【作者】 孔瑞芳；

【导师】 南志标；

【作者基本信息】 兰州大学 ， 植物病理学， 2009， 硕士

【摘要】 苏丹草[Sorghum sudanense(Piper)Stapf]是禾本科高粱属一年生优良牧草。病害是苏丹草生产与利用的主要限制因素之一。本论文通过对我国现有的8个苏丹草品种(系)的种带真菌进行研究,初步明确了其种带真菌区系及对苏丹草种子和幼苗的致病力,筛选出防治效果较好的杀菌剂品种,主要结果如下:1.自8个苏丹草品种(品系)的种子上共分离获得16属20种真菌,其中细交链孢(Alternaria alteranata)、交链孢(Alternaria sp.)、壳二孢(Ascochyta sp.)、黑曲霉(Aspergillus niger)、黄曲霉(A.spergillusflavus)、根腐离蠕孢(Bipolaris sorokiniana)、新月弯孢(Curvularia lunata)、大斑德氏霉(Drechslera turcnica)、串珠镰刀菌(Fusariummonilifome)、青霉(Penicillium sp.)、黑根霉(Rhizopus stolonfer)和粉红单端孢(Trichothecium roseum)为苏丹草常见的种带真菌,而枝孢(Cladosporium sp.)、燕麦镰刀菌(F.avenaceum)、禾谷镰刀菌(F.graminearum)、茎点霉(Phoma sp.)、疫霉(Phytophthora sp.)、立枯丝核菌(Rhizoctonia solani)、束状匐柄霉(Stemphyliumsarciniforme)和轮枝菌(Verticillium sp.)等则稀有报道。其中自未经表面消毒的种子分离出真菌14属17种,自表面消毒处理的种子分离出12属16种。种子表面消毒处理未显著减少带菌种数,但显著降低了带菌率。种子解剖检验证实,多数种带真菌存在于颖壳(12种)和种皮(13种)上,其次为胚乳(10种),少数在胚内(7种)。2.所有参试的20种真菌分离物均可在苏丹草幼苗根组织的表面生长,除交链孢、曲霉、青霉和黑根霉未观测到侵入外,其余15种真菌均可不同程度的侵入根组织并产生病斑。采用纸上发芽法和纸卷法测定了除立枯丝核菌外的19种种带真菌对种子发芽和幼苗生长的影响。与未接种的对照相比,大部分种带真菌均显著降低了种子的发芽率、根长和苗长。其中根腐离蠕孢、新月弯孢、大斑德氏霉、燕麦镰刀菌、禾谷镰刀菌、串珠镰刀菌和粉红单端孢对种子致病力最强,分别降低发芽率27.5%、16.7%、27.5%、35.3%、31.6%、34.4%和19.5%,降低苗长44.7%、40.8%、49.0%、46.5%、58.7%、39.6%和46.9%,降低根长61.8%、32.3%、56.4%、61.1%、60.0%、57.7%和47.3%。综合以上,初步认定根腐离蠕孢、新月弯孢、大斑德氏霉、燕麦镰刀菌、禾谷镰刀菌、串珠镰刀菌、立枯丝核菌和粉红单端孢是苏丹草的种带病原真菌。3.用4种杀菌剂处理0007、1044和89-106号苏丹草种子,结果显示杀毒矾对种带真菌的防效显著高于福美双、甲霜灵和甲基硫菌灵等其他三种参试杀菌剂(P＜0.05),分别为87.8%、89.4%和92.1%,并显著或极显著提高了根长和芽长,根长分别增加了12.2%、7.24%和20.1%,芽长分别增加了12.7%、10.6%和9.4%。更多还原

【Abstract】 Sudangrass(Sorghum sudanense(Piper) Stapf) is an important annual gramineous sorghum forage in China.With the increasing of planting areas,disease became one of the main limiting factors for sudangrass production.The information on the seedborne fungi which may the main reason caused sudangrass disease and the information on sudangrass disease control are scare.In this study,seedbome fungi of 8 cultivars of sudangrass detection,fungi invasiveness to seedlings of sudangrass,and fungi pathogenicity to seeds and seedlings of sudangrass were determined;The fungicides and the methods of seed treatment to control the seedborne disease of the grass was also studied.The results were summarized as the follows:1.Twenty fungal species of 16 genera were isolated and identified from 8 cultivars of sudangrass.Among the fungi isolated,Alternaria alteranata,Alternaria sp.,Ascochyta sp.,Aspergillus niger,A.spergillusflavus,Bipolaris sorokiniana,Curvularia lunata, Drechslera turcnica,Fusarium monilifome,PeniciUium sp.,Rhizopus stolonifer and Trichothecium roseum were the most common isolated,and Cladosporium sp.,F. avenaceum,F.graminearum,Phoma sp.,Phytophthora sp.,Rhizoctonia solani Stemphylium sarciniforme and Verticillium sp.were isolated frequently.Seeds surface sterilization reduced the percentage of fungal isolation.Seventeenth species belonging to 14 genera were isolated and identified from seeds without surface sterilization and sixteenth species belonging to 12 genera were isolated and identified from surface sterilized seeds.For the sites of the fungi isolated from the seeds,in order of decreasing frequency of fungal species,were seed coat(13),pericarp(12),endosperm(10) and embryo(7).2.All the 20 fungi isolated from the seeds of sudangrass was observed grown on the surface of the root of sudangrass seedlings and caused lesion on the root except Alternaria sp.,Aspergillus spp.,Penicillium sp.and Rhizopus stolonifer.The effects of of the isolated seedborne fungi(exclude R.solani)on the germination and seedling vigor index of seeds inoculated with spore suspension were studied by using the standard blotter method and the paper towel method.Compared with the uninoculated treatment,the germination of seeds,shoot length and root length of seedlings were significantly decreased by inoculation of the most fungi(P＜0.05).Among which,B. sorokiniana,C.lunata,D.turcnica,F.avenaceum,F.graminearum,F.monilifome and Tr. Roseum shown the highest pathogenesis to sudangrass.The percentage of seed germination were reduced by 27.5%、16.7%、27.5%、35.3%、31.6%、34.4%and 19.5%respectively; The shoot length of seedling were reduced by 44.7%、40.8%、49.0%、46.5%、58.7%、39.6%and 46.9%respectively;The root length of seedling were reduced by 61.8%, 32.3%、56.4%、61.1%、60.0%、57.7%and 47.3%respectively.Based on the above results,we concluded that B.sorokiniana,C.lunata,D.turcnica, F.avenaceum,F.graminearum,F.monilifome,R.solani and Tr.Roseum were the pathogeic fungi of the sudangrass seeds.3.Among the four fungicide tested in this study,seeds of 0007,1044 and 89-106 treated with oxadixyl shown the best inhibition to fungi infection,the inhibition reached 87.8%,89.4%and 92.1%respectively(P＜0.05).Meanwhile seeds treated with oxadixyl significantly increased the root length of the seedlings of 0007,1044 and 89-106 by 12.2%, 7.24%and 20.1%respectively,and also increased the shoot length by 12.7%、10.6%and 9.4%respectively.更多还原