外源棕榈酸对连作西瓜生长及土壤微生物的影响

发布时间：2018-06-28 10:00

本文选题：棕榈酸 + 西瓜生长　；参考：《东北农业大学》2015年硕士论文

【摘要】：西瓜(Citrullus lanatus L.)是世界性园艺作物,中国西瓜栽培面积占世界第一位。而随着西瓜种植面积逐年扩大,连作栽培不可避免,连作障碍的问题也随之而来。因连作而引发的西瓜枯萎病可使西瓜减产15%~85%,是最为严重的西瓜病害。为解决西瓜连作导致的枯萎病害,已成为现代农业生产中急需解决的问题。研究发现外源物质的使用能够有效的缓解瓜类连作障碍及病害蔓延,但机理不明。本文以温室连作5年的西瓜土壤为研究对象,以西瓜为试材,采用模拟盆栽试验的方法,研究了外源添加棕榈酸对连作西瓜生长及土壤微生物的影响,筛选出提高西瓜抗病增产及抑制西瓜枯萎病菌的最适棕榈酸浓度。采用常规方法研究了不同浓度棕榈酸对西瓜生长以及土壤理化性质的影响,利用稀释平板法、q PCR及PCR-DGGE技术分析了不同浓度棕榈酸对西瓜根区土壤微生物菌落数量、群落组成及多样性的影响,从而揭示适宜浓度棕榈酸提高西瓜枯萎病的抗性及促进西瓜生长的机理,为指导西瓜生产上施行对枯萎病的生态防控提供理论依据和技术支撑。本研究的主要结论如下:(1)棕榈酸在低浓度(0.25-1 mmol/kg)增加了西瓜根系总长度、根系表面积和根系体积,增加了西瓜植株的蔓长、茎粗和干鲜重,提高了西瓜的根系活力、叶绿素含量和产量。其中以1 mmol/kg处理西瓜长势最好,产量最高。高浓度棕榈酸(4 mmol/kg)则显著抑制西瓜生长。(2)外源棕榈酸可有效防治西瓜枯萎病,不同浓度棕榈酸(0.25-4 mmol/kg)处理的西瓜枯萎病发病率和病情指数均低于对照处理,1 mmol/kg棕榈酸处理西瓜枯萎病发病率和病情指数最低,显著低于对照及其它处理。(3)西瓜生长后期(60d),低浓度棕榈酸(0.25-1 mmol/kg)显著提高土壤有效磷含量,高浓度棕榈酸(4 mmol/kg)显著降低土壤有效磷含量;土壤中有机质含量随着棕榈酸浓度增加,棕榈酸浓度为4 mmol/kg时土壤有机质含量最高。土壤EC值随西瓜生长整体呈现先升高后降低的趋势,西瓜生长中期(40 d)1 mmol/kg棕榈酸处理土壤EC值最高。西瓜生长后期,土壤p H随棕榈酸浓度增加呈先升高后降低的趋势,1 mmol/kg土壤p H最高。(4)随着西瓜定植天数增加,各处理西瓜根区土壤中细菌、真菌以及尖孢镰刀菌的菌落数量不断增加。每个取样时期中随棕榈酸浓度增加,土壤细菌和真菌菌落数量先增加后降低。西瓜生长前中后期,0.25 mmol/kg处理中尖孢菌菌落数最高且尖孢菌所占真菌百分比显著高于对照,4 mmol/kg处理中尖孢菌菌落数最低,1 mmol/kg处理尖孢菌所占真菌百分比最低。(5)随着西瓜定植天数增加,各处理土壤中细菌、真菌及西瓜专化型尖孢镰刀菌群落丰度不断增加。西瓜生长前中期,1 mmol/kg棕榈酸细菌和真菌拷贝数高于对照及其它处理,0.5 mmol/kg处理土壤中镰刀菌拷贝数最高,显著高于对照及其它处理,4 mmol/kg棕榈酸细菌、真菌及尖孢镰刀菌拷贝数均最低,显著低于对照。(6)添加不同浓度棕榈酸后,连作土壤细菌和真菌的条带数、均匀度指数和Shannon-Wiener指数在不同生长时期均发生了变化,1 mmol/kg棕榈酸处理细菌和真菌的条带数、均匀度指数和Shannon-Wiener指数显著高于对照及其他处理。高浓度棕榈酸(4 mmol/kg)处理细菌条带数、均匀度指数和Shannon-Wiener指数高于对照,高浓度棕榈酸(4mmol/kg)处理真菌条带数、均匀度指数和Shannon-Wiener指数低于对照。(7)不同浓度棕榈酸均显著地抑制了尖孢镰刀菌菌丝的生长,孢子萌发、产孢量,且呈现随着浓度增加,对于枯萎病菌抑制作用增强。2mmol/L棕榈酸溶液对西瓜枯萎病菌的抑制作用最大,显著高于其它各个处理。综上所述,施用适宜浓度外源棕榈酸(1 mmol/kg)处理能显著促进西瓜植株生长,提高西瓜单果重,有效防控西瓜枯萎病发生,能保持相对较高的土壤微生物群落结构多样性及细菌数量,同时降低土壤中Fusarium菌的数量及比例。
[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.
【学位授予单位】：东北农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S651;S154.3

【参考文献】