【作者】 赵金莉；

【导师】 贺学礼；

【作者基本信息】 河北大学 ， 动物学， 2007， 博士

【摘要】 在毛乌素沙地,生长着一些沙生先锋植物-克隆植物,它们在沙地中的出现,使生境条件得以改善,为其他物种定居提供了可能。克隆植物之所以能够耐受外界的恶劣环境的原因,除本身的植物生理特点外,其与土壤微生物特别是丛枝菌根真菌的共生也是重要原因之一。本研究把荒漠环境中的克隆植物与AM真菌共生关系作为切入点,系统研究了荒漠环境中克隆植物根围AM真菌的多样性、时空分异规律、克隆植物生长对AM真菌多样性和菌根形成的影响及AM真菌对克隆植物生长和抗旱性的影响。结果如下：毛乌素沙地克隆植物根际存在丰富的AM真菌多样性,在采集的原始土壤样品和诱集培养土壤中共分离出4属23种AM真菌,其中球囊霉属(Glomus)15种,无梗囊霉属(Acaulospora)5种,巨孢囊霉属(Gigaspora)2种,盾巨孢囊霉属(Scutellospore)1种；已鉴定18种,尚有5个未定种,初鉴定为新种。不同属种的AM真菌生态分布亦存在差异,红色盾巨孢囊霉仅出现在沙鞭根际；海得拉巴球囊霉、缩球囊霉和卷曲球囊霉仅分布在羊柴根际；长孢球囊霉、珠状巨孢囊霉和蜜色无梗囊霉仅出现在油蒿根际。聚丛球囊霉和长孢球囊霉是研究站样地的特有种类,而多梗球囊霉和海得拉巴球囊霉是榆林样地的特有种类。毛乌素沙地克隆植物能够与AM真菌形成良好的菌根共生体。其中沙鞭和羊柴的丛枝菌根结构类型为Arum型,油蒿为Ⅰ-型。同时,在羊柴菌根中发现一种新的类似丛枝的特殊结构。毛乌素沙地克隆植物根际AM真菌和丛枝菌根定殖具有明显的空间异质性。在土壤相对贫瘠、透气性强的流动或半固定沙丘上,孢子密度较低,却具有较高的AM真菌定殖率和感染强度,0-50cm各土层间无显著差异；在土壤相对肥沃、透气性较差的固定沙丘上,具有较高的孢子密度,但AM真菌定殖率和感染强度较低,0-30cm土层显著高于30-50cm土层。毛乌素沙地克隆植物根际AM真菌和丛枝菌根定殖亦具有明显的季节性。在春季(5月),孢子密度最高,而丛枝菌根侵染率最低；夏季(7月),丛枝菌根侵染率达最大值,孢子密度显著下降；秋季(10月),孢子密度最低,丛枝菌根定殖率下降。AM真菌和丛枝菌根定殖率受地理环境和土壤因子的影响。随着温度上升和水分梯度升高,AM真菌孢子密度下降；随着速效N含量增加和有机质含量减少,AM真菌孢子密度下降。丛枝菌根定殖率与土壤温度和有机质含量成正相关。克隆植物生长对AM真菌物种多样性和丛枝菌根形成的影响因植物种类和样地不同而有所不同。(1)沙鞭通过克隆生长侵入灌丛空地后,在研究站样地AM真菌多样性指数由0.2690上升为0.5566,AM真菌孢子密度和丛枝菌根不同结构定殖率均显著增加；在榆林样地AM真菌多样性指数由0.7227上升为0.9368,AM真菌孢子密度、菌丝、丛枝和总定殖率均显著提高,泡囊定殖率也有所增加,但未达显著水平。(2)羊柴通过克隆生长侵入灌丛空地后,在研究站样地AM真菌多样性指数由0.8377上升为1.0308,AM真菌孢子密度和丛枝定殖率显著增加,而泡囊定殖率显著降低,菌丝和总定殖率也有所下降,但未达显著水平；在榆林样地AM真菌多样性指数由1.0338下降为0.9587,AM真菌孢子密度和丛枝定殖率显著增加,而菌丝、泡囊和总定殖率均显著降低。油蒿根际土著AM真菌对促进油蒿生长和增强抗旱性具有显著效应。接种AM真菌显著提高了油蒿的分枝数、植株鲜重和干重,改善了叶片水分状况,增强了叶片细胞质膜的稳定性,部分保护酶活性提高,渗透调节物质可溶性糖的含量提高。本论文研究成果丰富了荒漠恢复生态学的基础理论,为菌根生物技术在荒漠植被恢复和生态重建中的应用提供了科学依据和种质资源。更多还原

【Abstract】 In Mu Us sandland, there live some kinds of clonal plants. As pioneer plants, their emergence improved the living conditions for colonization of other plants. Despite their own physiological characters, their endurance capability for the atrocious circumstance also rest with their symbiosis with edaphon, especially the AM fungi. In this research, the spatial and temporal variation and diversity of AM fungi from the rhizosphere of clonal plants, effects of the growth of clonal plant on diversity of AM fungi and arbuscular mycorrhiza, effects of AM fungi on the growth and drought resistance of clonal plant were systemically investigated. Results were showed as follows:An abundant diversity of AM fungi was found in the rhizosphere of clonal plants in Mu Us sandland. Isolation and purification of the mycorrhizal fungi led to the identification of 23 species belonged to four genera:15 to the genus Glomus,5 to Acaulospora,2 to Gigaspora and 1 to Scutellospore.5 uncertain species were identified as unrecorded species. Ecological distribution of the diverse species is different. Scutellospore erythropa only occurred in the rhizosphere of Psammochloa villosa. Glomus hydembadensis, Glomus constrictum and Glomus convolutum only appeared in the rhizosphere of Hedysarum laeve. Glomus dolichosporum, Gigaspora margarita and Acaulospora mellea only occurred in the rhizosphere of Artemisia ordosica. Glomus aggregatum and Glomus dolichosporum were own species in Yanjiuzhan, Glomus hydembadensis and Glomus multicaule were own species in Yulin.Clonal plants can form well symbionts with AM fungi in Mu Us sandland. Psammochloa villosa and Hedysarum laeve form the Arum-type mycorrhizas, Artemisia ordosica has the intermediate type. At the same time, a kind of special structure that is similar with arbuscule was found in the mycorrhiza of Hedysarum laeve.A distinct temporal variation of AM fungi and colonization of arbuscular mycorrhiza from the rhizosphere of clonal plants was found. On the mobile dunes or semifixed dunes where soils are infertile and with better soil air-permeability, the spore density was lower and colonization rate and intensity were higher. There has no significant difference among the 5 soil layers sections. On the fixed dunes where soils are fertile and with wore soil air-permeability, the spore density was higher and colonization rate and intensity were lower, the colonization rate and intensity were significantly higher at 0～30cm sections than 30～ 50cm sections.Seasonal variation of AM fungi and colonization of arbuscular mycorrhiza from the rhizosphere of clonal plants was found also. The spore density was highest and colonization rate of arbuscular mycorrhizal was lowest in spring, the colonization rate of arbuscular mycorrhizal was maximal and the spore density significantly declined in summer, the spore density was lowest and colonization rate of arbuscular mycorrhizal declined in fall.Geographical and environmental factors affect the diversity of AM fungi and colonization rate of arbuscular mycorrhiza. The major factors were the temperature, water and soil components. There is significant correlation between both the spore density and the colonization rate, along with the temperature of the soil and the available N and the organic matter in soil.Effects of the clonal plants inbreaking on the diversity of AM fungi and the forming of arbuscular mycorrhizal are different between plant species and sample sites. (1) After Psammochloa villosa inbreaking, the Shannon-Winer index of AM fungi rised from 0.2690 to 0.5566, the spore density and colonization rate significantly increased in Yanjiuzhan. The Shannon-Winer index of AM fungi rised from 0.7227 to 0.9368, the spore density and colonization rate increased in Yulin. (2) After Hedysarum leave inbreaking, the Shannon-Winer index of AM fungi rised from 0.8377 to 1.0308, the spore density and colonization rate of arbuscule significantly increased, but the colonization rate of vesicle significantly descended in Yanjiuzhan. The Shannon-Winer index of AM fungi descended from 1.0338 to 0.9587, the spore density and colonization rate of arbuscule significantly increased, but the colonization rate of hyphae and vesicle significantly descended.The AM fungi in the rhizosphere of Artemisia ordosica significantly accelerated the growth and enhanced the drought-resistance of Artemisia ordosica. After inoculating AM fungi, the number of branchs, fresh and dry weight significantly increased, the moisture status of leaves were improved, the stability of plasma membrane enhanced, activities of some defense enzymes and soluble agar content increased.The results of this thesis enrich the basic theory of desert restoration ecology and provided the scientific basis and germ plasm resource for the applications of AM biotechnology in vegetation restoration and ecology reconstruction of desert.更多还原