溴甲烷甲壤灭菌对大豆苗期根系生长的影响

利用溴甲烷田间土壤灭菌,研究灭菌对正茬、重茬大豆苗期根系生长和产量的影响。试验结果表明,灭菌处理后重茬（连续种植3a）地大豆根系生长良好,根系形态明显改善,总根长、主根长、植株鲜重和根瘤数增加、孢囊线虫孢囊数为0。而灭菌处理后,正葜地大豆根系前期生长受到一定抑制,主根长、总根长、植株鲜重和侧根数有降低的趋势,但随时间推移,抑制幅度降低,溴甲烷处理促进大豆结瘤。灭菌后,重葜大豆与茬大豆根系生长差异减少。溴甲烷灭菌处理可作为克服大豆连作障碍问题措施之一。     

连作障碍与根际微生态研究Ⅲ.土壤酚酸物质及其生物学效应

以黑龙江省大豆重茬 5年与正茬土壤和根系为主要研究对象 ,采用高效液相色谱法 ,研究土壤和根系浸提液中的酚酸物质的含量及其生物学效应 .结果表明 ,重茬土壤中对羟基苯甲酸和香草酸的含量 (1mol·L-1NaOH提取 )大于正茬土壤 ,且差异达到极显著水平 ,香草醛含量差异不显著 ;重茬大豆根系水提液中对羟基苯甲酸、香草酸、阿魏酸、香草醛、香豆素含量均高于正茬 .大豆连作条件下土壤多酚氧化酶活性高于正茬土壤 .重茬大豆根系水提液及在水培条件下外加对羟基苯甲酸对大豆幼苗生长发育有一定的抑制作用 ;酚酸物质加入土壤 1周后 ,对羟基苯甲酸、香草酸、香草醛、阿魏酸、苯甲酸、香豆素残留率分别为 10 .4%、15 .3 %、4.1%、2 .3 %、5 .0 %、17.5 % ;且外加酚酸浓度与土壤中真菌数量呈极显著指数相关 .     

大豆地上部水浸液的化感作用及化感物质的鉴定

研究了重迎茬大豆花荚期植株地上部水浸液及其提取物对大豆种子萌发及幼苗生长的化感作用 ,并鉴定了有明显化感作用组分的物质。结果表明 :与对照组比 ,0 .1 0 g DW/ ml重茬大豆水浸液显著地抑制了大豆胚根生长 ;3 .75× 1 0 - 2g DW/ ml、7.5 0× 1 0 - 2 g DW/ ml正茬、重茬、迎茬大豆水浸液对砂培大豆苗的生长有显著的化感抑制作用 ;重茬、正茬大豆水浸液乙酸乙酯提取的酸性组分、XAD-4树脂提取组分 ,在 0 .6～ 1 .2 g DW/ ml浓度下 ,对大豆种子萌发初期的萌发率及萌发过程中的胚根生长亦表现出显著的化感抑制作用 ;重茬水浸液乙酸乙酯提取的中性、碱性组分在 1 .2 g DW/ ml浓度下 ,对大豆胚根生长有显著抑制作用。上述各组分化感作用大小随组分浓度增加而增加。在相同浓度处理下水浸液及其提取物的化感抑制作用有重茬大于正茬的趋势 ,统计检验差异均不显著。 GC-MS鉴定结果显示 ,正茬、重茬乙酸乙酯酸性组分、XAD-4树脂提取组分中的有机化合物主要是 :丁二酸、苯甲酸、邻羟基苯甲酸、4-羟基苯甲酸、对羟基肉桂酸、2 -甲基苯酚、2 -甲氧基 -4-乙烯基苯酚、间苯三酚、2 -甲基苯甲醛、3 -甲基苯甲醛、5 ,6,7,7a-四氢 -4,4,7a-三甲基 -2 (4 H) -苯并呋喃酮、2 ,4-戊二烯腈等。     

人参皂苷对4种栽培作物早期根系发育的化感效应

人参、西洋参能通过根系分泌三萜皂苷等化感物质,严重影响后茬人参的生长,但对人参以外的植物是否具有化感效应尚不清楚.本实验研究了不同质量浓度的人参皂苷对小麦、白菜、黄瓜及绿豆4种常见栽培作物早期根系发育的影响,结果发现人参皂苷处理液(25、50和100 mg· L-1)对4种作物主根及不定根的发育影响不尽相同.随着处理质量浓度的升高,小麦、白菜、黄瓜根系活力分别比同组CK明显降低,根长、根鲜重也呈降低趋势.各浓度人参皂苷处理对黄瓜和绿豆下胚轴不定根的数量、根长、根鲜重及根系活力的影响均未达到显著水平,但二者抗氧化酶的活性都微有升高.总之,人参皂苷对4种栽培作物的主根发育均有抑制作用,尤其对小麦、黄瓜主根生长的抑制作用较强;但对黄瓜和绿豆不定根发育的影响不明显.     

菊花不同部位及根际土壤水浸液对其扦插苗生长的自毒效应

以自毒性较强的菊花品种 '高压太子' 插穗为材料,调查了菊花枯落物、叶、茎、根系和根际土壤水浸液处理对其扦插苗生长和生理指标的影响,以探讨菊花自毒作用机制.结果表明,菊花不同部位水浸液处理对其扦插生根的根长、鲜重及根数均有抑制作用,并以叶和枯落物水浸液对根长的抑制作用最强,且均达到极显著水平;随水浸液浓度的升高,其对扦插苗根长、鲜重及根数的抑制作用越明显.水浸液处理导致扦插苗叶片可溶性糖、可溶性蛋白和叶绿素含量显著下降,显著抑制根系脱氢酶与叶片硝酸还原酶活性.可见,菊花地上部和根际土水浸液可能通过抑制其扦插苗根系脱氢酶与叶片硝酸还原酶活性,降低叶片叶绿素、可溶性糖和可溶性蛋白的含量,在营养水平上抑制不定根的形成而产生明显的自毒效应,且该自毒作用表现出明显的浓度梯度效应和部位差异.     

甾类激素炔雌醇、炔诺酮和左炔诺孕酮对拟南芥根生长的影响

采用不同浓度的人工合成甾类激素炔雌醇、炔诺酮和左炔诺孕酮处理拟南芥幼苗,研究3种激素对其根生长和根中内源激素含量的影响.结果表明:(1)30μg?L-1炔雌醇处理显著促进主根的伸长、侧根数及侧根总长的增加,促进主根根毛数和地下部鲜重的增加,增大内源IAA和iPAs含量,以及IAA/iPAs比值;3 000μg?L-1炔雌醇处理则增加主根的弯曲度;(2)炔诺酮活性相对较弱,浓度为300μg?L-1时对主根长、侧根数、侧根总长的促进效果最大,IAA含量增加而iPAs含量降低,IAA/iPAs比值最大;3 000μg?L-1炔诺酮则引起主根弯曲,抑制根毛的生长,但促进侧根数和的地下部鲜重的增加;(3)左炔诺孕酮的活性较高,3μg?L-1时对拟南芥主根长、主根根毛数增加最为显著;300μg?L-1时对侧根数、根毛密度的增幅最大,IAA含量增加,IAA/iPAs比值最大;3 000μg?L-1时显著抑制主根的生长和侧根的生成.     

人参皂苷对4种栽培作物早期根系发育的化感效应

人参、西洋参能通过根系分泌三萜皂苷等化感物质,严重影响后茬人参的生长,但对人参以外的植物是否具有化感效应尚不清楚。本实验研究了不同质量浓度的人参皂苷对小麦、白菜、黄瓜及绿豆4种常见栽培作物早期根系发育的影响,结果发现人参皂苷处理液（25、50和100mg·L-1）对4种作物主根及不定根的发育影响不尽相同。随着处理质量浓度的升高,小麦、白菜、黄瓜根系活力分别比同组CK明显降低,根长、根鲜重也呈降低趋势。各浓度人参皂苷处理对黄瓜和绿豆下胚轴不定根的数量、根长、根鲜重及根系活力的影响均未达到显著水平,但二者抗氧化酶的活性都微有升高。总之,人参皂苷对4种栽培作物的主根发育均有抑制作用,尤其对小麦、黄瓜主根生长的抑制作用较强;但对黄瓜和绿豆不定根发育的影响不明显。     

桑树/大豆间作对植物生长及根际土壤微生物数量和酶活性的影响

利用根系分隔试验的方法,研究了桑树/大豆间作体系中植株生长、根际土壤酶和土壤微生物的变化.结果表明： 根系不分隔处理的桑树和大豆的株高、叶片数、根长和根冠比等生长指标均高于塑料膜分隔和尼龙网分隔处理,大豆有效根瘤数较多.不分隔、尼龙网分隔处理的桑树和大豆的根际土壤磷含量比塑料膜分隔分别高10.3%、11.1%和5.1%、4.6%.不分隔和尼龙网分隔处理的桑树和大豆根际微生物数量、微生物多样性和土壤酶活性均高于塑料膜分隔处理.表明桑树和大豆间作具有明显的种间促进效应.     

土壤灭菌对辣椒抗连作障碍效果

采用土壤灭菌的方法研究了生物因素对连作3年的辣椒植株生长发育和抗氧化酶活性的影响。探讨了土壤灭菌对辣椒抗连作障碍的效果。结果表明,灭菌的连作土壤,辣椒的株高、茎粗、叶面积、叶绿素含量、地上部鲜重、根鲜重、根系活力等值均高于未灭菌土壤,并伴随着抗氧化酶如超氧化物歧化酶（SOD）和过氧化物酶（POD）的活性降低。说明土壤灭菌提高了地上部和根的健壮程度．降低了连作辣椒中抗氧化酶的活性。与正茬土壤相比,辣椒植株的健壮程度仍存在明显差异,抗氧化酶SOD和POD的活性偏高,这可能是短期连作中,土壤灭菌有效的克服了有害微生物的连作障碍效应,但是不能消除由化感物质引起的连作障碍效应。     

狗牙根营养繁殖体对模拟水淹的生物学响应

研究了水淹条件下狗牙根(Cynodon daetylon)繁殖体的形态特征和生物量的变化及其水淹后的恢复状况.结果表明,水淹深度的增加会诱导植株茎快速增高,而叶片数则明显下降.水淹时间对植株叶片数、茎直径、茎与根长比的影响显著,而对分枝数、茎长、根长、茎节数不显著.植株地上部生物量和总生物量随着水淹时间的延长而显著减少,但地下部生物量的变化不显著.所有实验处理的植株水淹后都能存活且恢复生长.但水淹对恢复期植株的生长仍有影响,植株的茎长、根长、分枝数、直径、叶片数、叶长、宽度以及叶的长宽比都随水淹时间的延长而显著减少,但茎节数与叶片数的差异不显著.根、茎、叶生物量和植株总生物量也随着水淹时间的延长而减少.实验表明狗牙根繁殖体通过延长茎长、改变叶形和减少生物量等方式对水淹显示出较强的耐受能力.     

Effects of soil sterilization,inoculation with vesicular-arbuscular mycorrhizal fungi and cropping history on peanut (Arachis hypogaea L.) growth in an oxisol from subtropical Australia

The effects of soil sterilization and inoculation with vesicular-arbuscular mycorrhizal fungi (VAMF) on VAMF colonization, nutrition and growth of peanut plants (cv. Virginia Bunch) were investigated in an Oxisol soil in pots in the glasshouse. Sterilization, nutrient and inoculation treatments were applied to soil with a history of either continuous summer cropping (>50 years) or continuous grass pasture. Root colonization by VAMF was strongly affected by sterilization of soil from both cropping histories. Irradiation and aerated steam treatments virtually eliminated VAMF colonization; methyl bromide+chloropicrin caused an early reduction in colonization which was no longer visible twenty-one days after flowering; and DD+methyl isothiocyanate caused no significant reduction. Despite earlier differences in VAMF colonization of roots, plant growth responses were not recorded until after flowering. Plant growth 21 days after flowering was strongly correlated with VAMF colonization at first flower and at 21 days after first flower. Effective soil sterilization caused significant reductions in plant growth which were eliminated by addition of VAMF inoculum. Growth reductions in the absence of VAMF could be directly related to severe P deficiency, which was reflected in P uptake as early as first flower; Zn uptake was also reduced. Although VAMF colonization was slightly higher in grassland than in continuously cropped soil, growth responses to VAMF inoculation were not observed in unsterilized soil regardless of cropping history, indicating a general adequacy of resident VAMF populations. Plants grew better in untreated cropped soil than in grassland soil although growth was poor in both after effective soil sterilization. These differences could be related to the higher level of available P in the cropped soil and the inability of plants to access this P in the absence of VAMF. Regular applications of N-free nutrient solution had no effect on plant growth even in effectively sterilized soil, suggesting a threshold response to P in the absence of VAMF in this soil.     

连作大豆植株化感作用的模拟研究

使用组培技术在无菌条件下研究了大豆根系分泌物和大豆组织水浸液对大豆苗的化感作用。结果表明,大豆根系分泌物和大豆组织水浸液对“下茬”大豆苗的生长和某些生理活性均有显着影响。这种影响与大豆苗生长激素代谢紊乱有关。从根系分泌物和植株水浸液中均分离出了已知酚酸类化感物质香草酸、香草醛和对羟基苯甲酸。这类物质的影响对大豆连作障碍有直接关系.     

连作大豆根分泌物对根腐病病原菌的化感作用

采用砂培,水培和室内培养等试验方法研究了连作大豆根分泌物对根腐病病原菌的化感作用。结果表明,与对照相比,连作和轮作大豆根分泌物对半镰孢菌,粉红粘帚功和尖镰孢菌尤其是对半裸镰孢菌的生长有明显的化感促进作用,差异达显著或极显著水平,低浓度时,连作大豆根分泌物对半裸镰孢菌和粉红粘帚菌生长的化感促进作用明显大于轮作大豆,差异达显著水平,同一茬口,高浓度根分泌物半裸镰孢菌生长的化感促进作用小于低浓度,而且在连作大豆中差异达显著水平。与对照相比,高浓度的邻苯二甲酸和丙二酸（L5和B5）对半裸镰孢菌,粉红粘帚菌和尖镰孢菌尤其是对半裸镰孢菌的生长有化感抑制作用,差异达显著或极显著水平,而低浓诬的邻苯二甲酸和丙二酸对半裸镰孢菌,粉红粘帚菌和尖镰孢菌的生长有化感促进,部分差异达显著水平。     

连作障碍因素对大豆养分吸收和固氮作用的影响

采用分室装置,利用不同孔径的膜研究大豆连作条件下,化感物质、土壤有害生物和大豆胞囊线虫等因素不断累加对植株生长、生物固氮作用和矿质养分吸收和分配的影响。结果表明,随着各因素不断累加,植株的地上部、根系和根瘤干重逐渐降低;除Ca元素外,植株组织的P、K等矿质元素单位含量下降,吸收总量下降,地上部分配的养分比例下降。在化感物质和土壤有害生物因素的基础上接种线虫,对生物固氮和矿质养 分的吸收和分配影响明显。     

大豆连作障碍研究 Ⅱ. 大豆连作减产机理及对土壤紫青霉菌毒素的调控对策

研究分析了土壤紫青霉菌分泌毒素对连作大豆全生育过程的危害。结果表明,在大豆种子萌动期毒素致毒作用已经开始; 在大豆幼苗期及分枝期,较高浓度毒素(×10³倍稀释)使大豆完全不结瘤,极低浓度(×10⁵倍稀释)仍然抑制40%结瘤,致使重茬大豆光合固氮能力显着降低。而大豆残根、凋落物等通过刺激紫青霉菌的增长,造成对大豆进一步的危害。对连作大豆土壤紫青霉毒素的调控研究表明,使用土壤放线菌MB生物防治,可使重茬大豆增产8.4～18.9%; 使用海洋放线菌MB-97生物防治可使重茬大豆增产30.5%. 应用MB97制剂对连作大豆全生育过程的防病、减毒控制的综合调控,可使重茬5年大豆田间微区试验折合大豆产量达到4575kg·hm^-2.     

Analysis of interspecific relationships between Funneliformis mosseae and Fusarium oxysporum in the continuous cropping of soybean rhizosphere soil during the branching period

This study analysed the interspecific relationships between the dominant arbuscular mycorrhizal (AM) fungus, Funneliformis mosseae, and the major soybean root rot pathogen, Fusarium oxysporum, in the rhizosphere soil of continuous cropped soybean. Our aim was to provide theoretical evidence on the AM fungi to overcome the obstacles of soybean continuous cropping. We selected soybean cultivars, including Kenfeng 16 (an intermediate cultivar), Heinong 44 (a high-fat cultivar) and Heinong 48 (a high-protein cultivar), and sowed in the soybean continuous cropping soil under different treatments. The infection status of the soybean roots during the branching period by Fu. mosseae and F. oxysporum was estimated using the standard polymerase chain reaction method, as well as their colonisation status in rhizosphere soil. The AM fungal colonisation rates and F. oxysporum disease incidence of soybean roots were determined, respectively. Quantitative polymerase chain reaction was applied to analyse the DNA content of Fu. mosseae and F. oxysporum to investigate the relationship between Fu. mosseae and F. oxysporum. The results show that both Fu. mosseae and F. oxysporum can infect the soybean roots during the branching period and colonise the rhizosphere. However, the DNA content of F. oxysporum clearly decreased in soybean root and rhizosphere samples after the inoculation with Fu. mosseae. In addition, the disease incidence of F. oxysporum significantly decreased after inoculation with Fu. mosseae, which might indicate inhibitive effects of Fu. mosseae over F. oxysporum.     

Diversity of Rhizosphere Soil Arbuscular Mycorrhizal Fungi in Various Soybean Cultivars under Different Continuous Cropping Regimes

Recent studies have shown that continuous cropping in soybean causes substantial changes to the microbial community in rhizosphere soil. In this study, we investigated the effects of continuous cropping for various time periods on the diversity of rhizosphere soil arbuscular mycorrhizal (AM) fungi in various soybean cultivars at the branching stage. The soybean cultivars Heinong 37 (an intermediate cultivar), Heinong 44 (a high-fat cultivar) and Heinong 48 (a high-protein cultivar) were seeded in a field and continuously cropped for two or three years. We analyzed the diversity of rhizosphere soil AM fungi of these soybean plants at the branching stage using morphological and denaturing gradient gel electrophoresis (DGGE) techniques. The clustering analysis of unweighted pair-group method with arithmetic averages (UPGMA) was then used to investigate the AM fungal community shifts. The results showed that increasing the number of years of continuous cropping can improve the colonization rate of AM fungi in different soybean cultivars at the branching stage. The dominant AM fungi in the experimental fields were Funneliformismosseae and Glomus spp. The number of years of continuous cropping and the soybean cultivar both had obvious effects on the diversity of AM fungi, which was consistent with the results of colonization rate analysis. This study establishes a basis for screening dominant AM fungi of soybean. In addition, the results of this study may be useful for the development of AM fungal inoculants.     

摩西管柄囊霉Funneliformis mosseae对连作大豆分枝期根系AM真菌群落结构的影响

本文研究摩西管柄囊霉Funneliformis mosseae对短期连作3个大豆品种分枝期根系AM真菌群落结构的影响,旨在探索不同大豆品种与AM真菌在连作土壤中的互作效应。通过向黑农44（HN44）、黑农48（HN48）和恳丰16（KF16）3个大豆品种盆栽土壤中接种F. mosseae,对接菌连作0年（未连作对照组）、连作1年、连作2年土壤中的大豆根系,采用Nested-Program Control Register-DGGE技术分析。结果表明,接种F. mosseae后,不同大豆品种根系AM真菌多样性指数和丰度值表现为连作2年的土壤>连作1年的土壤>未连作的土壤;其中,球囊霉属Glomus和F. mosseae为3个大豆品种根系中AM真菌的优势菌群。接种F. mosseae对连作1年、连作2年3个大豆品种根系AM真菌群落结构具有显著影响。