Allelopathy of buckwheat: Assessment of allelopathic potential of extract of aerial parts of buckwheat and identification of fagomine and other related alkaloids as allelochemicals

The allelopathic potential of buckwheat ( Fagopyrum esculentum ) was investigated. Field study showed that living buckwheat reduced weed biomass compared with plots without buckwheat. Laboratory study revealed that root exudates suppressed root and shoot growth of weeds and reduced weed dry weight. Sequential partitioning of the aqueous ethanolic extract of the aerial parts of buckwheat showed that the chloroform extract caused an 80% reduction in radicle elongation of lettuce seedlings at a concentration of less than 100 p.p.m. Fagomine, 4-piperidone and 2-piperidinemethanol were isolated and identified by ¹H and ¹³C nuclear magnetic resonance from the chloroform extract. These compounds caused a 50% inhibition of radicle elongation in lettuce seedlings at concentrations of less than 100 p.p.m. These results suggest that compounds 1, 2, and 3 might act as allelochemicals and affect the growth or germination of different plant species.     

13种木本植物不同器官和浒苔对生菜幼苗生长的影响

为了明确13种常见的木本植物不同器官及浒苔的化感活性,为其有效利用提供依据,以生菜为受体,采用琼脂混粉法测定了它们在0.005～0.5 g/L供试浓度下对生菜幼苗生长的影响.结果表明,在上述供试浓度下,13种木本植物不同器官及海洋藻类浒苔对生菜幼苗的生长均具有不同程度的影响,其中,在0.005 ～0.1 g/L的供试浓度下,金叶千头柏与碧桃的枝、紫丁香与紫荆的叶等器官均表现出了相对较高的刺激根系生长活性.其他植物器官刺激生长的活性相对较低,或表现为抑制活性.     

Testing the role of allelochemicals in different wheat cultivars to sustainably manage weeds

Background

Selecting wheat varieties with allelopathic potential or high competitiveness against weeds is a sustainable solution for organic farming to eliminate the use of synthetic herbicides. Wheat is one of the most economically important crops. This study focuses on screening the allelopathic or competitive potential of four wheat cultivars, Maurizio, NS 40S, Adesso and Element, on two weeds of interest due to acquired herbicide resistance, Portulaca oleracea and Lolium rigidum, through germination and growth bioassays and the identification and quantification of benzoxazinoids (BXZs) and polyphenols (phenolic acids and flavonoids).

Results

The different cultivars showed different abilities to manage surrounding weeds and different capacity to exude or accumulate specialized metabolites in the presence of those weeds. Furthermore, each cultivar behaved differently depending on the weed present in the medium. The most efficient cultivar to control the tested monocot and dicot weeds was Maurizio, as it effectively controlled germination and growth of L. rigidum and P. oleracea while exuding large amounts of benzoxazinones through the roots, especially the hydroxamic acids 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one and dihydroxy-2H-1,4-benzoxaxin-3(4H)-one. By contrast, NS 40S, Adesso and Element showed the potential to control the growth of just one of the two weeds through allelopathy or competition.

Conclusion

This study reveals that Maurizio is the most promising wheat cultivar for sustainable weed control, and that the screening of crop varieties with allelopathic potential, which results in the displacement of synthetic herbicides, is an immediate solution in ecological and sustainable agriculture. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

绿肥和施氮对旱作冬小麦农田土壤酶活性的影响

基于田间定位试验研究了种植绿肥和施氮对旱作冬小麦农田土壤酶活性的影响。试验采用绿肥和氮肥双因素完全设计方案,其中绿肥作物在夏季休闲期种植,包括长武怀豆、苏丹草、怀豆+苏丹草混播和裸地休闲（对照）4种处理;氮肥于冬小麦播前施入,包括0、60、120 kg·hm^-2共3个水平;观测指标包括土壤β-葡萄糖苷酶、纤维二糖水解酶、乙酰氨基葡萄糖苷酶、亮氨酸氨基肽酶活性。结果表明,与对照相比,休闲期种植怀豆、苏丹草、怀豆+苏丹草混播均显著提高了以上4种土壤总体酶活性,0～10 cm和10～20 cm土层增幅分别达12.9%～59.3%和6.19%～48.8%。土壤β-葡萄糖苷酶和纤维二糖水解酶活性在不同绿肥处理间无显著差异,而种植怀豆较种植苏丹草和混播显著提高了乙酰氨基葡萄糖苷酶和亮氨酸氨基肽酶活性。施氮肥对土壤酶活性具有显著促进作用,且4种土壤酶活性均随着施氮水平提高而增加。氮肥与绿肥对纤维素二糖水解酶活性具有交互影响。黄土高原旱作种植系统休闲期间可以考虑通过种植绿肥作物尤其是豆科绿肥来提高肥力。     

金荞麦的潜在分布区及生态特征

为了解我国金荞麦Fagopyrum dibtrys(D.Don)Hara的潜在分布区及生态特征,基于38个环境因子以及金荞麦在我国的153个地理分布记录,应用最大熵模型(MaxEnt)与地理信息系统(GIS)对金荞麦进行生态适宜性区划,并采用自然间断法对金荞麦的潜在区域进行划分。结果显示,金荞麦的潜在分布区主要位于我国西南地区东部、华中地区、华东地区和华南地区(22 N°~35N°),总面积约为250.99×10~4km~2;将金荞麦的潜在分布区划分为适生区、低适生区与边缘适生区,其中适生区主要集中在长江流域,总面积为88.00×10~4km~2。影响金荞麦地理分布的主要生态因子有最冷月最低温、最暖季降水量、高程、最干季降水量等9个因子,其中气候因子对金荞麦的地理分布影响最大。表明金荞麦应在云南、贵州、四川等省扩大种植面积,陕西、山西等省可考虑引种。     

雷公藤总生物碱对几种昆虫的生物活性

为进一步确定雷公藤总生物碱的杀虫作用谱和作用方式,评价其应用前景,采用室内生测法研究了对小菜蛾、菜青虫、棉铃虫、黏虫、玉米象、桃蚜、山楂叶螨、家蝇的生物活性。结果表明,雷公藤总生物碱对小菜蛾3龄幼虫、黏虫3龄幼虫、菜青虫5龄幼虫、桃蚜无翅成蚜、山楂叶螨雌成螨和棉铃虫3龄幼虫48 h的毒杀活性LC50分别为228.28、306.39、307.61、0、435.90、622.17、653.00 mg/L,72 h后LC50分别为136.67、216.12、238.18、309.67、485.36、463.00 mg/L;对家蝇成虫也有较好的毒杀作用;对棉铃虫幼虫生长有明显抑制作用;对玉米象有较强的种群抑制作用。     

生物炭对土壤酶活性和糜子产量的影响

为探讨生物炭对土壤主要酶活性和糜子产量的影响,采用糜子盆栽种植方式,分别在砂土、壤土和盐土三种土壤上设置了生物炭施用量为B0(0 t·hm-2)、B15(15 t·hm-2)、B30(30 t·hm-2)、B45(45 t·hm-2)和B60(60 t·hm-2)五个水平。结果表明:砂土、壤土和盐土这三种土壤分别对应生物炭用量为45 t·hm-2、45 t·hm-2和30 t·hm-2时土壤总体酶活性(Et)达到最高,并且盐土、砂土和壤土的总体酶活性指标最大值分别比相应对照B0增加16.59%、7.29%、4.07%,说明生物炭对盐土酶活性的影响显著高于砂土,砂土高于壤土;在砂土中施用生物炭后,对糜子有明显的增产效果,而壤土和盐土上增产效果不显著;生物炭的施用还促进了砂土中糜子生物量的积累,并且在壤土上糜子的生物量的积累高于盐土和砂土。总之,在土壤中施用生物炭,不仅可以促进糜子增产,增加土壤总体酶活性,还可以改良土壤生物学特性。     

In vitro antimicrobial and in vivo antioomycete activities of the novel antibiotic thiobutacin

BACKGROUND: A number of synthetic fungicides are not effective when confronted by oomycete pathogens because many fungicide targets are absent from oomycetes. Moreover, resistance to fungicides has already arisen in oomycete species, and thus development of new, effective and safe compounds for use in oomycete disease control is necessary.RESULTS: Zoospore lysis began at 10 microg mL(-1) of thiobutacin, and most of the zoospores were collapsed at 50 microg mL(-1). Thiobutacin also revealed inhibitory activity against the cyst germination and hyphal growth of Phytophthora capsici at 50 microg mL(-1). Treatment with thiobutacin exhibited protective activity against development of Phytophthora disease on pepper plants.CONCLUSION: The authors verified in vitro antioomycete activity of thiobutacin against P. capsici and its control efficacy against Phytophthora blight in vivo. This is the first report to demonstrate in vivo antioomycete activity of the novel antibiotic thiobutacin against P. capsici infection.     

Structural effects of dinotefuran and analogues in insecticidal and neural activities

The insecticidal potencies of dinotefuran and analogues against the adult male American cockroach, Periplaneta americana (L) were measured by injection with or without metabolic inhibitors. The potency of dinotefuran was close to those of clothianidin and imidacloprid under the conditions used. The nerve-excitatory and nerve-blocking activities were measured with central nerve cords of P americana. The nerve-excitatory activity of dinotefuran was lower than that of imidacloprid, but was comparable with that of clothianidin. The nerve-blocking activity of dinotefuran was comparable with that of imidacloprid and slightly higher than that of clothianidin. Quantitative analyses showed that variations in the insecticidal activity were better correlated with variations in the nerve-blocking activity than with those in the nerve-excitatory activity when the contribution of the hydrophobic factor was allowed for.     

Preventive and post‐infection control of Botrytis cinerea in tomato plants by hexanoic acid

The antifungal activity of hexanoic acid on the phytopathogen Botrytis cinerea was studied. This chemical inhibited both spore germination and mycelial growth in vitro in a concentration‐ and pH‐dependent manner, and stopped spore germination at a very early stage, preventing germ‐tube development. The minimum fungicidal concentration (MFC) for in vitro spore germination was 16 mm . Hexanoic acid also inhibited in vitro mycelial growth of germinated spores at an MFC of 12 mm . Studies performed to characterize the mechanisms underlying the antimicrobial effect of hexanoic acid showed that it alters fungal membrane permeability. In addition, hexanoic acid treatment increased the levels of spermine, spermidine, putrescine and cadaverine in B. cinerea mycelia. Spray application of hexanoic acid at fungicidal concentrations on 4‐week‐old tomato plants prior to fungal inoculation reduced necrosis diameter by approximately 60%. Application of the same hexanoic acid concentrations on previously infected plants reduced further necrosis expansion by around 30%. The results suggest that this chemical acts as a preventive and curative fungicide. Interestingly, treatments with hexanoic acid at concentrations below the MFC in hydroponic solution prior to fungal inoculation significantly reduced necrosis area. These results suggest an inducer effect of plant responses for hexanoic acid treatments at these concentrations. Hexanoic acid is a good candidate for safe antifungal treatments for the control of B. cinerea, which is responsible for many economic losses on fruits, vegetables and flowers.     

来自大兴安岭凋落物的绿僵菌及其相近菌属真菌的生物活性

为研究绿僵菌Metarhizium及其相近菌属真菌的生物活性,采用形态学和分子生物学的方法对来自大兴安岭凋落物的肉色基思菌Keithomyces carneus（曾用名：肉色绿僵菌M.carneum）与马氏马昆德菌Marquandomyces marquandii（曾用名马昆德绿僵菌M. marquandii）以及金龟子绿僵菌Metarhizium anisopliae进行了鉴定,并分析了它们对3种害虫、4种植物病原菌的活性。杀虫活性测定表明,肉色基思菌与马氏马昆德菌对双斑萤叶甲Monolepta hieroglyphica、玉米蚜Rhopalosiphum maidis、绿豆象Callosobruchus chinensis具有侵染能力,为非寄主专化型真菌。抑菌活性测定表明,肉色基思菌对立枯丝核菌Rhizoctonia solani,水稻白叶枯病菌Xanthomonas oryzae pv. oryzae等病原菌具有抑菌活性。本研究揭示了3种供试真菌具有防治双斑萤叶甲的潜力,也发现了肉色基思菌与马氏马昆德菌的生防潜力,为它们进一步开发利用打下了基础。     

蝶蛹金小蜂寄生对菜粉蝶和玉带凤蝶蛹血细胞数量和组成的影响

以血球计数板较系统地考查了菜粉蝶和柑桔凤蝶雌雄蛹被蝶蛹金小蜂寄生后浆血细胞和颗粒血细胞数量的时间动态变化,以明确该蜂寄生对其寄主血细胞数量和组成的影响.结果表明,菜粉蝶蛹被寄生后,其血细胞总数除寄生后2天外均极显著高于同期未寄生蛹,最多的约高出20倍;除被寄生后0.5和5天的寄生蛹的血细胞组成与同期未寄生蛹无显著差异外,寄生后1～ 4 天雌雄寄生蛹的浆血细胞所占比例均显著低于同期未寄生蛹,而颗粒血细胞所占比例则反之.玉带凤蝶寄生蛹的血细胞总数在寄生后0.5 ～ 3天与同期未寄生蛹相比均无显著差异,但寄生后4 ～ 5天却显著升高,最多的约高出3倍;寄生后0.5 ～ 5天的寄生蛹浆血细胞所占比例均显著低于同期未寄生蛹,而颗粒血细胞所占比例恰反之.可见,该蜂寄生在一定时间内不仅能引起其两种寄主血细胞总数和颗粒血细胞所占比例明显增高,而且能导致浆血细胞所占比例明显下降.     

枸杞糖碱成分及其与土壤肥力间的关系研究

通过测定宁夏8个不同产区枸杞头茬果和盛果期果实中总糖、甜菜碱含量,研究枸杞中这两种成分的含量和比值变化以及它们与土壤肥力因子间的相互关系。结果表明:枸杞头茬果中总糖、甜菜碱含量均大于盛果期,而糖碱比在两茬间无显著性差异,但多数处于中糖中碱的优质枸杞范围内;土壤中的速效磷和速效钾是影响枸杞果实糖碱比的关键肥力因子。     

Enzyme-linked immunosorbent assay (ELISA) and dispersedye immuno assay (DIA): Comparison of simultaneous and separate incubation of sample and conjugate for the routine detection of lettuce mosaic virus and pea early-browning virus in seeds

Two modifications of ELISA and DIA were compared in relation to sensitivity of detection of two plant viruses and suitability for large-scale routine testing. DIA is a solid phase immuno assay like ELISA, in which the enzyme conjugate is replaced by a dye sol conjugate and substrate incubation is replaced by immediate dissolving of the dye molecules from the conjugate with an organic solvent. Sample and conjugate were incubated separately (ELISA 1, DIA 1) or simultaneously (ELISA 2, DIA 2). The seed-borne viruses viz. lettuce mosaic virus (LMV) and pea early-browning virus (PEBV) were subjected to the assays. DIA detected LMV in a purified extract ofNicotiana benthamiana. However, compounds present in crude virus-free and virus-containing plant extracts strongly interfered with DIA, necessitating adaptation of DIA to plant viruses in crude extracts.With the extracts of lettuce and pea seeds ELISA 2, in comparison with ELISA 1, resulted in equal (LMV) or slightly higher (PEBV) extinction values and in a higher ratio between extinction values of virus-containing and virus-free samples. The higher sensitivity of ELISA 2 in combination with its higher efficiency as a result of simultaneous sample and conjugate incubation, indicates the potential of this method for large-scale indexing.Samenvatting Twee modificaties van ELISA en DIA werden vergeleken met betrekking tot hun gevoeligheid voor het aantonen van twee plantevirussen en hun geschiktheid voor routinematige toepassing. DIA is een serologische toetsmethode die veel overeenkomst vertoont met ELISA, maar waarin het enzymconjugaat is vervangen door een conjugaat met gedispergeerde kleurstofdeeltjes en de incubatie met enzym-substraat door het direct oplossen van de kleurstofmoleculen van het conjugaat met een organisch oplosmiddel. Incubatie van monster en conjugaat vond zowel gescheiden (ELISA 1, DIA 1) als gelijktijdig (ELISA 2, DIA 2) plaats. Twee met zaad overgaande virussen, te weten slamozaïekvirus (LMV) en vroege-verbruiningsvirus van erwt (PEBV) werden bij het onderzoek betrokken. Met DIA kon LMV worden aangetoond in een gezuiverd extract vanNicotiana benthamiana. In ruwe planteëxtracten bleken echter stoffen voor te komen die in DIA sterke niet-specifieke reacties tot gevolg hadden. Verder onderzoek is dan ook noodzakelijk om DIA geschikt te maken voor het aantonen van plantevirussen in ruwe extracten van planten. Betere resultaten werden verkregen met de beide ELISA-modificaties. Met de extracten uit slazaad en erwtezaad gaf ELISA 2 vergelijkbare (LMV) of iets hogere (PEBV) extinctiewaarden dan ELISA 1. Bovendien was de verhouding tussen de extinctiewaarden van virusziek materiaal en die van virusvrij materiaal, bij ELISA 2 hoger dan bij ELISA 1. De grotere gevoeligheid van ELISA 2 en de grotere doelmatigheid ten gevolge van de gelijktijdige incubatie van monster en conjugaat duiden op de bijzondere geschiktheid van deze methode voor routinematige toepassing op grote schaal.     

Orobanche crenata resistance and avoidance in pea (Pisum spp.) operate at different developmental stages of the parasite

Orobanche crenata (broomrape) is an important constraint to pea (Pisum sativum) cultivation in the Mediterranean area, because little resistance is available in commercial crop varieties. Field experiments have demonstrated that some resistance is present in a number of P. sativum and P. fulvum accessions. The goal of this work was to characterize such resistance. The Pisum–O. crenata interaction and the resistance symptoms were studied under controlled conditions by using Petri dish and polyethylene bag assays. The content of phenolics and peroxidase activity in host tissue from infected and non-infected plants were also measured. Resistance and avoidance mechanisms, acting at different developmental stages of the parasite, have been identified, including low stimulation of O. crenata seed germination, unsuccessful penetration of host roots, delay in post-attachment tubercle development and necrosis of the attached tubercles. Infection caused an increase in the content of total soluble phenolics in some Pisum genotypes. Peroxidase activity was higher in resistant than in susceptible accessions. Results obtained with different Pisum genotypes showed that resistance is the result of several mechanisms acting at different stages of the infection process. Resistance is also related to increased levels of peroxidase activity in host roots.     

氟磺胺草醚对黑土微生物数量及酶活性的影响

为了探讨常用除草剂氟磺胺草醚的土壤环境效应,在东北黑土区豆-麦地进行大田试验,研究施用氟磺胺草醚后土壤速效磷(AP)、碱解氮(AN)和有机质(OM)3种养分含量、土壤微生物数量和土壤中酶活性的变化。氟磺胺草醚施用后土壤AP和AN含量没有显著变化,施用后30 d OM含量显著增加,其余天数均下降;施用后15 d细菌、真菌数量分别增加351.61%和220.00%,之后均呈下降趋势;氟磺胺草醚施用后放线菌数量降低,75 d后减少68.47%;施用氟磺胺草醚,土壤脲酶活性在1 d、蛋白酶和过氧化物酶活性在15 d和45 d、过氧化氢酶活性在1、15、75 d后都显著降低,而转化酶活性没有显著变化。研究表明,氟磺胺草醚的施用对土壤OM含量、微生物数量及脲酶、蛋白酶、过氧化物酶、过氧化氢酶活性均有一定的抑制作用,而对AP、AN含量和转化酶活性没有显著影响。     

Physiological Races and Vegetative Compatibility Groups of Fusarium oxysporum f. sp. lactucae Isolated from Crisphead Lettuce in Japan

One hundred and sixteen isolates of Fusarium oxysporum f. sp. lactucae obtained from 85 fields in three crisphead lettuce-producing areas in Nagano Prefecture, Japan were typed for races using differential cultivars Patriot, Banchu Red Fire and Costa Rica No. 4. They were also grouped into vegetative compatibility groups (VCGs) using complementation tests with nitrate non-utilizing (nit) mutants. Two California strains reported as F. oxysporum f. sp. lactucum, a type culture of F. oxysporum f. sp. lactucae, and 28 avirulent isolates of F. oxysporum obtained from crisphead lettuce were included for comparison. Among Nagano isolates, 66 isolates were identified as race 1, and 50 as race 2. Race 1 strains derived from Shiojiri and Komoro cities and race 2 from Kawakami village and Komoro city. All isolates of race 2 were biotin auxotrophs, and the race could be distinguished based on its requirement for biotin on minimal nitrate agar medium (MM). Pathogenic isolates were classified into two VCGs and three heterokaryon self-incompatible isolates. Strong correlations were found between race and VCG. All the race 1 strains were assigned to VCG 1 except self-incompatible isolates, and all the race 2 strains to VCG 2. The 28 avirulent isolates of F. oxysporum were incompatible with VCG 1 and VCG 2. California strains was vegetatively compatible with VCG 1, and they were assigned to race 1. Based on vegetative compatibility, these two races of F. oxysporum f. sp. lactucae may be genetically distinct, and F. oxysporum f. sp. lactucae race 1 is identical to F. oxysporum f. sp. lactucum. Received 7 May 2002/ Accepted in revised form 6 September 2002     

西部地区SO2总量控制指标分配合理性研究

根据国家环保局制定的《"十一五"期间全国主要污染物排放总量控制计划》中分配的西部地区SO2总量控制指标,选择与地区SO2控制指标紧密相关的评价指标,利用基尼系数法计算出各评价指标对应的基尼系数,依据基尼系数综合评价西部各地区SO2总量控制指标分配的合理性。结果表明:"计划"对西部各地区总量控制指标分配是合理的。证明基尼系数评价法对总量控制指标分配合理性研究提供了一种思路。     

In-vitro and in-vivo nematicidal activities of the cyclic dodecapeptide omphalotin A

Omphalotin A, a cyclic dodecapeptide produced by submerged cultures of the basidiomycete Omphalotus olearius, exhibited in-vitro and in-vivo nematicidal activity. Meloidogyne incognita was the most sensitive nematode. At 2.0 mg litre⁻¹, 50% of the nematodes were dead after one hour. Heterodera schachtii, Radopholus similis and Pratylenchus penetrans were affected at higher concentrations. Incorporated into agar, the compound prevented infection of cucumber seedlings by M. incognita at concentrations of 1 mg litre⁻¹ and higher. In glasshouse tests, complete protection of cucumbers and lettuce was achieved between 2.5 and 10 mg litre⁻¹. No insecticidal activity was observed when Plutella xylostella, Phaedon cochleariae or Spodoptera frugiperda were fed material containing 4 g kg⁻¹ of omphalotin A. © 1999 Society of Chemical Industry