Screening of 170 Peruvian plant species for allelopathic activity by using the Sandwich Method

Peru is one of the 20 botanically extremely diverse countries in the world, with >17 000 flowering plants, of which 30% are endemic. So far, no systematic research has been conducted on the screening of the allelopathic plants. In this study, the allelopathic activity of 170 species from 61 families of Peruvian plants that were collected from the three main regions of Peru – the Costa (Pacific coastline), the Sierra (Andean mountains), and the Selva (Amazonian rainforest) – was evaluated. The allelopathic activity was determined by the Sandwich Method, which can evaluate the activity of leaf leachates. The species that were found to be highly inhibitory in this screening, under the criterion of >90% inhibition of the radicle of lettuce (Lactuca sativa) seedlings, were Aristeguietia ballii and Diplostephium foliosissimum (Asteraceae) and Spondias mombin (Anacardiaceae). All of these species are native plants from Peru. This study gives a strong clue regarding the potential of isolating potent allelochemicals from these plants in the future.     

A perspective on the role of quantitative structure-activity and structure-property relationships in herbicide discovery

BACKGROUND: For the last 15 years the agrochemical industry has focused on using genetic modification to put genes that confer resistance to existing commercial herbicides into crop plants rather than on discovering new herbicides with novel modes of action. The widespread appearance of weeds resistant to those herbicides is now causing the industry to revive their herbicide discovery programs. RESULTS: Elucidation of quantitative structure–activity relationships (QSARs) played a major role in the discovery and development of existing commercial herbicides, but the advent of genetically modified crops has caused published work (at least) in the area to drift from the industrial arena into academic studies. The focus has also turned inward, to refining models for established herbicide targets instead of elucidating new ones. CONCLUSION: This perspective highlights the importance of QSARs and quantitative structure–property relationships (QSPRs) to herbicide discovery in an historical context and provides some guidance as to how they might profitably be applied going forward. Copyright © 2011 Society of Chemical Industry     

控释尿素对玉米产量、氮肥利用率及土壤氮素的影响

采用田间试验,研究了施用硅藻土为载体的控释尿素对玉米不同生育期地上部生物量、吸氮量以及土壤尿酶活性、硝态氮和铵态氮含量及产量和氮肥利用率的影响.结果表明:与普通尿素一次性施用相比,控释尿素能提高玉米生长后期地上部生物量和吸氟量,抑制脲酶活性,维持土壤氮素水平,提高玉米产量和氮肥利用率,其效果与普通尿素分次施用相当.尿素分次施用和控释尿素处理分别比尿素一次性施用处理产量增加23.48％和17.70％,氮肥利用效率提高17.33％和17.58％,这说明以硅藻土为载体的控释尿素替代普通尿素,一次性基施的施肥方式替代基肥加追肥是可行的,能达到省工、增效的目的.     

5种黔产药食两用植物的抗氧化活性

为寻找新的抗氧化物质及其进一步开发利用黔产植物提供理论依据,选取茯苓、玉竹、天麻、木瓜、百合5种黔产药食两用植物,测定其水提取液和乙醇提取液对自由基.OH、O-2·和DPPH·的清除能力,对其抗氧化能力进行评价。结果表明:5种药食两用植物对·OH、O-2·和DPPH·均具有一定抗氧化作用,其中木瓜对几种自由基的清除作用最强,具有作为天然抗氧化剂和功能性食品开发的潜力。     

南天竹提取液对植物病原菌的抑菌活性

为了探明提取南天竹的最佳溶剂和其提取液的抑菌活性,采用生长速率法测定了南天竹4种不同溶剂提取液对水稻纹枯病菌(Rhizoctonia solani)、番茄早疫病菌(Alternaria solani)、大葱紫斑病菌(Alternaria porri)和棉花枯萎病菌(Fusarium oxysporum f.sp.vasinfectum)的抑制作用。结果表明:南天竹4种不同溶剂提取液对4种植物病原菌菌丝生长速率都有一定的抑制作用。其中,南天竹乙酸乙酯提取液的抑菌活性能力最强,对水稻纹枯病菌、大葱紫斑病菌、番茄早疫病菌和棉花枯萎病菌的抑菌率分别为81.54%、73.71%、83.12%和82.81%,甲醇和乙醇提取液的抑菌活性能力次之,丙酮提取液的抑菌活性能力最弱。     

干旱胁迫对甘蔗近缘材料抗氧化系统酶活性的影响

本文报道了在干旱胁迫条件下甘蔗栽培种ROC22和ROC16与近缘种果蔗、大茎野生种、斑茅、割手密抗氧化系统相关酶活性的变化情况。结果表明:斑茅的POD、CAT活性和可溶性蛋白含量均最高,推测其是抗旱性强的材料。另外,甘蔗野生的近缘种斑茅、割手密、果蔗、大野的SOD、POD、CAT酶活性和可溶性蛋白含量均明显高于栽培种ROC22和ROC16,可以认为野生的甘蔗近缘种材料抗旱性高于栽培种。不同胁迫时间与SOD、POD、CAT酶活性存在一定的相关性,与可溶性蛋白含量存在负相关性。     

高产小麦品种济麦22旗叶叶绿素和活性氧清除系统酶活性的变化

为明确济麦22高产的生理基础,对其旗叶自然衰老过程中叶绿素含量和活性氧清除系统SOD、POD活性和MDA含量的变化进行了研究。结果表明,在自然衰老过程中,济麦22旗叶始终保持较高的叶绿素含量,其缓降期较长,使旗叶功能期延长,延缓了植株衰老,有效地提高粒重;旗叶细胞内SOD和POD保持较高的活性,且在花后24天后(蜡熟期)仍维持较高活性水平,可有效地清除活性氧自由基,防御其对叶片的伤害;MDA含量相对较低且上升幅度很小,叶片细胞的膜脂过氧化作用较弱。这些说明济麦22旗叶细胞酶促防御系统具有很强的活性氧清除能力,有效地抑制膜脂过氧化作用,从而延长旗叶的功能期,延缓植株衰老。小麦育种实践中选择持绿型品种是实现品种产量突破的重要措施。     

红景天多酚的提取及抗氧化活性研究

研究了不同萃取溶剂对红景天多酚萃取率的影响,并用DPPH(1,1-二苯基-2-三硝基苯肼)和O2.-(超氧阴离子)法研究了多酚的抗氧化活性。结果表明:水溶液中加入一定比例的甲醇、乙醇等有机溶剂可明显提高红景天多酚的萃取率,其中以50%乙醇的萃取率最高。红景天多酚对DPPH和O2.-的清除效果明显,最高可达90%。相关性分析表明,多酚的浓度与其抗氧化活性有一定的相关性。     

甜菜碱浸种对盐胁迫下棉花种子发芽及其幼苗生理活性的影响

以耐盐能力不同的中棉所12号和中棉所19号为材料,研究其在盐胁迫下甜菜碱浸种对棉花种子发芽及其幼苗防御性保护酶活性的影响。结果显示,盐胁迫抑制发芽和幼苗根系发育,但提高幼苗的SOD、POD和CAT活性;甜菜碱浸种,在一定浓度范围内可促进幼苗根系发育,提高其SOD、POD和CAT活性,增加脯氨酸含量,浓度600μg/ml时最高。两品种对盐胁迫及甜菜碱浸种后的反应一致。     

29种中草药提取物对嗜水气单胞菌的抑菌活性研究

[目的]筛选对嗜水气单胞菌具有较强抑制作用的中草药,为该菌引起的爆发性鱼病防治提供用药依据。[方法]采用水提法和醇提法分别提取29种中草药的有效成分,并研究了29种中草药对嗜水气单胞菌的体外抑菌作用。[结果]12种中草药提取物对嗜水气单胞菌有不同程度的抑制作用,其中诃子的水提物和醇提物的抑菌效果较好,其醇提物的最小抑菌浓度(MIC)为1.2 g/L。博落回、白屈菜、五倍子对嗜水气单胞菌也有较强的抑制作用,当其浓度为10.0 g/L时,抑菌圈直径均大于10 mm,其醇提物的最小抑菌浓度分别为2.4、4.8和4.8 g/L。[结论]博落回、白屈菜、五倍子可作为抗嗜水气单胞菌的筛选药物。