Effect of green manure on Pythium spp. population and microbial communities in intensive cropping systems

Saprophytic soil-borne pathogens can be either actively suppressed by organic amendments or enhanced, depending on soil health conditions. This can be deleterious in the event of selection of a soil-borne population by previous soil management and short crop rotation. Trials were performed in the open field and in pots, using naturally infected soil from intensive crop systems, i.e., soil from fields with 8 years of strawberry cultivation. The aim was to study short-term response of Pythium and soil microbial populations to green manure. The use of green manure in these naturally infested soils, 3–10 weeks after fresh tissue incorporation, caused Pythium populations to increase concurrent with an increase in soil microbial populations, and did not result in the suppression of the pathogen. A more elaborate trial was performed under controlled conditions, amending soil with fresh wheat plant material, air-dried wheat plant material and an organic fertilizer with a high level of humic substances. Although compared to the original soil, all amendments caused a similar increase in organic matter content and small differences in soil respiration, incorporation of fresh, not decomposed, plant material strongly increased Pythium, while the organic fertilizer did not affect the original level of the pathogen population. The increase in total number of fungi and bacteria did not have any suppressive effect on the Pythium population in naturally infested soil used for this study.     

Microbiota in Wheat Roots Evaluated by Cloning of ITS1/2 rDNA and Sequencing

Fungi (17 species), oomycetous organisms (four species of Pythium) and a plasmodiophorid (Polymyxa graminis) were recorded in wheat roots analysed by cloning of the total ITS1/2 rDNA and sequencing of representative clones. Roots of a fourth successive wheat crop were inhabited mostly by fungal pathogens including Gaeumannomyces graminis var. tritici, Monographella nivalis var. nivalis, Ophiosphaerella sp. and Helgardia anguioides. Roots of a first wheat crop were inhabited mostly by P. graminis and saprotrophic Pythium species. Results on fungal diversity and density were compared with those obtained by pure culture isolation and morphotyping. Only M. nivalis var. nivalis and H. anguioides were identifed in wheat roots by both the molecular and the pure culture isolation methods. New and additional evidence for the ecological roles of the species recorded is discussed.     

Arbuscular Mycorrhizas, Microbial Communities, Nutrient Availability, and Soil Aggregates in Organic Tomato Production

Effects of arbuscular mycorrhzal (AM) fungi on plant growth and nutrition are well-known, but their effects on the wider soil biota are less clear. This is in part due to difficulties with establishing appropriate non-mycorrhizal controls in the field. Here we present results of a field experiment using a new approach to overcome this problem. A previously well-characterized mycorrhizal defective tomato mutant (rmc) and its mycorrhizal wildtype progenitor (76R MYC+) were grown at an organic fresh market tomato farm (Yolo County, CA). At the time of planting, root in-growth cores amended with different levels of N and P, were installed between experimental plants to study localized effects of mycorrhizal and non-mycorrhizal tomato roots on soil ecology. Whilst fruit yield and vegetative production of the two genotypes were very similar at harvest, there were large positive effects of colonization of roots by AM fungi on plant nutrient contents, especially P and Zn. The presence of roots colonized by AM fungi also resulted in improved aggregate stability by increasing the fraction of small macroaggregates, but only when N was added. Effects on the wider soil community including nematodes, fungal biomass as indicated by ergosterol, microbial biomass C, and phospholipid fatty acid (PLFA) profiles were less pronounced. Taken together, these data show that AM fungi provide important ecosystem functions in terms of plant nutrition and aggregate stability, but that a change in this one functional group had only a small effect on the wider soil biota. This indicates a high degree of stability in soil communities of this organic farm.     

Soil application of Beauveria bassiana GHA against apple sawfly,Hoplocampa testudinea (Hymenoptera: Tenthredinidae): Field mortality and fungal persistence

Low impact alternatives to synthetic insecticides for the control of apple sawfly (Hoplocampa testudinea Klug) are scarce encumbering pest management in organic apple orchards. We investigated the soil persistence and field efficacy of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (BotaniGard) against apple sawfly under common organic orchard practices. We also assessed the efficacy of B. bassiana GHA and Metarhizium brunneum Petch (indigenous strain) against sawfly in the laboratory. Larvae treated with either fungus in the laboratory died faster than control larvae and displayed 49.4%–68.4% mycosis. In the field, B. bassiana density remained high in the week after application, during larval descent to the soil. Fungal density decreased to 25% at 49 d after application and to 0.4% after 55 weeks. Molecular markers revealed that the majority of fungal isolates recovered comprised the applied B. bassiana strain GHA. Larvae pupating in soil cages in the orchard for 49 d displayed 17% mycosis. The high efficacy under laboratory conditions was not seen in the field. B. bassiana application resulted in densities above the upper natural background level during the growing season, but reversion to background levels occurred within a year. It remains to be investigated whether this has a detrimental effect on nontarget organisms. Additional work is needed to bridge the knowledge gap between laboratory and field efficacy in orchards.     

有机肥对陇东黄土旱塬冬小麦产量和土壤养分的调控效应

以冬小麦'陇鉴301'为材料,在大田条件下于2005～2008年在甘肃陇东旱塬研究了不同有机肥料对旱塬冬小麦产量、水分利用效率及土壤肥力的影响.结果表明:不同化肥有机肥料配施处理对旱塬冬小麦产量、水分利用效率和土壤养分含量有明显的调控效应,并以氮磷化肥与生物有机肥配施处理表现最佳,其籽粒产量、水分利用效率和土壤养分含量最高.与单施化肥对照相比,氮磷化肥配施生物有机肥处理3年平均籽粒产量和水分利用效率分别显著增加17.53%和16.42%,3年平均土壤有机质、全氮、碱解氮、速效磷含量分别提高11.4%、8.9%、0.2%、19.7%.因此,氮磷化肥与生物有机肥配施可以有效改善陇东黄土旱塬区农田土壤肥力,提高冬小麦水分利用效率,显著增加冬小麦产量,可能是该区农田目前最佳的施肥方式.     

多功能链霉菌生物肥对老龄梨树长势和根际与内生可培养细菌的影响

2010-2012年连续3年在河北赵县老梨区25年以上树龄梨树上进行以多功能链霉菌TOR3209为核心的生物有机肥的应用试验。结果表明, TOR3209生物有机肥能显著恢复老梨树的长势,表现为再生根和毛细根数量显著增多;叶片厚度和叶片生物量明显提高、颜色由黄转绿,叶绿素含量提高14.6%;果实品质显著改善,可溶固形物含量提高6.3%,硬度提高10.8%;根际土壤和根系内生可培养细菌多样性显著提高。表明多功能生物有机肥通过根际生态的修复改善老龄梨树的长势,在老果园改良方面具有广阔应用前景。     

土壤有机质和外源有机物对甲烷产生的影响

对土壤有机质含量及组分、外源有机物和根系分泌对甲烷产生的影响作了综述。土壤产甲烷量和甲烷排放量随有机质含量增加而提高,与土壤中易矿化有机碳或沸水浸提有机碳含量呈显著相关。外源有机碳加入促进了土壤排放甲,刺激效果与外源有机碳的用量和组成有关。还原力强的有机物如纤维素和半纤维素较还原力弱的有机物如类脂和多糖能够产生更多的甲烷。甲醇、甲基化氨基酸等无其它微生物竞争利用的有机物能被产甲烷菌更多地转化成甲烷。植物根系分泌物也促进甲烷的产生,促进作用大小与植物种类及分泌物的数量和质量有关。外源有机物通过3种方式促进土壤甲烷产生;提高土壤的甲烷底物供应量,降低土壤氧化还原电位,刺激土壤原有有机碳的转化。     

黄土高原紫穗槐丛枝菌根真菌与土壤因子和球囊霉素空间分布的关系

在黄土高原的陕西省甘泉、绥德、米脂、榆林4县(市)选取4个样地,研究紫穗槐不同深度土层丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)侵染率、孢子密度、球囊霉素和土壤因子之间的关系。结果表明:(1)AMF侵染率平均值绥德样地最大(100%),米脂样地最小(75.02%);孢子密度平均值米脂样地最大(5.91个/g),榆林样地最小(1.57个/g);4个样地孢子密度最大值均在0～10cm土层,且随土层加深而降低;AMF侵染率与孢子密度在各样地间差异显著,同一样地侵染率与孢子密度变化规律不一致。(2)榆林样地的有机碳、铵态氮、速效磷、脲酶和碱性磷酸酶活性平均值显著高于其他3个样地;除绥德、米脂样地的蔗糖酶和甘泉样地的碱性磷酸酶外,其他样地的土壤酶活性和球囊霉素含量均随土层加深而降低,且各土层之间差异显著,最大值均在0～10cm土层。(3)AMF侵染率与pH、总球囊霉素含量、易提取球囊霉素含量呈极显著正相关,与有机碳、硝态氮、速效磷含量呈显著正相关;孢子密度与速效磷、蔗糖酶、脲酶活性呈显著正相关,与铵态氮含量呈显著负相关。(4)第1、2主成分的累积方差贡献率达到56.4%,第1主成分主要综合了球囊霉素、AMF侵染率和孢子密度,第2主成分综合了pH和部分土壤因子信息。因此,球囊霉素、AMF侵染率、孢子密度、pH、部分土壤因子对决定土壤生态起主要作用。     

Production of two entomopathogenic Aspergillus species and insecticidal activity against the mosquito Culex quinquefasciatus compared to Metarhizium anisopliae

The spore productivity and insecticidal activity of two opportunistic insect pathogenic Aspergillus species (namely: Aspergillus clavatus Desmazieres and Aspergillus flavus Link (Ascomycota: Eurotiales, Trichocomaceae)) were compared to Metarhizium anisopliae sensu lato (Metchnikoff) Sorokin (Ascomycota: Hypocreales, Clavicipitaceae) for mosquito (Diptera: Culicidae) control. The production of aerial spores on wheat bran and white rice was investigated in solid-, semi-solid-, and liquid-state media supplemented with a nutritive solution. Wheat bran-based media increased the spore yield in solid-state from three to sevenfold: A. clavatus produced 48.4?±?5.2 and 15.7?±?1.6?×?10⁸ spores/g, A. flavus produced 22.3?±?4.1 and 3.1?±?2.5?×?10⁸ spores/g, and M. anisopliae produced 39.6?±?6.5 and 13.1?±?2.6?×?10⁸ spores/g of wheat bran or white rice, respectively. A. clavatus, A. flavus and M. anisopliae spores harvested from wheat bran-based solid-state media showed lethal concentrations (LC₅₀) of 1.1, 1.8, and 1.3?×?10⁸ spores/ml against Culex quinquefasciatus Say larvae in 72?h. Because A. clavatus and M. anisopliae displayed similar features when cultured under these conditions, our results suggest that insect pathogenic Aspergillus species may be as productive and virulent against mosquito larvae as a well-recognised entomopathogenic fungus.     

Biocontrol of aerial plant diseases in agriculture and horticulture: current approaches and future prospects

Until recently, the majority of research on the biological control of aerial plant diseases was focused on control of bacterial pathogens. Such research led to the commercialization of the biocontrol agent Pseudomonas fluorescens A506, as BlightBan A506™, for control of fire blight of pear. In contrast, chemical fungicides typically have provided adequate control of most foliar fungal pathogens. However, fungicide resistance problems, concerns regarding pesticide residues and revocation of registration of certain widely used fungicides have led to increased activity in the development of biocontrol agents of foliar fungal pathogens. Much of this activity has centered around the use of Trichoderma spp and Gliocladium spp to control Botrytis cinerea on grape and strawberry. The biocontrol agent Trichoderma harzianum T39 is commercially available in Israel, as Trichodex ™, for control of grey mold in grapes and may soon be registered for use in the US. Also targeted primarily against a foliar disease of grapes, in this case powdery mildew caused by Uncinula necator, is the biocontrol agent Ampelomyces quisqualis AQ10, marketed as AQ^{10  TM} biofungicide. Another promising development in the area of foliar disease control, though one which is not yet commercialized, is the use of rhizobacteria as seed treatments to induce systemic resistance in the host plant, a strategy which can protect the plant against a range of bacterial and fungal pathogens. Received 06 February 1997/ Accepted in revised form 05 June 1997     

Identification,Characterization, and Efficacy Evaluation of Bacillus velezensis for Shot-Hole Disease Biocontrol in Flowering Cherry

Though information exists regarding the pathogenesis of the shot-hole disease (SH) in flowering cherry (FC), there has been a lack of research focusing on SH management. Therefore, here, we investigated the inhibitory activities of antagonistic bacteria against SH pathogens both in vitro and in vivo as well as their biochemical characteristics and bioactive compounds. Two biosurfactant-producing bacterial antagonists, identified as Bacillus velezensis strains JCK-1618 and JCK-1696, exhibited the best effects against the growth of both bacterial and fungal SH pathogens in vitro through their cell-free culture filtrates (CFCFs). These two strains also strongly inhibited the growth of the pathogens via the action of their antimicrobial diffusible compounds and antimicrobial volatile organic compounds (VOCs). Crude enzymes, solvent extracts, and biosurfactants of the two strains exhibited antimicrobial activities. Liquid chromatography/electrospray ionization time-of-flight mass spectrometric analysis of the partially purified active fractions revealed that the two antagonists produced three cyclic lipopeptides, including iturin A, fengycin A, and surfactin, and a polyketide, oxydifficidin. In a detached leaf assay, pre-treatment and co-treatment of FC leaves with the CFCFs led to a large reduction in the severity of the leaf spots caused by Epicoccum tobaicum and Bukholderia contaminans, respectively. In addition, the two antagonists produced indole-3-acetic acid, siderophore, and a series of hydrolytic enzymes, along with the formation of a substantial biofilm. To our knowledge, this is the first report of the antimicrobial activities of the diffusible compounds and VOCs of B. velezensis against the SH pathogens and their efficiency in the biocontrol of SH.     

有机培肥和减施氮肥对小麦光合特性和氮素吸收及产量的影响

以常规单施氮肥处理为对照(CK,270kg·hm-2),设置秸秆还田(J)、秸秆还田+牛粪(JF)、秸秆还田+沼渣(JZ)3种有机培肥措施,耦合N1(较CK减量10%)、N2(较CK减量20%)和N3(较CK减量30%)3个施氮水平,采用田间试验方法,探究有机培肥和减施氮肥对小麦光合特性、氮素吸收及产量的影响。结果表明:(1)与CK相比,有机肥配施氮肥明显促进了小麦生育期分蘖的发生和有效群体数的形成,提高叶绿素含量并维持旗叶较高光合速率水平,促进小麦地上部干物质积累、植株氮素吸收,增加穗粒数和千粒重,并显著提高小麦产量,产量增幅为4.21%~17.80%,并以JFN2(JF+N2)处理组合产量最高(6 853.43kg·hm-2)。(2)同一有机肥培肥处理中,N2(减施氮肥20%)处理效果最好,能显著促进小麦群体形成,提高小麦叶绿素含量、光合速率和产量;JFN2小麦群体数在成熟期分别比JFN1、JFN3增加5.16%、4.31%,JFN2叶绿素含量在花期分别较JFN1、JFN3增加2.29%、2.31%;JFN2处理产量分别比JFN1和JFN3显著增加11.41%和7.56%。(3)同一施氮水平下,成熟期干物质积累量表现为JZN1处理显著大于JFN1和JN1处理,分别增加8.93%和12.01%;花期JF处理氮素积累量在3种施氮水平下均分别显著高于其它2种有机培肥处理;JFN2处理籽粒产量显著高于JZN2和JN2处理,增幅分别为12.17%和6.09%。研究认为,有机肥耦合施氮量可促进小麦分蘖和有效群体数的形成,提高叶绿素含量和光合速率,增加植株干物质和氮素积累,从而增加小麦产量。     

Population Dynamics of Meloidogyne incognita on Corn Grown in Soil in Fested with Arthrobotrys conoides

Microplot and greenhouse experiments were conducted to evaluate the effects of soil incorporation of the nematophagous fungus Arthrobotrys conoides and green alfalfa mulch on the population dynamics of Meloidogyne incognita on corn. Reproduction of M. incognita and the incidence of root galling were reduced by the addition of A. conoides and/or green alfalfa in all tests. Numbers of juveniles were reduced by as much as 84%, and eggs were fewest in early to mid-season soil samples from microplots. Yields increased in treatments with A. conoides and/or green alfalfa in greenhouse tests and in the microplot tests in 1979. No interaction was found between the fungus and green alfalfa in the reduction of the nematode population.     

Wheat endophytes and their potential role in managing abiotic stress under changing climate

Wheat (Triticum aestivum L.) cultivation differs considerably in respect of soil type, temperature, pH, organic matter, moisture regime, etc. Among these, rising atmospheric temperature due to global warming is most important as it affects grain yield drastically. Studies have shown that for every 1°C rise in temperature above wheat's optimal growing temperature range of 20–25°C, there is a decrease in 2.8 days and 1.5 mg in the grain filling period and kernel weight, respectively, resulting in wheat yield reduction by 4–6 quintal per hectare. Growing demand for food and multidimensional issues of global warming may further push wheat crop to heat stress environments that can substantially affect heading duration, percent grain setting, maturity duration, grain growth rate and ultimately total grain yield. Considerable genetic variation exists in wheat gene pool with respect to various attributes associated with high temperature and stress tolerance; however, only about 15% of the genetic variability could be incorporated into cultivated wheat so far. Thus, alternative strategies have to be explored and implemented for sustainable, more productive and environment friendly agriculture. One of the feasible and environment friendly option is to look at micro-organisms that reside inside the plant without adversely affecting its growth, known as ‘endophytes’, and these colonize virtually all plant organs such as roots, stems, leaves, flowers and grains. The relationship between plant and endophytes is vital to the plant health, productivity and overall survival under abiotic stress conditions. Thus, it becomes imperative to enlist the endophytes (bacterial and fungal) isolated till date from wheat cultivars, their mechanism of ingression and establishment inside plant organs, genes involved in ingression, the survival advantages they confer to the plant under abiotic stress conditions and the potential benefits of their use in sustainable wheat cultivation.     

Antifungal properties of selected lactic acid bacteria and application in the biological control of ochratoxin A producing fungi during cocoa fermentation

Thirteen Lactic acid bacteria strains isolated from fermenting cocoa and seven reference strains were used in order to assess their antifungal properties towards three ochratoxin A (OTA) producing fungi (Aspergillus carbonarius, Aspergillus niger and Aspergillus ochraceus). Furthermore, two of the isolates strains (A19 and A21) identified as belonging to the genus of Pediococcus as well as Lactobacillus plantarum B4496, Lactobacillus brevis 207 and Lactobacillus sanfranciscensis BB12 showed interesting in vitro broad antifungal activities towards the three ochratoxin-producing fungi with inhibition percentages ranging from 15% to 66.7%. Treatment of cell-free supernatant at 100°C affected antifungal activity suggesting that the main compounds responsible for this activity were of proteic nature, and hence could be bacteriocins. Application of isolate A19 in cocoa fermentation as starter inhibited the growth of each of the OTA-producing species. At the end of fermentation in boxes inoculated with A19, A. niger was not detectable while A. carbonarius concentration was found to be 2 Log CFU/g of wet beans. The assessment of the ochratoxin produced during fermentation of cocoa inoculated with A. carbonarius indicated that the use of isolate A19 as starter could reduce their level of growth so as to have only a toxin production of 0.0012 ± 0.0005 μg/kg after 40 days of storage, while this was 2.45 ± 0.35 μg/kg of fermented and dried cocoa beans in the absence of A19. This work is a contribution for the application of biological control of OTA-producing fungi during cocoa production.     

The Effect of Arthrobotrys conoides on Meloidogyne incognita Population Densities in Corn as Influenced by Temperature,Fungus Inoculum Density,and Time of Fungus Introduction in the Soil

In greenhouse experiments, the effect of Arthrobotrys conoides on Meloidogyne incognita population densities as affected by soil temperature, inoculum density, and green alfalfa was determined. The effect on M. incognita population densities was greater at a soil temperature of 25 C than at 18 or 32 C. Nematode control by A. conoides was most effective when the fungus was introduced into the soil 2 wk prior to nematode inoculation and planting of corn. Inoculum density of A. conoides was positively correlated with plant shoot weight (r = 0.81) and negatively correlated with numbers of Meloidogyne juveniles (r = -0.96), eggs (-0.89) and galls per gram of root (-0.91). A. conoides was not isolated from green alfalfa, but was isolated from alfalfa-amended soil to which no fungus had been added.     

Production and partial characterization of Duddingtonia flagrans (AC001) crude extract and its in vitro larvicidal action against trichostrongylid infective larvae

The production and partial characterization of Duddingtonia flagrans (AC001) crude extract and its in vitro larvicidal action against trichostrongylid infective larvae from sheep were studied. D. flagrans was grown in liquid medium with glucose, casein, bibasic potassium phosphate (K₂HPO₄), magnesium sulfate (MgSO₄), zinc sulfate (ZnSO₄), ferrous sulfate (FeSO₄), and copper sulfate (CuSO₄). The proteolytic activity was measured within varied pHs and temperatures. To determine the thermostability, the crude extract was incubated at 28°C for 72 h. To study the effect of different chemical compounds on the activity of the crude extract, the samples were incubated in solutions containing (10 mM): calcium chloride (CaCl₂), copper II sulfate (CuSO₄), zinc sulfate (ZnSO₄), magnesium sulfate (MgSO₄), inhibitor phenylmethylsulfonyl fluoride (PMSF), and 0.5% SDS. Results showed that the highest activity obtained (79.23 U/mL) was at pH 9.0, while the optimum temperature was 60°C (119.6 U/mL). The thermostability analysis demonstrated that after 72 h the activity was maintained or increased. It was found that the CuSO₄, ZnSO₄, and PMSF strongly inhibited the proteolytic activity. Moreover, the MgSO4 and SDS, caused a weak inhibition of the proteolytic activity. There was a significant (P<0.01) reduction in number of treated L₃ when compared to control (94.2%). The results suggest that the crude extract produced by D. flagrans (AC001) in liquid medium exerted larvicidal activity on trichostrongilid L₃ and therefore may contribute to a large-scale industrial production.     

Genotype-dependence in the interaction betweenGlomus fistulosum,Phytophthora fragariae and the wild strawberry (Fragaria vesca)

Root colonisation byGlomus fistulosum BEG 31 of a plant population from the outbreeding wild strawberry (Fragaria vesca) ranged from 42 to 80%; this was correlated with a significant increase in fruit trusses, berries and leaves. The mycorrhizal plants produced significantly more primary and secondary runners but less lateral runners. One hundred randomly selected seeds were multiplied in vitro and 4 clonal populations were selected. Root colonisation in the clones varied from 16 to 75%, with significant difference in the % colonisation between some of the clones. Percentage mycorrhizal colonisation was positively correlated with effects on host growth.The positive correlation between mycorrhizal root colonisation and growth effects in the clones was not reflected in their respective susceptibility, in the non-mycorrhizal state, toPhytophthora fragariae infection. Clones showing the highest and lowest mycorrhizal root colonisation showed high disease susceptibility whereas a clone with intermediate colonisation was resistant. When the clones were colonised with mycorrhizal fungi, the two susceptible clones became resistant toP. fragariae whereas the resistant and partially-resistant clones were less affected. Only one clone showed variation in vesicle formation when challenged withP. fragariae.     

铜、镉胁迫下施硫肥和有机肥对冬小麦碳氮运转的影响

采用盆栽试验,研究了铜、镉胁迫条件下施硫和有机肥对冬小麦碳氮运转的影响。结果表明,与各自对照相比,铜、镉胁迫下低施硫和有机肥的处理增加了小麦叶片、茎鞘、颖壳穗轴等营养器官花前贮藏物质、氮素的再运转量和运转率以及营养器官花前贮藏物质、氮素的总再运转量和总运转率,高施硫和有机肥的铜、镉处理则规律性不明显。在铜、镉胁迫条件下,施用硫肥和有机肥处理增加了小麦成熟期籽粒重和花后光合同化物输入籽粒量以及籽粒氮素含量和花后氮素积累量。与各自对照相比,铜胁迫下施硫和有机肥的处理与镉胁迫下低施硫和有机肥的处理增加了成熟期小麦的穗数、穗粒数和千粒重,提高了籽粒产量,其中以T\-5处理增产幅度最大;镉胁迫下高施硫和有机肥的处理则变化不大。铜、镉胁迫下低施硫和有机肥的处理均增加了籽粒淀粉含量,而高施硫和有机肥的铜、镉处理则未表现出此规律。此外,铜、镉胁迫下施硫和有机肥的各处理增加了籽粒蛋白质的含量。     

4种植物幼苗根茎叶及根系分泌物中低分子量有机酸的特征

该研究建立了植物根茎叶及根系分泌物中有机酸的离子色谱分析测定方法,并测定了4种不同植物幼苗根茎叶及根系分泌物中低分子量有机酸的组成,为揭示逆境胁迫下植物体内有机酸的作用提供依据。结果表明:离子色谱分析法对植物有机酸的加标回收率为91.10%~105.42%,检测限为0.12~0.36mg/L,方法线性关系良好(R2=0.965 3~0.998 8);4种植物根茎叶及根系分泌物中都可以检测出草酸、柠檬酸、苹果酸、丁二酸和酒石酸,其中草酸、柠檬酸和苹果酸为优势酸;有机酸的组成和含量具有物种以及器官的差异性;根系分泌物中的有机酸与根茎叶中有机酸的相关性也因种属差异而不同。这为研究逆境胁迫下植物器官及根系分泌物提供了可靠方法。