the average evenness index and the Shannon-Wiener index were all at different growth stages. The number of 1 mmol/kg palmitic acid treated bacteria and fungi, the evenness index and the Shannon-Wiener index were significantly higher than those of the control and other treatments. The high concentration palmitic acid (4 mmol/kg) treated the number of bacterial bands, the evenness index and the Shannon-Wiener index were higher than the control, and the high concentration palmitic acid (4mmol/kg) treated the number of fungal bands, and the uniformity of the band number of the high concentration palmitic acid (4mmol/kg) was uniform. The degree index and Shannon-Wiener index were lower than those of the control. (7) palmitic acid at different concentrations inhibited the growth of mycelium of Fusarium oxysporum, spore germination and sporulation, and increased with the concentration. The inhibition effect of.2mmol/L palmitic acid on Fusarium Wilt of Fusarium wilt was greatest, which was significantly higher than that of other species. In summary, the application of suitable concentration of exogenous palmitic acid (1 mmol/kg) can significantly promote the growth of watermelon plants, increase the single fruit weight of watermelons, effectively control the occurrence of watermelon wilt, and maintain the relatively high soil microbial community structure diversity and the number of bacteria, and reduce the amount and proportion of Fusarium bacteria in the soil at the same time.
【學位授予單位】：東北農業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：S651;S154.3

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