马铃薯对瓜列当种子萌发的化感作用研究

瓜列当给瓜类等经济作物造成较大危害。本研究采用盆栽4个推广马铃薯品种"夏波蒂"、"青薯168"、"冀张薯5号"和"克新1号",以不同生长时期(幼苗期、开花期和结薯期)马铃薯根际土、根系和地上部的浸提液(甲醇和水)刺激瓜列当种子萌发,根据发芽率来判定其对瓜列当化感作用的强弱,同时筛选刺激瓜列当发芽率高的品种用于列当杂草的防除。结果表明,马铃薯能刺激瓜列当种子萌发;不同马铃薯品种对瓜列当的化感作用各有差异,随着马铃薯的生长,根际土中化感物质积累不断升高,根系化感作用逐渐减弱,而地上部化感作用逐渐增强。甲醇浸提液刺激瓜列当种子发芽率高于水浸提液,即甲醇浸提化感作用效果较好。"夏波蒂"根系甲醇浸提液刺激瓜列当种子的发芽率在幼苗期最高,为48.5%;而地上部甲醇浸提液处理的发芽率在结薯期最高,为51.2%。可以在瓜列当危害的农田轮作"夏波蒂"5~8年,同时采用马铃薯秸秆还田来减少土壤中瓜列当种子库,达到防除瓜列当危害的目的。     

Isolation and Identification of Potent Allelopathic Substances in a Traditional Bangladeshi Rice Cultivar Kartikshail

Abstract

Aqueous methanol extracts of a traditional Bangladeshi rice cultivar (Oryza sativa L. cv. Kartikshail) inhibited root and shoot growth of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), timothy (Phleum pratense), crabgrass (Digitaria sanguinalis), Italian ryegrass (Lolium multiflorum), barnyardgrass (Echinochloa crus-galli) and jungle rice (Echinochloa colonum). The inhibition was increased with increasing the extract concentration, which suggests that cv. Kartikshail may have growth inhibitory substances and allelopathic potential. The aqueous methanol extract of cv. Kartikshail was purified and two main inhibitory substances were isolated and identified by spectral data as 3-hydroxy-β-ionone and 9-hydroxy-4-megastigmen-3-one. The concentrations required for 50% growth inhibition on cress roots and shoots, respectively, were 4.9 and 9.5 μM for 3-hydroxy-β-ionone, and 0.54 and 0.72 μM for 9-hydroxy-4-megastigmen-3-one. The concentrations required for 50% growth inhibition on barnyardgrass roots and shoots, respectively, were 160 and 310 μM for 3-hydroxy-β-ionone, and 53 and 140 μM for 9-hydroxy-4-megastigmen-3-one. The inhibitory activity of a mixture of the two compounds was much higher than that of the sum of the two compounds, suggesting that the two compounds may act synergistically to inhibit the growth of cress and barnyardgrass. The present research suggests that 3-hydroxy- β-ionone and 9-hydroxy-4-megastigmen-3-one may be responsible for the growth inhibitory effect of cv. Kartikshail and may play important roles in the allelopathy of cv. Kartikshail. The traditional Bangladeshi rice cultivar Kartikshail may be potentially useful for weed management as a weed suppressing agent when this rice cultivar is incorporated into the soil or included in rice-based cropping systems.     

Does Allelopathy Play a Role in Suppression of Mugwort (Artemisia vulgaris) by Alfalfa?

Abstract

Alfalfa suppresses mugwort growth in the field. In the present study, the allelopathic effect of alfalfa on mugwort was examined using the above-ground (AGAB) and under-ground alfalfa biomasses (UGAB), and their water extracts. The sprouting of mugwort rhizomes or seed germination, growth of seedlings and leaf color changes in mugwort seedlings were evaluated in pot experiments. AGAB mixed into soil highly inhibited sprouting of mugwort rhizome fragments and growth of seedlings. The inhibitory effect was increased, and gradual leaf discoloration (yellowing) was observed in response to a higher dose of AGAB. However, UGAB affected neither sprouting of mugwort rhizome fragments nor growth of seedlings. The growth of mugwort seedlings was not significantly affected by water extracts of either AGAB or UGAB applied after emergence. The seed germination and seedling growth were significantly reduced by water extracts of AGAB and UGAB in the petri dishes experiments. These results indicated that the allelopathic effect of alfalfa along with the competitive ability and harvesting regime may play an important role in suppressing mugwort growth.     

Growth Stage of Cyperus esculentus Influences Its Allelopathic Effect on Ectomycorrhizal and Higher Plant Species

Summary

Live plants and plant material in various forms have important roles in ecological processes. Weeds may be involved in interactions with desirable species at different trophic levels through the production and release of allelochemicals. The allelopathic potential of the weed Cyperus esculentus (yellow nutsedge) was assessed by preparing aqueous extracts from tubers and foliage from immature or mature plants, and testing their effects on an ectomycorrhiza and two higher plant species. The extracts from tubers and both foliage types significantly reduced the colony diameter of the ectomycorrhiza Boletus maxaria, which was isolated from roots of the forestry species Pinus patula, on agar medium. Extracts (2% m/v) from C. esculentus tubers and the foliage of immature plants inhibited the germination of lettuce (Lactuca sativa) seeds significantly. At 5% concentration, the extracts from foliage of immature weed plants completely inhibited the germination of lettuce seeds at the end of the 7-day trial period. The emergence of corn (Zea mays) was retarded in soil where C. esculentus tubers were planted 28 days before planting the crop, irrespective of whether the weeds continued to grow or were physically removed at the time the corn was sown. In contrast, where weed tubers and corn seeds were planted at the same time, emergence of corn was not affected. It is suggested that the growth stage of weeds be considered in the assessment of their direct and indirect allelopathic effects, and in predictions for their impacts on crop development and yield.     

Allelopathy in Agroecosystems in Spain

Summary

This paper reviews the effects of allelopathic interactions in agroecosystems in Spain on plant physiological activity and their ecological advantages. The phenological stage of growth of donor plants and the effective allelochemicals in the soil solution while studying the role of phenolic compounds were highlighting. Finally possible future prospects and conclusions regarding weed control by allelochemi-cals under integrated crop management strategies are discussed.     

Allelopathic Influence of Decomposing Wheat Residues in Agroecosystems

Summary

The concept that some crop plants have allelopathic effects is receiving greater attention as a potential mean that can be exploited in various ways for controlling agricultural pests. Wheat residues have been reported to inhibit growth of certain weeds, crops that follow wheat crop in crop rotation, soil nitrification and biological nitrogen fixation. Thus, crop production can be enhanced by avoiding the inhibitory effects or by exploiting favorable interactions. The present article presents an overview of research on the allelopathic influence of wheat residues in agroecosystems.     

不同秸秆及绿肥浸提液对玉米化感作用的研究

采用室内培养试验,通过测定油菜秸秆、小麦秸秆、紫云英及紫云英+油菜秸秆4种浸提液对玉米发芽、幼苗生长及干重的影响,研究不同秸秆及绿肥对玉米的化感作用。结果表明,当浸提液浓度≥10 g/L时显著降低玉米发芽率。除紫云英+油菜秸秆浸提液对幼苗生长及干重表现为较强抑制作用外,其他浸提液均表现为显著促进作用或微弱抑制作用,紫云英浸提液促进作用最强,其中,油菜秸秆、小麦秸秆、紫云英浸提液均在5 g/L时对幼苗总干重的促进作用最大,分别较对照提高10.85%、11.51%、16.71%。除紫云英+油菜秸秆外,其他秸秆及绿肥对玉米的化感作用整体上均表现为促进作用,油菜秸秆、小麦秸秆、紫云英及油菜+紫云英浸提液的综合敏感指数分别为2.64%、3.59%、10.32%、-7.33%。     

银杏凋落叶对生菜生长及生理特性的影响

采用盆栽试验,通过向土壤中施加不同量(0、2.5、5.0、7.5、10.0 g/kg)的银杏凋落叶,研究银杏凋落叶对生菜生长及生理特性的影响。结果表明:在土壤中施用银杏凋落叶后显著抑制了生菜的生长,其根长、茎粗和株高均显著下降,地上部鲜物质量较对照分别减少了11.38%、22.54%、32.37%、34.82%;各处理生菜叶片中叶绿素含量较对照均显著减少,且随凋落叶施用量的增多呈现降低趋势,10.0g/kg银杏凋落叶处理下的叶绿素a、叶绿素b、总叶绿素以及类胡萝卜素含量分别比对照减少45.24%、56.25%、47.72%以及38.08%;生菜叶片中超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性较对照均有所增强,且各处理中后两者酶活性均显著高于对照;各处理生菜叶片丙二醛(MDA)含量均小于对照,且随凋落叶施用量增多呈增加趋势。研究认为,银杏凋落叶对生菜生长及抗性生理产生化感作用,综合表现为抑制作用。     

Isolation and characterization of a germination inhibitor from leaves of Empetrum hermaphroditum hagerup

An extract of Empetrum hermaphroditum Hagerup leaves was examined for germination inhibitors using an assay based on germination of Populus tremula L. seeds. The substances were extracted in water and purified by solvent partitioning. The acidic ethyl acetate fraction, containing the major part of the inhibitory activity was purified by reversed‐phase high‐performance liquid chromatography. Two zones of inhibitory activity were detected, combined and further purified by normal‐phase HPLC. One major zone of inhibitory activity was thereafter detected and the substance in this fraction was crystallized and identified by nuclear magnetic resonance and gas chromatography‐mass spectrometry as 5‐methoxy‐3,3´‐dihydroxy‐dihydrostilbene or batatasin III. Ca. 100 mg of the substance was then, by sequential HPLC, isolated in crystalline form from E. hermaphroditum leaves. The inhibitory activity of the pure substance was compared with a crude water extract of E. hermaphroditum leaves. It was concluded that the pure substance exhibited ca. 28 % of the inhibitory activity of the crude extract. The difference in inhibitory activity might be explained by the presence of a glucosidic conjugate of 5‐methoxy‐3,3´‐dihydroxy‐dihydrostilbene in the crude extract.     

板栗苞壳水浸液对5种作物种子萌发的化感效应

通过测定板栗苞壳水浸液对5种作物种子发芽和幼苗生长的影响,初步研究板栗苞壳的化感效应。结果表明,板栗苞壳水浸液对5种受体作物种子的萌发、幼苗生长均有不同程度的抑制作用,随水浸液质量浓度的增加,对受体作物种子的萌发、幼苗生长的抑制效应增加;随水浸液质量浓度的降低,抑制作用逐渐减弱、消失,甚至转变为促进作用。板栗苞壳水浸液对同一受体作物的不同部位(芽和根)也有不同的化感效应,高质量浓度水浸液对幼苗的抑制作用表现为幼根比幼芽更敏感,低质量浓度水浸液对白菜和绿豆幼苗的促进作用表现幼芽比幼根更敏感,小米和高粱幼苗的促进作用表现幼根比幼芽更敏感。相同质量浓度水浸液对不同作物种子的化感效应不同,高质量浓度水浸液对白菜种子的抑制作用最强,对小米种子的抑制作用最弱;低质量浓度水浸液对小米种子的促进作用最强,对小麦种子的促进作用最弱或无促进作用。