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.     

大蒜根系分泌物对不同受体蔬菜的化感作用

利用组织培养技术,在无菌条件下研究大蒜根系分泌物对莴苣、辣椒、萝卜、黄瓜、白菜和番茄等蔬菜作物的化感作用.结果表明：大蒜根系分泌物对6种蔬菜作物的发芽率、发芽指数、苗高及保护酶活性没有影响;对根长、地上部鲜质量及根鲜质量略有促进作用,其中,莴苣与对照差异达显著水平,化感效应指数分别为+0.163、+0.106、+0.318,白菜根长与对照差异达显著水平,化感效应指数为+0.120,其它受试作物与对照差异均未达显著水平;大蒜根系分泌物对受试作物叶绿素含量及根系活力有促进作用,与对照差异达显著水平,对萝卜的叶绿素含量促进作用最强,化感效应指数为+0.282,对黄瓜的根系活力促进作用最强,化感效应指数为+0.184;大蒜根系分泌物使受试作物对养分的吸收能力有所提高.     

环糊精对绿豆下胚轴不定根形成的影响

10-3-10-2mol／β-环糊精能明显促进绿豆插条不定根根原基形成,增加不定根数目和总根长．10-4-10-2mol／Lβ-环糊精能提高不定根的鲜重、干重和可溶性蛋白质含量,降低IAA氧化酶活性,减少不定根的平均根长,但对下胚轴的鲜重和干重影响不明显．10－3mol／Lβ-环糊精能提高插条的不定根活力．     

外源人参皂苷对人参种子萌发和幼根抗氧化酶活性的影响

研究不同浓度外源人参皂苷(人参总皂苷,人参二醇组皂苷,人参三醇组皂苷, Rb族,Rb3,Re共4种皂苷混合物和两种单体皂苷)对人参种子萌发,幼苗根长、鲜重,幼根中抗氧化酶活性和MDA含量的影响.结果表明:所测试人参皂苷对人参种子萌发、人参幼苗根长生长和幼根鲜重增加均具有抑制化感效应,且抑制程度均随处理浓度的升高而增强;对人参幼根中抗氧化酶活性方面,不同浓度人参总皂苷,人参二醇组皂苷,人参三醇组皂苷处理后,人参根系中SOD,POD和CAT活性均有明显提高,呈现出各酶活性随浓度升高而逐渐增强的效应;人参皂苷Rb族处理后,SOD活性在低中浓度处理时,与对照差别不大,中高浓度处理后低于对照,POD活性在中高浓度处理后显著提高,高浓度处理后活性降幅较大难以恢复到对照水平,CAT活性均低于对照;人参皂苷Rb3处理后,SOD活性均低于对照水平,POD活性在低浓度处理时与对照相当,中高浓度处理后显著低于对照水平,CAT活性逐渐降低,在低中浓度处理时略高于对照,高浓度处理后低于对照水平;人参皂苷Re处理后,SOD和POD活性均显著低于对照.人参幼根中MDA含量均随着处理浓度的增加而升高.     

人参根系发育形态学的研究

人参(Panax qinseng C. A. Meyer)属于直根系植物,有次生构造。一年生苗只具有主根和侧根。二年以上的人参常在根状茎上长出不定根,即人参根系包括主根和不定根及其各级分枝。主根初生木质部为三原型,侧根和不定根及其分枝多为二原型,偶见三原型。根系随参龄的增加而增大。每年末级分枝自基部于休眠前萎缩、脱落,并在萎缩部分的上一级支根内部产生越冬根原基,越冬根原基是翌年形成全部吸收根的基础。一年生人参由中柱鞘产生一圈初生树脂道,由形成层产生一圈(或二圈)次生树脂道,以后次生树脂道的圈数随参龄的增加而每年增加一圈,自第五年开始渐缓。根内淀粉粒含量随发育时期的变化而相应变化,其积累高峰出现在果后期。研究人参根系发育形态学不仅对全面正确认识人参根系具有理论意义,而且对改进人参栽培管理和评价人参质量具有指导意义。     

小蓬草精油的化感效应

小蓬草精油化感作用研究结果表明不同浓度小蓬草精油对青菜、白菜、小麦、稗草和鹅观草的种子最终发芽率、种子发芽指数、幼苗根长、幼苗根系活力、幼苗叶绿素含量、幼苗叶绿素a含量和幼苗叶绿素b含量的化感效应敏感指数均为负值,小蓬草精油对五种植物具有抑制作用,且精油浓度越高抑制作用越强.小蓬草精油主要通过抑制青菜、白菜、小麦、稗草和鹅观草的种子发芽速率、幼苗根系活力和叶绿素含量来抑制受体植物生长.不同浓度小蓬草精油对五种植物种子最终发芽率、种子发芽指数和幼苗根长的影响中,鹅观草对小蓬草精油最为敏感,小蓬草精油对鹅观草种子萌发的半抑制浓度(IC50)为0.42 g L-1.     

薄壳山核桃根系水浸提液对2种作物种子萌发及幼苗生长的影响

为探讨薄壳山核桃根系水浸提液对小麦、大豆的影响,采用蒸馏水浸提法收集薄壳山核桃根系化感物质,并运用室内生物测定法检测不同浓度(0.025、0.05和0.1 g·mL~(-1))根系水浸提液对小麦、大豆种子萌发和幼苗生长的影响。结果表明:各浓度处理的根系水浸提液对小麦、大豆萌发及幼苗生长的化感抑制作用较为显著,且具有显著的浓度效应(浓度低抑制作用弱,浓度高抑制作用强);薄壳山核桃根系水浸提液对小麦、大豆种子发芽率、发芽指数、发芽势和活力指数的抑制作用分别依次为:活力指数发芽势发芽指数发芽率和活力指数发芽势发芽率发芽指数;薄壳山核桃根系水浸提液各浓度处理对小麦、大豆幼苗根长、苗高、鲜质量和干质量的化感效应均为:根长苗高鲜质量干质量,其中薄壳山核桃根系水浸提液对2种受体植物幼苗根长均有显著的抑制作用,而对幼苗干、鲜质量的影响则因受体植物种类的不同而不同;薄壳山核桃根系水浸提液对2种受体植物的综合化感效应顺序为:小麦大豆;生长7 d的幼苗体内,SOD活性降低,MDA含量、POD活性和CAT活性与对照相比均随浓度的增加而增加。综合分析认为:小麦对薄壳山核桃根系水浸提液更为敏感。     

NaCl胁迫对黄瓜根系边缘细胞发生的影响

以黄瓜为试材,研究了NaCl处理对植株生物量、根长、根系活力、根边缘细胞的数目和活性及黏胶层厚度的影响。结果表明,NaCl处理降低了植株生物量与根系长度,增加了黄瓜幼苗的根系活力。黄瓜边缘细胞的出现几乎与根同时发生,当根长达到25mm时,边缘细胞的数目与活性均达到最大值。NaCl处理对边缘细胞的数目与活性表现出一定的抑制作用。离体根尖的边缘细胞活性也随NaCl处理浓度与处理时间的增加而逐渐减小,但根边缘细胞黏胶层厚度却随NaCl处理浓度的增加而增加。总之,NaCl对黄瓜幼苗造成一定伤害,但根系边缘细胞可通过降解死亡与增加黏胶的分泌量在一定程度上减轻这种伤害程度。     

豌豆根系中分泌物质的分离鉴定及其化感效应的研究

本文实验采用GC-MS分析法对豌豆组培苗、土培苗重茬两代的根系分泌物进行鉴定。实验结果表明,能被二氯甲烷提取的豌豆根系分泌物有醇类、脂类、醛类、苯类、烃类等。用不同浓度的豌豆化感物质2,4-二叔丁基苯酚(2,4-DB)和2,6-二叔丁基对甲酚(2,6-DM)处理豌豆、绿豆、小麦和玉米4种作物种子,进行萌发和幼苗生长的化感效应研究。结果表明,0~2 mmol·L~(-1) 2,4-DB和2,6-DM处理对豌豆和绿豆种子萌发呈促进作用,而3~5 mmol·L~(-1) 2,4-DB和2,6-DM处理则呈抑制的作用。随浓度的增大,2种化感物质对小麦和玉米种子萌发的抑制作用逐渐增强。对于豆科作物豌豆和绿豆,2,4-DB对绿豆萌发时根系的抑制作用较强;而对于禾本科作物玉米和小麦,则2,4-DB对小麦萌发时根系的抑制作用最强。     

香附浸提液对小麦种子的萌发及幼苗生长的影响

为了了解香附有效成分对小麦种子萌发和幼苗生长的影响,采用室内培养皿培养法,分析不同浓度的香附浸提液浸种后对小麦种子发芽率、发芽指数、活力指数及幼苗高度、根长、根数、整株鲜重及干重等指标的影响。结果表明,香附浸提液对小麦种子的萌发及幼苗的生长有明显抑制作用,抑制作用随着香附浸提液浓度的增加,抑制效果增强,与浸泡蒸馏水的对照相比,香附浸提液浸种处理显著降低了小麦的种子发芽率、发芽指数、种子活力、苗高、根长、植株鲜重和干重。     

滇重楼种子水浸液对三种植物种子萌发和幼苗生长的影响

利用滇重楼(Paris polyphylla Smith var.yunnanensis(Franch.)Hand.-Mazz.)种子外种皮和胚乳的水浸液对白菜(Brassica pekinensis(Lour.)Rupr.)、绿豆(Vigna radiata(Linn.)Wilczak)、小麦(Triticum aestivum L.)种子进行处理,研究滇重楼种子水浸液对3种植物种子萌发、幼苗生长和保护酶活性的影响,并利用GC-MS方法对滇重楼种子内源抑制物的成分进行分析。结果显示,不同浓度滇重楼外种皮、胚乳水浸液对上述3种受体植物的发芽率、苗高、根长及鲜重均产生影响,其作用强度和水浸液的浓度有关,总体上表现出低促高抑的双重浓度效应。滇重楼种子水浸液对白菜的影响作用最强,对绿豆的影响作用最弱,且胚乳水浸液的影响较外种皮强。不同浓度滇重楼种子外种皮和胚乳水浸液均能影响3种植物幼苗体内保护酶的活性,随着水浸液浓度的升高,叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)活性总体增加,与对照相比差异显著。白菜、小麦过氧化氢酶(CAT)活性减少,与对照相比差异显著;绿豆过氧化氢酶(CAT)活性增加,但与对照相比无显著差异。利用GC-MS方法从胚乳和外种皮水浸液中分别检出8种和2种物质。研究结果表明滇重楼种子中存在内源抑制物质,可能是导致种子休眠的原因;种子水浸液可能通过影响植物幼苗保护酶的活性进而影响其正常生长;有机酸类物质可能是滇重楼种子内源抑制物之一。     

Chilli rhizosphere fungus Aspergillus spp. PPA1 promotes vegetative growth of cucumber (Cucumis sativus) plants upon root colonisation

A rhizosphere fungus was isolated from roots of chilli plants and identified as Aspergillus spp. PPA1. The fungus was tested for its ability to promote the growth of cucumber plants in a pot experiment. Cucumber seeds were sown in sterilised field soil amended with wheat grain inoculum (WGI) of PPA 1 at the rate of 0.5, 1 and 1.5% w/w, and plants were grown for 21 days in a net house. The treatment with PPA1 significantly increased shoot length, shoot fresh weight, shoot dry weight, root length, root fresh weight, root dry weight, plant length, leaf area and leaf chlorophyll content of cucumber plants compared to non-treated control. The growth promotion rate increased with the increasing concentration of inoculum of PPA1 applied to the soil. The fungus was re-isolated from the roots of cucumber plants at higher frequencies. These results suggest that Aspergillus spp. PPA1 is a root colonising plant-growth promoting fungus for cucumber.     

铁核桃根与叶水浸提液对果园间作绿肥植物的化感作用及其生理机制

以西南地区具有代表性的16种绿肥植物为受体材料,采用培养皿药膜法研究了铁核桃(Juglans sigillata)根水浸提液对受体种子发芽率及幼苗鲜重、干重的化感效应;并进一步研究了铁核桃根、叶水浸提液和胡桃醌对化感效应存在明显差异的4种绿肥植物(绿豆、红三叶、白三叶、花生)种子萌发与幼苗生长以及抗氧化酶特性的影响,以筛选适宜中国西南地区核桃园种植的绿肥植物,探讨核桃根和凋落物对绿肥作物的化感作用机制。结果表明:(1)铁核桃根水浸提液对绿豆的发芽率没有影响,但对绿豆幼苗鲜重和干重有显著抑制作用,而对其他15种绿肥的发芽率和鲜重、干重均有抑制作用。(2)胡桃醌显著抑制绿豆种子萌发,而铁核桃根或叶水浸提液对绿豆种子萌发没有影响。(3)铁核桃根或叶水浸提液以及胡桃醌对绿肥植物幼苗生长的化感效应趋势一致,但核桃根或叶水浸提液的化感效应强于胡桃醌。(4)绿豆幼苗在铁核桃根或叶水浸提液以及胡桃醌处理下,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)的活性均高于其他3种(红三叶、白三叶、花生)受体幼苗,表明绿豆清除活性氧能力高,细胞受损害程度较低,受化感作用影响最弱。研究认为,绿豆为适宜中国西南地区幼龄核桃园种植的间作绿肥植物。     

甘蔗废糖蜜对绿豆插条下胚轴生根的影响

本文研究甘蔗废糖蜜对绿豆插条下胚轴生根的影响,结果表明,1000~7000mg/L浓度范围内的甘蔗废糖蜜能明显增加绿豆插条下胚轴不定根的数目、根长、根干重及生根范围,并促进不定根内可溶性糖含量和不定根系活力提高。     

Ferulic acid impairs rhizogenesis and root growth,and alters associated biochemical changes in mung bean (Vigna radiata) hypocotyls

The present study investigated the effect of ferulic acid (FA; 0–1000 µM) on early growth, and rhizogenesis in mung bean (Vigna radiata) hypocotyls and associated biochemical changes. FA severely affected the radicle elongation and number of secondary roots after 72 h. The root and shoot length, number and length of secondary roots, and seedling dry weight of one-week-old seedlings of mung bean were decreased by 64%. The rooting potential (percent rooting, number and length of adventitious roots) of mung bean hypocotyls under in vitro conditions was significantly inhibited in response to 1–100 µM FA. At 1000 µM there was complete cessation of rooting. FA caused a reduction in the contents of water-soluble proteins and endogenous total phenolics, whereas the activities of proteases, peroxidases, and polyphenol peroxidases increased. The study concludes that FA inhibits root growth and development, and in vitro rooting process in mung bean by interfering with biochemical processes that are crucial for root formation.     

Caffeic acid affects early growth, and morphogenetic response of hypocotyl cuttings of mung bean (Phaseolus aureus)

Caffeic acid (CA) is one of the most common cinnamic acids ubiquitously present in plants and implicated in a variety of interactions including allelopathy among plants and microbes. This study investigated the possible interference of CA with root growth and the process of rhizogenesis in hypocotyl cuttings of mung bean (Phaseolus aureus=Vigna radiata). Results indicated that CA (0-1000 microM) significantly suppressed root growth of mung bean, and impaired adventitious root formation and root length in the mung bean hypocotyl cuttings. Further investigations into the role of CA in hampering root formation indicated its interference with the biochemical processes involved in rooting process at the three stages - root initiation (third day; RI), root expression (fifth day; RE), and post-expression (seventh day; PE) - of rhizogenesis. CA caused significant changes in the activities of proteases, peroxidases (PODs), and polyphenol oxidases (PPOs) during root development and decreased the content of total endogenous phenolics (TP) in the hypocotyl cuttings. The enhanced activity of PODs and PPOs, though, relates to lignification and/or phenolic metabolism during rhizogenesis; yet their protective role to CA-induced stress, especially during the PE phase, is not ruled out. At 1000 microM CA, where rooting was significantly affected, TP content was very high during the RI phase, thus indicating its non-utilization. The study concludes that CA interferes with the rooting potential of mung bean hypocotyl cuttings by altering the activities of PODs and PPOs and the endogenous TP content that play a key role in rhizogenesis.     

The changes in the growth pattern of organs ofChenopodium rubrum photoperiodically induced to flowering

The relationship between photoperiodically changed growth of leaves, cotyledons, hypocotyl, roots and flowering has been investigated inChenopodium rubrum. It was found that all the growth characteristics recorded in leaves and cotyledons,i.e. length, area, dry weight and chlorophyll content, were inhibited during three inductive photoperiods (16 h darkness, 8 h light-SD) as compared with control plants grown under continuous illumination. Similarly, the cessation of root elongation and a decrease in root dry weight were observed. On the contrary, the elongation and dry weight of hypocotyl are stimulated by SD. The degree of the effect exerted by SD on the growth of different organs depends both on actual growth stage and the number of SD photoperiods. Increased relative rate of growth of roots and cotyledons was recorded in plants transferred after SD treatment to continuous illumination. However, this rise possesses only transitional character and the relative growth rate of treated plants equals that of control ones afterwards. The above growth changes are discussed as a possible modifying factor of floral differentiation.     

Growth promotion effect of Fusarium spp. PPF1 from bermudagrass (Cynodon dactylon) rhizosphere on Indian spinach (Basella alba) seedlings are linked to root colonisation

A rhizosphere fungus was isolated from roots of bermudagrass (Cynodon dactylon) and identified as Fusarium spp. PPF1. A pot experiment was conducted to test its ability to promote the vegetative growth of Indian spinach seedlings (Basella alba). Indian spinach seeds were sown in sterilised field soil amended with wheat grain inoculum of PPF1 at the rate of 0.5 and 1.0% w/w, and plants were grown for 21?days in a net house. Significantly, higher germination percentage and vigour index were observed due to application of PPF1 in the potting soil. Treatment with PPF1 also significantly increased shoot length, shoot fresh weight, shoot dry weight, root length, root fresh weight, root dry weight, leaf area and leaf chlorophyll content of cucumber plants compared to non-treated control. The growth promotion rate increased with the increasing concentration of inoculum of PPF1 applied to the soil. The fungus was re-isolated from the roots of cucumber plants at higher frequencies, while a positive co-relation was found between the root colonisation ability and the plant growth enhancement by the isolate. These results suggest that growth promotion effect of Fusarium spp. PPF1 on Indian spinach (B. alba) are linked to root colonisation ability of the fungus.     

The Effect of the Ethylene Action Inhibitor 1-Cyclopropenylmethyl Butyl Ether on Early Plant Growth

Increased levels of ethylene in plants are responsible for many deleterious effects such as early senescence, fruit deterioration and inhibition of root elongation. Several cyclopropene derivatives have previously been studied as inhibitors of ethylene action in plants. This study focuses on one such compound, 1-cyclopropenylmethyl butyl ether and its effect on the growth of roots and shoots of canola plants as well as rooting of mung bean seedlings 1-cyclopropenylmethyl butyl ether increased root length in canola plants, but had no significant effect on shoot length. In rooting studies, mung bean seedlings treated with 1-cyclopropenylmethyl butyl ether prior to root excision had fewer numbers of roots than control plants that were not treated with the ethylene action inhibitor. The same rooting study, when repeated in the presence of 1-aminocyclopropane-1-carboxylic acid (ACC), demonstrated an overall increase in the number of roots of inibitor-treated and non-treated plants, however, the inhibitor was still effective in decreasing the number of roots, compared to its non-treated conterpart. Online publication: 7 April 2005