水分胁迫条件下接种菌根对玉米抗旱性的影响

采用土培试验研究了水分胁迫条件下接种菌根对玉米生长发育、光合作用、养分吸收和水分利用的影响。结果表明：土壤干旱使植株地上部及根系的生长量比对照显著下降，植株的形态发育受到抑制；接种VA菌根菌的植株体内磷营养状况得到改善，提高了土壤磷的有效利用率。接种菌根减轻了水分胁迫对植株生长的抑制程度，提高了植株叶片光合强度，增加了干物质积累。试验结果表明，菌根可以改善植株的水分状况，使叶片相对含水量增加，复水试验表明菌根植物比非菌根植林从干旱逆境中恢复水分的速度要快得多，同时也提高了植株水分利用效率。     

A semiaxenic phototrophic system to study interactions between arbuscular mycorrhizal and pathogenic fungi in woody plants

Among other benefits, arbuscular mycorrhizal (AM) fungi may increase plant tolerance to root diseases. The research on the underlying mechanisms requires growth conditions that are both controlled and realistic. To study these interactions, a semiaxenic phototrophic system was developed in which the roots grow in a controlled environment and can be inoculated with both pathogenic and symbiotic fungi. Micropropagated fig plantlets were grown in containers having shoots in the outside and roots in a growth medium without sugar, inoculated or not with the AM fungus Rhizophagus irregularis and the pathogenic fungus Armillaria mellea. Dual inoculated plants developed the mycorrhizal association and pathogen infection symptoms. Mycorrhizal inoculation lowered disease index and increased plant growth. Colonization of A. mellea in fig roots was quantified by real-time PCR, showing that R. irregularis did not significantly lower the quantity of Armillaria, suggesting that other mechanisms were involved in increased tolerance to the pathogen. The results show that the system proposed is suitable to study the triple interaction involving plant, AM and root pathogenic fungi.     

梭梭根系的水分再分配特征对其生理和形态的影响

采用上下分根方法及根系观测技术,设置控制处理(仅接受白天自然光照),夜间光照处理(接受24 h光照),加水及夜间光照处理(接受24 h光照+加水),对梭梭根系是否存在水分再分配作用进行了验证,在此基础之上,进一步研究了水分再分配对梭梭生理和形态的影响。结果表明:(1)控制处理梭梭黎明前及正午同化枝水势高于夜间光照处理,且控制处理和加水及夜间光照处理梭梭上管部分根水势也较夜间光照处理高,说明夜间弱蒸腾作用下,控制处理的梭梭发生了水分再分配作用。(2)水分再分配作用促进梭梭蒸腾及光合作用,控制处理与加水及夜间光照处理的梭梭蒸腾速率均大于夜间光照处理,且控制处理和加水及夜间光照处理的梭梭最大净光合速率也较夜间光照处理高。(3)控制处理与加水及夜间光照处理梭梭地上部分生物量显著高于夜间光照处理,不同处理的梭梭地下部分总生物量、上管地下部分生物量及上管比根长的关系为:加水及夜间光照处理控制处理夜间光照处理。梭梭具有水分再分配作用,在夜间弱蒸腾条件下,根系吸收下层湿润土壤中的水分并释放至上层干燥土壤中,以缓解干旱环境下植物的水分亏缺,水分再分配作用可促进植物蒸腾及光合作用,增加植物的根冠比和根系碳分配。     

干旱胁迫下AMF对多枝柽柳幼苗和疏叶骆驼刺根系生长和氮素吸收分配的影响

丛枝菌根真菌(Arbuscular Mycorrhizal Fungi,AMF)对植物抗旱、养分吸收等有重要作用,但在特定环境胁迫下不同生活型植物对AMF的响应存在差异.本文以塔里木河下游荒漠河岸林的优势灌木多枝柽柳(Tamarix ra-mosissima)和常见半灌木疏叶骆驼刺(Alhagi sparsifolia...     

Arbuscular mycorrhizal fungi improved plant growth and nutrient acquisition of desert ephemeral Plantago minuta under variable soil water conditions

Desert ephemeral plants play an important role in desert ecosystem.Soil water availability is considered as the major restrictive factor limiting the growth of ephemeral plants.Moreover,arbuscular mycorrhizal fungi(AM fungi) are widely reported to improve the growth of desert ephemerals.The present study aimed to test the hypothesis of that AM fungi could alleviate drought stress of desert ephemeral Plantago minuta,and AM fungal functions reduced with the improvement of soil water content.A pot experiment was carried out with three levels of soil water contents(4.5%,9.0%,and 15.8%(w/w)),and three AM inoculation treatments(Glomus mosseae,Glomus etunicatum and non-inoculation).The results indicate that mycorrhizal colonization rate decreased with the increase of soil water availability.Inoculation improved plant growth and N,P and K acquisition in both shoots and roots regardless water treatments.When comparing the two fungi,plants inoculated with G.mosseae performed better than those inoculated with G.etunicatum in terms of plant growth and nutrient acquisition.These results showed that ameliorative soil water did not suppress arbuscular mycorrhizal fungal functions in improving growth and nutrient acquisition of desert ephemeral Plantago minuta.     

荒漠河岸林地区胡杨幼苗根系水力提升作用探究

植物水力提升作用是指低蒸腾条件下处于湿润区域根系吸水后运输到干燥区,并将水分释放到根际周围的干土中的现象。通过上下层分根试验法,研究生长季胡杨幼苗的根系提水作用。结果表明：① 与成年胡杨相似,胡杨幼苗根系存在水力提升作用;② 幼苗的水力提升作用发生在21:00 时至次日6:00时 ,生长季3株胡杨幼苗的总提水量分别为2.78 kg,2.31 kg和2.46 kg,日均提水量为0.022 6 kg,0.018 7 kg和0.02 0 kg;③ 3株胡杨幼苗的日均提水量占上层土壤蒸发量的13%~20%,在植物蒸腾作用明显的7~8月,日均提水量也较大;④ 下层土壤的根系生物量和提水量相关性显著。     

施肥、刈割和土壤镇压对鸭茅丛枝菌根形成的影响

施磷肥、强度刈割和土壤镇压都能显著降低鸭茅(Dactylis glomerata L.)的菌根形成。磷肥增加土壤有效磷浓度,而刈割减少根系生长和光合产物向根部的分配,土壤镇压则减少土壤空气、孔隙和根系生长,这些都不利于菌根形成。施肥、刈割和土壤镇压的交互作用对菌根形成的影响相对较小。     

西部矿区接菌对风化煤与黄土配比的土壤改良效应

针对西部矿区土壤贫瘠、有效养分缺乏和作物难以生长的现状,采用盆栽试验方法,风化煤与黄土按不同配比混合为供试基质,玉米为供试植物,研究接种丛枝菌根真菌对玉米生长的影响及其对不同混合基质的改良效应,寻求风化煤与黄土最佳配比。结果表明:接种丛枝菌根真菌促进了玉米的生长和对矿质元素的吸收,在风化煤与黄土质量比(1∶1)时菌根生态效应达到最大,玉米干质量、叶色值、地上部分氮磷钾累积量分别达到4.61 g·株~(-1),41.17,53.01 mg·株~(-1),7.15 mg·株~(-1),79.42 mg·株~(-1);风化煤与黄土(1∶1)处理菌丝密度达到4.91 m·g~(~(-1)),且玉米根系侵染率达到最大。随着风化煤比例的增加,根际土壤中球囊霉素相关蛋白和酸性磷酸酶活性逐渐递增。丛枝菌根与风化煤的协同作用促进了作物的生长,改善了根际土壤微环境,实现了对沟壑区土壤的改良和培肥。     

AM真菌与西瓜枯萎病关系初探

 在温室盆栽条件下研究了丛枝菌根(Arbuscular Mycorrhiza,AM)真菌Gigaspora rosea Nicol.& Schenck、Glomusmosseae(Nicol.& Gerd.) Gerdemann & Trappe和Glomus versiforme(Karsten) Berch与西瓜枯萎病菌(Fusariumoxysporum f. sp. niveum)的关系。结果表明,接种AM真菌能促进西瓜植株的生长发育,增加植株干重;显著减少根内和根围土壤中镰刀菌群体数量及其对根系的侵染率;降低枯萎病发病率和病情指数,从而减轻西瓜枯萎病的危害。接种F.oxysporum f. sp. niveum能降低AM真菌对西瓜的侵染率,并且AM真菌与镰刀菌的不同接种时间和顺序影响西瓜枯萎病的发生发展,证实AM真菌与镰刀菌存在竞争关系。另外,AM真菌对西瓜高感枯萎病品种的防治效果优于抗病品种,说明高感品种对菌根的依赖性较大。     

局部高浓度硝酸盐供应对玉米根系 形态及氮累积的影响

以郑单958和鲁单981为研究对象,进行水培分根试验,在正常供水和水分胁迫条件下,分别以均匀低浓度硝酸盐处理主根和种子根(LPR-LSR)、局部高浓度硝酸盐处理主根（HPR-LSR）和局部高浓度硝酸盐处理种子根（LPR-HSR）,测定分析根系形态、生物量以及氮含量。结果表明：与氮低效鲁单981相比,氮高效郑单958具有较高的主根根长、根表面积、根系生物量、地上部生物量和氮累积量。水分胁迫条件下,郑单958和鲁单981的主根的根长、根表面积、根体积、地上部生物量和氮累积量总体上均低于正常水分条件。玉米主根和种子根对局部高浓度硝酸盐的反应存在差异。与均匀低浓度硝酸盐处理相比,局部高浓度硝酸盐处理促进正常水分条件下主根和种子根根系的生长,尤其是根长和根系表面积;在正常水分条件下,主根根长和根系表面积增加幅度范围为6.8%~27.3%和1.9%~21.9%,除HPR-LSR处理条件下的郑单958外,种子根根长和根系表面积增加幅度范围为30.4%~92.7%和10.5%~135.1%;在水分胁迫条件下,主根根长和表面积增加幅度范围为24.6%~152.9%和62.1%~229.9%,然而种子根根长降低了10.0%~29.9%,表明水分胁迫会影响种子根对高浓度硝酸盐的响应。除水分胁迫条件下LPR-HSR处理外,局部高浓度处理可同时增加两侧根系的生物量和氮累积量。无论是正常供水还是水分胁迫,与LPR-LSR处理相比,局部高浓度硝酸盐供应均能够增加地上部生物量以及氮累积量,在LPR-HSR处理条件下,增加幅度范围分别在35.0% ~107.9%和162.9%~291.1%,在HPR-LSR处理条件下分别为56.7%~109.4%和204.1%~377.0%,HPR-LSR处理条件下增加幅度较大,表明在氮素非均匀分布环境中,当主根处于高浓度硝酸盐区域时将会更显著促进生物量的增加和氮累积。     

Evaluation of a polyclonal antibody immunoassay for detection and quantification of Macrophomina phaseolina

Detection and quantification of Macrophomina phaseolina , causal agent of charcoal/dry root rot disease in many crop plants, was carried out using the ELISA serological technique. Polyclonal antisera raised to water soluble extracts of mycelium, the residual water insoluble mycelial materials or ribosomal proteins were evaluated for specificity and cross-reactivity with 16 common soil fungi by ODD and DAS–ELISA. Soluble and cell wall antisera exhibited strong cross-reactivity with most of the fungal isolates. Ribosomal antibodies were less reactive to common soil fungi except Fusarium oxysporum f.sp. ciceri . Mycelial antigens of M. phaseolina on chickpea roots were detectable with DAS–ELISA at a minimum concentration of 10 ng g⁻¹ at 1 : 100 root : buffer dilution. Quantitative estimation of M. phaseolina on roots was evaluated by ELISA under different temperatures and moisture conditions, and in soil amended with a potential antagonist ( Trichoderma harzianum 25-92). A significant reduction in ELISA values was observed in T. harzianum -amended treatments. This method may be useful for detection and rapid screening of M. phaseolina under different environmental conditions.     

覆盖处理苹果细根分布与土壤物理性状响应关系研究

以12年生红富士苹果树为试材,研究黄土高原旱塬区不同覆盖措施(覆膜、覆草、覆沙)对苹果细根(直径≤2 mm)及土壤性状的影响。结果表明:地表覆盖可有效降低土壤容重,增大土壤含水量及孔隙度,增加细根数量,增大根系吸收水肥效率。覆膜处理细根水平分布范围与清耕(CK)相似,在距干0~90 cm范围内,垂直密集分布最大深度由CK的60 cm提升至40 cm,36.05%的细根分布在0~20 cm土壤表层。与CK相比,覆草、覆沙处理的细根水平分布范围由90 cm扩展至120 cm,垂直均匀分布整个土壤剖面,利于树体对深层土壤水肥的吸收利用。土壤物理性状与细根根长、表面积、根长密度呈极显著相关,覆膜处理中根径与比根长也与土壤物理性状表现出相关性。综合分析根系分布与土壤物理性状,覆草处理是陇东旱塬区苹果园较为适宜的地表覆盖模式。     

Arbuscular Mycorrhizal Fungi Alleviate the Negative Effect of Temperature Stress in Millet Lines with Contrasting Soil Aggregation Potential

Arbuscular mycorrhizal fungi (AMF) establish a mutualistic symbiosis with several plants and play a key role in improving plant growth, tolerance to abiotic and biotic stresses as well as the soil structure. This work aimed at elucidating the AMF temperature stress modulating impact on four pearl millet lines plant growth and soil aggregation. Experimental trials were carried out in both greenhouse and growth chamber to determine the response of the four millet lines to inoculation with two AMF strains (Rhizophagus aggregatus and Funneliformis mosseae) under heat and non-stress conditions. We first investigated the mycorrhizal colonization (MC) and the mycorrhizal growth response (MGR) of millet lines in relation with their soil aggregation potential (root adhering soil/root biomass, MAS/RB) in the greenhouse. Secondly, the four millet lines were grown in two separated growth chambers and subjected to a day/night temperature of 32/28?°C as the control treatment and 37/32?°C as the temperature stress treatment. Plant growth, mycorrhization rate and several physiological, mycorrhizal and soil parameters were measured. Results showed that the mycorrhization rates of millet lines were low and not significantly different. Funneliformis mosseae (31.39%) showed higher root colonization than Rhizophagus aggregatus (22.79%) and control (9.79%). The temperature stress reduced the mycorrhizal colonization rate, shoot and root biomass, and the soil aggregation for all tested lines. L220 and L132 showed more MC rate and MGR than the other lines under control and high-temperature treatment. The MGR was significantly better under temperature stress conditions than in the control. Under the temperature stress conditions, inoculation with R. aggregatus and F. mosseae increased chlorophyll concentration, root dry weight and shoot dry weight as compared to non-inoculated plants. AMF inoculation, particularly with F. mosseae had a positive influence on the tolerance of millet lines to temperature stress. This study demonstrates that AMF play an important role in the response of these four millet lines to temperature stress. AMF is therefore an important component in the adaptation of crops to climatic variations in Sub-Saharan Africa.

     

The influence of water level and nutrient availability on growth and root system development of Myriophyllum aquaticum

Myriophyllum aquaticum is an aquatic plant of still or slow flowing waters. The species mostly occurs in its emerged growth form in dense stands, but submerged shoots can also be found. Due to its rapid growth, M. aquaticum is considered one of the most important aquatic weeds worldwide. In southern Europe, M. aquaticum occurs in irrigation and drainage systems, rice fields and lowland wetlands. In this study, root development and growth response of M. aquaticum to different water levels and nutrient availabilities were investigated in a rhizotron experiment under Central European climatic conditions. The species shows an ability to respond to drained soil conditions by a rapid root growth (up to >1 cm day⁻¹), resulting in a deep root system under drained conditions. In waterlogged soil, the root system spreads more horizontally. Root density increased with increasing nutrient availability. Root:shoot ratio increased significantly with decreasing nutrient availability. In addition, total shoot length, shoot biomass, root biomass and total biomass differed significantly between different water levels and different nutrient availabilities. Relative growth rate increased with increasing water level and nutrient availability. Shoot porosity was higher in nutrient rich substrate than in nutrient low substrate. Root porosity increased with increasing water level. In conclusion, M. aquaticum shows a high tolerance to different water levels, which may be important for future habitat conditions in waterbodies and wetlands in Central Europe under the impact of global change with increased water level fluctuations.     

滴灌条件下根区水分对春小麦根系分布特征及产量的影响

通过小区滴灌根区水分控制试验,研究亏缺、丰水、适水不同水分处理对春小麦根系特征的垂直分布、产量构成和水分利用效率等的影响.结果表明,孕穗-扬花是滴灌春小麦根系生长的关键时期,其根系主要分布在0～40 cm土层,根长密度和根干重在土壤剖面上的分布呈y=A×e-Bx的负指数递减趋势.不同根区水分对春小麦根系生长及分布有显著...     

Uptake, translocation and phytotoxicity of root-absorbed haloxyfop in soybean, Festuca rubra L. and Festuca arundinacea Schreb

The concentrations of haloxyfop in nutrient solution required to reduce the total plant dry weight of soybean (Glycine max L. Merr. ‘Evans’), red fescue (Festuca rubra L. ‘Pennlawn’), and tall fescue (Festuca arundinacea Schreb. ‘Houndog’) by 50% (GR₅₀) were determined. The GR₅₀) values for soybean, red fescue and tall fescue were 76 μM, 3μM and 0.4 μM, respectively. The reduction in growth in roots and shoots of soybean was similar. In contrast, the relative reduction in root tissue weight was greater than that for foliar tissue in both grass species. The amount of ¹⁴C-haloxyfop in soybean roots or shoots was higher than in red fescue or tall fescue. Red fescue accumulated less haloxyfop in the foliage than in the roots. On the other hand, similar amounts of ¹⁴C-haloxyfop accumulated in both organs in both soybean and tall fescue. ¹⁴C-haloxyfop appeared to be actively absorbed by the roots of all species. Soybean absorbed more nutrient solution, but utilized it less on a per gram dry matter produced basis than the grass species. Differences in the uptake and translocation of haloxyfop by roots do not account for differences in tolerance between species. However, a higher level of retention of haloxyfop in the roots of red fescue than in tall fescue may provide the former with an additional selectivity advantage under conditions where there is significant root exposure to the herbicide.     

Effects of climatic factors on native arbuscular mycorrhizae and Meloidogyne exigua in a Brazilian rubber tree (Hevea brasiliensis) plantation

The root-knot nematode Meloidogyne exigua and arbuscular mycorrhizal (AM) fungi may both occur in the roots of Brazilian rubber trees ( Hevea brasiliensis ). AM fungi may stimulate plant growth whereas nematodes usually reduce it. Variations of native AM fungi and M. exigua populations in soil and roots of rubber trees were studied for one year in a Brazilian plantation. The number of AM spores in the soil was generally greater in the rainy season than in the dry season, although AM colonization of roots was unaffected by season. During the dry season, numbers of juveniles and eggs of M. exigua in roots were lower than in the rainy season. A site without nematodes in the soil or roots showed the greatest numbers of AM spores in soil and highest AM colonization of roots. A negative correlation was observed between the percentage of AM colonization and the number of second-stage juveniles in soil and second-stage juveniles and eggs in roots. Microscope observations revealed (i) tissue specificity for each of the microorganisms in the roots, with a cortical location of mycorrhizae and a mainly vascular cylinder location of nematodes, and (ii) that Gigaspora was the most abundant AM genus in the plantation soil.     

拮抗内生细菌Bacillus mojavensisZA1在马铃薯根内及根际的定殖动态及其对土壤微生物的影响

利用GFP标记和平板分离法研究了拮抗内生细菌Bacillus mojavensisZA1在马铃薯根内及根际的定殖动态及其对土著微生物的影响。结果表明,标记菌株ZA1-gfp在土壤中定殖数量为3.7×10⁴~7.3×10⁴cfu/g;马铃薯根际为3.0×10³~1.5×10⁵cfu/g,根内为49~630cfu/g;马铃薯的根部横切面、根毛和根表皮等部位均观察到发绿色荧光的菌株ZA1-gfp菌体或聚集菌落。利用灌根法施入生防菌后,土壤中细菌、放射菌数量显著增加(P<0.05),土壤真菌数量在中期下降;土壤中细菌、真菌和放线菌的数量分别在相对稳定范围内(数据之间差异不显著)消长。该结果说明菌株ZA1-gfp能够在马铃薯根内及根际定殖且不影响土壤中土著微生物的群落稳定性。     

摩西球囊霉对紫花苜蓿烟色织孢霉根腐病的影响

紫花苜蓿Medicago sativa是一种优质的多年生豆科牧草,素有"牧草之王"的美称。根腐病是紫花苜蓿生产中的主要限制因素,可抑制植物生长,严重时导致植物死亡,造成巨大的经济损失。丛枝菌根真菌（Arbuscular mycorrhizal fungi,AM）广泛存在于农业系统中,可与植物根系形成内生菌根,提高宿主植物对营养元素和水分的吸收,增加植物产量和抗逆性。本研究以紫花苜蓿为试验材料,探究接种AM真菌摩西球囊霉Glomus mosseae对紫花苜蓿根腐病烟色织孢霉Microdochium tabacinum的影响。结果表明,摩西球囊霉可抑制烟色织孢霉的侵染,植株发病率降低了20.78%;病原菌的侵染显著抑制紫花苜蓿根系生长和养分吸收,植物地下生物量降低12.87%,根长降低20.52%,根系P含量降低了18.29%,丙二醛（MDA）含量提高了12.78%;AM真菌可以缓解病原菌的危害,促进紫花苜蓿生长,与不接种AM真菌的处理相比,地上生物量、地下生物量、根长分别提高了47.77%,38.67%和20.67%;防御酶超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性分别提高了42.25%、26.05%和33.62%;地上部分和地下部分P含量分别提高了58.63%和75.38%。     

Optimal root system strategies for desert phreatophytic seedlings in the search for groundwater

Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap. seedlings were studied across a gradient of groundwater depths. Leaves, stems and roots of different orders were measured after 120 days of different groundwater treatments. Results indicated that the depth of soil wetting front and the vertical distribution of soil water contents were highly controlled by groundwater depths. The shoot growth and biomass of A. sparsifolia decreased, but the root growth and rooting depth increased under deeper groundwater conditions. The higher ratios of root biomass, root/shoot and root length/leaf area under deeper groundwater conditions implied that seedlings of A. sparsifolia economized carbon cost on their shoot growths. The roots of A. sparsifolia distributed evenly around the soil wetting fronts under deeper groundwater conditions. Root diameters and root lengths of all orders were correlated with soil water availabilities both within and among treatments. Seedlings of A. sparsifolia produced finer first- and second-order roots but larger third- and fourth-order roots in dry soils. The results demonstrated that the root systems of desert phreatophytes can be optimized to acquire groundwater resources and maximize seedling growth by balancing the costs of carbon gain.