Effect of essential oils on the growth of Fusarium verticillioides and fumonisin contamination in corn

Essential oils extracted by hydrodistillation from local plants in Benin, western Africa, and oil from seeds of the neem tree (Azadirachta indica) were evaluated in vitro and in vivo for their efficacy against Fusarium verticillioides infection and fumonisin contamination. Fumonisin in corn was quantified using a fluorometer and the Vicam method. Oils from Cymbopogon citratus, Ocimum basilicum, and Ocimum gratissimum were the most effective in vitro, completely inhibiting the growth of F. verticillioides at lower concentrations over 21 days of incubation. These oils reduced the incidence of F. verticillioides in corn and totally inhibited fungal growth at concentrations of 8, 6.4, and 4.8 microL/g, respectively, over 21 days. At the concentration of 4.8 microL/g, these oils did not affect significantly fumonisin production. However, a marked reduction of fumonisin level was observed in corn stored in closed conditions. The oils adversely affected kernel germination at 4.8 microL/g and therefore cannot be recommended for controlling F. verticillioides on stored corn used as seeds, when used at this concentration. The oil of neem seeds showed no inhibitory effect but rather accelerated the growth of F. verticillioides.     

A classification scheme for earthworm populations (Lumbricidae) in cultivated agricultural soils in Brandenburg,Germany

Earthworm activity is observed at long‐term monitoring sites as an indicator of soil function to assess changes resulting from environmental and management conditions. In order to assess changes, characteristic values of earthworm populations under different site conditions have to be known. Therefore, a classification scheme for site‐specific earthworm populations was developed for soil in agricultural use, taking interactions between earthworm populations and soil properties into account. Characteristics of sites grouped by means of a cluster analysis after principal‐component analysis served as a basis for the derivation of the classification scheme. Soil variables found to characterize site differences with respect to earthworm populations were the texture of the topsoil, the texture of the subsoil, and the soil organic‐matter (SOM) content. The textural classes of the topsoil were divided into five groups comprising sandy soils (Ss), silty sand soils (Su), slightly loamy sand soils (Sl2), medium to strongly loamy sand soils (Sl3/Sl4), and loam and clay soils. Soil organic matter was divided into grades of equal size in a range from <1%, 1%–2% up to >6%. The variables “earthworm abundance” and “earthworm species” were selected to represent earthworm populations and were divided into six groups ranging from very low to extremely high. Defined groups of earthworm populations showed a clear structure in relation to soil textural groups and the content of SOM. From this distribution, a classification scheme was derived as basis for prognostic values of site‐specific earthworm populations, thus enabling the interpretation of changes over time. For some soil textural groups, selected variables appeared to enable the derivations of expected earthworm densities and species composition outside the range of the given database, but for some soil textural groups, broader databases will be needed to specify these derivations.     

A simulation study on tests of hypotheses and confidence intervals for fixed effects in mixed models for blocked experiments with missing data

This article considers the analysis of experiments with missing data from various experimental designs frequently used in agricultural research (randomized complete blocks, split plots, strip plots). We investigate the small sample properties of REML-based Wald-type F tests using linear mixed models. Several methods for approximating the denominator degrees of freedom are employed, all of which are available with the MIXED procedure of the SAS System (8.02). The simulation results show that the Kenward-Roger method provides the best control of the Type I error rate and is not inferior to other methods in terms of power.     

Entwicklung der Niederschlags-Deposition von Schwermetallen in Westdeutschland. 2. Arsen,Chrom, Kobalt und Nickel

Development of heavy-metal deposition by precipitation in West Germany. 2. Arsenic, chromium, cobalt, and nickel Between 1984 and 1993 the deposition of As, Cr, Co and Ni with bulk precipitation was measured on 6 open field sites in Northrhine-Westphalia/Germany. The absolute amount of As, Cr, Co and Ni deposition varies according to field sites and annual precipitation. In all studied areas, however, As deposition with bulk precipitation decreased significantly during the observation period. Considering all research stations under study, the average As deposition fell from 11.0 g ha^?1 in 1984 to 3.0 g ha^?1 (r = ?0.982***). The reduction in As deposition corresponds with the reduction in As emission within the same period of time prognosticated. Immission of Cr and Co also decreased significantly over the majority of the studied areas. The avarage Cr immission fell from 8.5 g ha^?1 in 1984 to 3.5 g ha^?1 in 1993 (r = ?0.888***), whereas the average Co immission decreased from 2.6 g ha^?1 to 1.1 g ha^?1 (r = ?0.869***). In contrast, no reduction in Ni deposition with precipitation was found on any of the studied areas under observation. Co shows the lowest deposition rates. On average, 2.2 times as much Cd, 2.7 times as much As, 3.2 times as much Cr, 6.5 times as much Ni, and 66 times as much Pb was deposited on the six open field sites in Northrhine-Westphalia in 1993.     

Taxonomy and evolution of cultivated plants: Literature review 1982/1983

Summary Important papers on taxonomy and evolution of cultivated plants published in 1982 and 1983 were compiled and briefly discussed.

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Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1982/1983

Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1982 und 1983 wurden zusammengestellt und kurz kommentiert.

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: 1982–1983

, 1982 1983 . .

     

Retention of Ni,Zn and Cd by Si-associated goethite

Synthetic goethite used to study the effects of reaction time and temperature on the pH-dependent sorption of Ni, Zn and Cd was associated with amorphous silica. Ni interacted with dissolved Si and formed a Ni/Si precipitate on the goethite surface. Individual metals added at a concentration of 0.5 μmol g^?1 and sorbed during a reaction period of 504 hours (21 days) at 35°C were extracted by 0.7 M HNO₃ for 14 days. At the end of this period 11,28 and 40 percent of Ni, Cd and Zn, respectively, were not extracted whereas 20 percent of the total Fe content of the goethite and 39 percent of the associated Si were dissolved. During the sorption process metals became immobilized in the goethite particles. This effect can be related to a diffusion of metal ions into micropores. A total mobilization of sorbed metals can only be achieved by a complete dissolution of the goethite. The strong fixation of Ni, Zn and Cd by goethite suggests that additions of this Fe oxide could be used to ameliorate highly contaminated sludges or soils.     

The effect of mulching and tillage on the water and temperature regimes of a loess soil: Experimental findings and modeling

Crop residues and tillage are being advocated for their potential effectiveness to modify the soil hydrothermal regime. This study was carried out to quantify the effect of straw mulching and rotary hoeing on the soil water and thermal regimes of a loess soil. The field experiment consisted of four treatments: (1) no mulching and no rotary hoeing as control, (2) rotary hoeing, (3) wheat straw mulching, and (4) wheat straw mulching with rotary hoeing. During the study period from 5 August to 20 September 2002, soil water content and pressure head were measured daily at five soil depths (0.05, 0.15, 0.30, 0.45 and 0.60 m). Soil temperatures were measured at hourly resolution at three depths (0.05, 0.15 and 0.30 m). Mulching decreased soil water loss on an average by 0.39 mm d⁻¹ and rotary hoeing increased water loss on an average by 0.12 mm d⁻¹ as compared to control. Volumetric soil water contents at pF 1, 1.8 and 2.5 up to 30 cm depth were highest (0.418, 0.390, and 0.360 m³ m⁻³, respectively) with the application of wheat straw mulch and lowest (0.393, 0.363, and 0.333 m³ m⁻³, respectively) with the rotary hoeing. Soil thermal conductivity measured at pF 1, 1.8, 2.5, 3, and 3.7 decreased with increasing suctions in all the treatments. However, the tillage and mulching did not affect the soil thermal conductivity. Further, compared with the control, mulching reduced average soil temperatures by 0.74, 0.66, 0.58 °C at 0.05, 0.15, and 0.30 m, respectively, during the study period. The rotary hoeing tillage slightly increased the average soil temperature by 0.21 °C at 0.05 m depth compared to control. The tillage effect did not transmit to deeper depths. The numerical model Hydrus-1D was used to simulate the water and temperature regimes of the treatments. Simulations with hydraulic parameters derived from laboratory measurements did not yield satisfactory results. Only when the hydraulic parameters were optimized by the inverse method, simulations performed well. The largest deviations were observed in the wheat straw mulching treatment. Simulations were further improved by adjusting the potential evaporation rate from the measured data which was achieved by linking the inversion code UCODE to the Hydrus-1D. Soil temperatures at 0.05 and 0.15 m in all the treatments were modeled well, yielding root mean square errors between 0.3 and 1.7 °C. As for soil water, the largest temperature deviations were found for the mulching treatment. All simulations underestimated soil temperatures at 0.30 m. In conclusion, crop residue can be utilized as mulching to improve the soil hydrothermal regime and the Hydrus-1D model can be used as a tool for analyzing water and heat transport processes and for estimating hydraulic transport parameters under field conditions.     

Managing contaminated sediments

While remediation and storage of contaminated dredged materials is a key issue at harbour sites, there is another type of sediment pollution problem, which mainly originates from large-scale dispersion of contaminants in flood-plains, dike foreshores and polder areas. In recent years, catastrophic cases of sediment contaminations have occurred in connection with the failure of tailing dams from mines. Unlike problems related to conventional polluted sites, the risks here are primarily connected with the transporting and depositing of contaminated solids in a catchment area, especially in downstream regions. A special example demonstrating the dispersion of highly contaminated sediments in a large catchment area will be shown from the so-called Chemistry Triangle of the upper Elbe River system, Germany. The Spittelwasser area, situated there, was chosen by the organisers of the international conference ConSoil 2000 for a case comparison and four expert teams from Denmark, Germany, the Netherlands and the UK were invited to participate in this Case Study. Evaluation of the plan was done by members of the networks of NICOLE (Network for Industrially Contaminated Land) and CLARINET (Contaminated Land Rehabilition Network). In the study of the German team, five major groups of technical measures have been identified by the environmental authorities to be discussed in relation to the Spittelwasser case or for similar problem solutions in contaminated flood-plain areas. The team came to the conclusion that none of these techniques would be applicable as an individual measure. Instead, a stepwise approach combining different monitoring techniques and remediation measures was proposed. These would include point excavations of critical material, promotion of plant growth as an element for stabilising the soil and flood sediments, as well as the installation of sediment traps. At the Spittelwasser site, investigations are planned on the effects of natural attenuation processes of organic and inorganic contaminants in flood-plain sediments and soils. In the practice of this concept, non-destructive, ‘intrinsic’ bonding mechanisms and their temporal development have thus far found much less recognition compared to destructive processes such as biological degradation. Yet these so-called ‘diagenetic’ effects, which apart from chemical processes involve an enhanced mechanical consolidation of soil and sediment components by compaction, loss of water, and mineral precipitations in the pore space, may induce a quite essential reduction of the reactivity of solid matrices [see Part I ‘Improving Chemical and Biological Criteria’ (JSS - Journal of Soils and Sediments, Vol 1, No 1, pp 30-36)]. Part IV ‘Subaqueous Storage/Capping of Dredged Material’ will be published in JSS No. 4 (December issue).     

Rasterelektronenmikroskopische Untersuchungen an Samen der GattungAllium L. III.

Zusammenfassung Die Testa-Epidermisskulpturen von weiteren Arten der GattungAllium L. wurden rasterelektronenmikroskopisch untersucht. Dabei konnten die bisherigen Befunde über die sektionsspezifische Ausbildung der Testaskulpturen weitgehend bestätigt werden.Die wenig differenzierten Testaskulpturen der sect.Anguinum G. Don exKoch wurden an weiteren Arten der Gattung nachgewiesen. Die untersuchten Arten der sect.Rhizirideum G. Don exKoch entsprechen in der Mehrzahl den charakteristischen granulösen Skulpturtypen dieser Sektion. Besonderheiten ergeben sich bei einzelnen Arten durch spezielle verrucose Skulpturen bzw. deutlich undulierte Antiklinalwände.Die Testaskulpturen einiger Arten der sect.Cepa (Miller)Prokh. konnten den für diese Sektion typischen Skulpturformen zugeordnet werden.Der einheitliche, verrucose Skulpturtyp der sect.Codonoprasum Reichenb. wurde durch weitere Arten bestätigt. Ebenso zeigen die Arten der sect.Caloscordum (Herb.)Bak. übereinstimmende Testamerkmale.Die untersuchten Sippen der sect.Lophioprason Traub entsprechen in ihrer Testaskulptur dem bisher bekannten Merkmalsspektrum der jeweiligen Artengruppe. Hierbei konnte auch der spezielle verrucose Skulpturtyp derAllium acuminatum-Gruppe an weiteren Arten dieser Gruppe nachgewiesen werden. Granulöse Skulpturformen wurden bei einzelnen Arten der sect.Rhophetoprason Traub und sect.Amerallium Traub gefunden.Die der sect.Allium L. und dem subgen.Melanocrommyum (Webb etBerth.)Rouy gemeinsame Testaform, die durch verrucose Skulpturen sowie eine ausgeprägte Antiklinalwand-Undulation gekennzeichnet ist, wurde durch weitere Arten dieses Verwandtschaftskreises bestätigt. Dabei unterscheidet sich der Undulationstyp der SektionenAllium L. undMegaloprason Wendelbo von den untersuchten Arten anderer Sektionen des subgen.Melanocrommyum (Webb etBerth.)Rouy.

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SEM investigations on seeds of the genusAllium L. III

Summary The structure of the testa epidermis of additional species ofAllium L. have been studied by means of SEM. Results obtained earlier for different sections of the genus could be confirmed:The less differentiated testa structure of sect.Anguinum G. Don exKoch has been observed in further species of this group.Most of the newly examined taxa of sect.Rhizirideum G. Don exKoch correspond to the already known testa types of this section and are characterized by granulate seed coat surfaces. Deviations have been found in some species which possess either a special type of verrucate sculptures or have distinctly undulated anticlinal walls of the testa cells.The earlier described two testa types of sect.Cepa (Mill.)Prokh. could be observed in some additional species of this section, too.Likewise the uniformly verrucate sculptures of sect.Codonoprasum Rchb. have been found in further species and also the taxa of sect.Caloscordum (Herb.)Bak. agree in their testa characters.Earlier described seed coat types for different species groups of sect.Lophioprason Traub could be confirmed, among them the verrucate sculptures of theAllium acuminatum-group. Granulate testa surfaces have been analyzed in several species of sect.Rhophetoprason Traub and sect.Amerallium Traub. The testa type commonly found in sect.Allium as well as in subgen.Melanocrommyum (Webb etBerth.)Rouy and characterized by verrucate sculptures and strong undulation of the anticlinal cell walls could be observed in further species of these infrageneric groups. The undulation pattern of sect.Allium and sect.Megaloprason Wendelbo however differs from that of other sections of subgen.Melanocrommyum (Webb etBerth.)Rouy.

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Allium L. . III.

Allium L. . , - . Anguinum G. Don exKoch . Rhizirideum G. Don exKoch , . . Cepa (Miller)Prokh. . Codonoprasum Reichenb. . Caloscordum (Herb.)Bak. . Lophioprason Traub , . , Allium acuminatum- . Rhophctoprason Traub Amerallium Traub. Allium L. Melanocrommyum (Webb et.Berth.)Rouy, , , . Allium L. Megaloprason Wendelbo Melanocrommyum (Webb etBerth.)Rouy.

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Einige der untersuchten Arten konnten während der gemeinsamen Expeditionen in der Georgischen SSR gesammelt werden, die von Frau Dr.R. K. Beridze, Botanisches Institut der Georgischen Akademie der Wissenschaften, in bewährter Weise organisiert wurden. Dieses ist eine willkommene Gelegenheit, ihr diesen Beitrag anläßlich ihres 70. Geburtstages zu widmen.