Entwicklung eines schnellen Bio-Tests zur Untersuchung des Wirkungs-potentials von mikrobiellen Pflanzenstärkungsmitteln

Plant-growth-promoting soil microorganisms are increasingly distributed on the world market. Nutrient mobilization, stimulation of root growth, enhanced resistance to envi-ronmental stress factors are discussed as possible mechanisms. These assumptions are based only on scarce scientific evidence due to limited reproducibility of pot and field experiments, limited information concerning the conditions for successful applica-tion, limited standardization of inoculum preparation and quality. Thus, the develop-ment of rapid screening tests is to demonstrate the principle effectiveness of biofertil-izers prior to set-up of labourous pot or field experiments is urgently required. In this study, a rapid bio-test with cucumber (Cucumis sativa L.) as an indicator plant was developed to evaluate the effectiveness of five commercial biofertilizers based on Trichoderma spp. and Bacillus spp. (Biohealth-G, Biohealth-WSG, Biomex, Vitalin T50 and SP11) using germination rate, root and shoot biomass, maximum root length, and leaf area as test parameters. The experiment was repeated twice with 6 replicates in hydroponic culture under controlled conditions (pH 5.5, 22° C; Light: 230 mmol cm2 sec-1). Biofertilizers were applied at the rate of 3 g per 2.5 l mineral nutrient solution. Germination rate was increased by 20 - 25% in all biofertilizer treatments compared to the control. After 2 weeks culture period, root dry weight and leaf area of Biohealth-G, Vitalin T50, SP-11 and Biomex-treated cucumber seedlings were significantly in-creased. Biohealth-G and Vitalin T50 showed significantly higher main root length and Biohealth-G higher shoot dry weight than the remaining treatments, while Biohealth-WSG did not cause differences compared to untreated control plants. The pathogen-antagonistic potential of Trichoderma strains can be easily tested by co-inoculation with the pathogenic fungus Gaeumannomyces graminis on malt extract peptone agar plates. The results suggest that the activity potential of different Trichoderma-based biofertilizers could be easily screened by using the described bio-test with cucumber seedlings

Glyphosate-induced impairment of plant growth and micronutrient status in glyphosate-resistant soybean (Glycine max L.)

This investigation demonstrated potential detrimental side effects of glyphosate on plant growth and micronutrient (Mn, Zn) status of a glyphosate-resistant (GR) soybean variety (Glycine max cv. Valiosa), which were found to be highly dependent on the selected growth conditions. In hydroponic experiments with sufficient Mn supply [0.5 μM], the GR cv. Valiosa produced similar plant biomass, root length and number of lateral roots in the control treatment without glyphosate as compared to its non-GR parental line cv. Conquista. However, this was associated with 50% lower Mn shoot concentrations in cv. Conquista, suggesting a higher Mn demand of the transgenic cv. Valiosa under the selected growth conditions. Glyphosate application significantly inhibited root biomass production, root elongation, and lateral root formation of the GR line, associated with a 50% reduction of Mn shoot concentrations. Interestingly, no comparable effects were detectable at low Mn supply [0.1 μM]. This may indicate Mn-dependent differences in the intracellular transformation of glyphosate to the toxic metabolite aminomethylphosphonic acid (AMPA) in the two isolines. In soil culture experiments conducted on a calcareous loess sub-soil of a Luvisol (pH 7.6) and a highly weathered Arenosol (pH 4.5), shoot biomass production and Zn leaf concentrations of the GR-variety were affected by glyphosate applications on the Arenosol but not on the calcareous Loess sub-soil. Analysis of micronutrient levels in high and low molecular weight (LMW) fractions (80% ethanol extracts) of young leaves revealed no indications for internal immobilization of micronutrients (Mn, Zn, Fe) by excessive complexation with glyphosate in the LMW phase

Effect of bicarbonate on uptake and translocation of 59Fe in two grapevine rootstocks differing in their resistance to Fe deficiency chlorosis

In order to study the effect of high bicarbonate concentration in the root medium on root FeIII reduction, Fe uptake and its translocation to the leaves, two rootstocks (Vitis riparia Michx., susceptible, and 41 B (Vitis vinifera L. cv. Chasselas x Vitis berlandieri Planch.), resistant to Fe deficiency chlorosis) were pre-cultivated in nutrient solutions with high and low Fe supply. After three weeks of preculture at low Fe, chlorosis symptoms occurred in both, Fe-resistant and Fe-susceptible genotypes. The FeIII reducing capacity by roots was enhanced at Fe deficiency in both genotypes, which was consistent with the increase of subsequent root uptake and translocation rates of 59Fe. In the presence of bicarbonate in the solutions the FeIII reducing capacity, 59Fe uptake and translocation rate decreased in both genotypes precultured with low re supply. The 59Fe uptake and translocation rate, however, were significantly higher in the Fe chlorosis-resistant rootstock 41 B. These results clearly indicate that bicarbonate-induced Fe chlorosis in grapevine rootstocks is obviously caused by an inhibition of Fe uptake and translocation due to an inhibition of FeIII reduction by root cells. The fact that these processes were less inhibited in the chlorosis-resistant rootstock hints to genotypical differences in Fe acquisition by roots at high bicarbonate levels. These differences might be used in breeding programs to identify Fe chlorosis-resistant rootstocks

High-current Capability of Coaxial Cables in Magnetoforming Applications

Magnetoforming technology often requires impulse current amplitudes of several hundred kiloamps, at pulse durations between 30 µs and > 100 µs. Often, it is required to provide the impulse via a flexible transmission line (cable) in order to allow the forming coil to be positioned correctly. These cables have to withstand the high pulse currents without deterioration for a large number of pulses. In addition, it is necessary to minimise the inductance of the cable connection, as an increase in inductance negatively influences the efficiency of the installation as a whole, whence low-inductance coaxial cables are required which are able to fulfil all of these requirements simultaneously. Manufacturers normally do not specify the impulse current capability of coaxial cables, as this is not necessary for most standard applications. Therefore, experiments were performed to explore the limits of commercial medium high voltage cables in regard of their impulse current withstand capability for these specific impulse parameters. A coaxial medium voltage cable has been tested at single pulses of ca. 100 µs duration, at amplitudes between 30 and 140 kA. The radial deformation (expansion) of the cable was detected with a high-resolution, high-speed camera. At a frame rate of 9000 frames/s the expansion of the cable has been determined as a function of the current amplitude. We observed dynamic changes of the cable diameter at currents above 81 kA, reaching up to 1.26 mm increase in diameter at 142 kA pulse amplitude. Above 100 kA, part of the deformation becomes irreversible, with cumulated permanent changes of up to 1 mm. The measurements are used to estimate the operating range of these cables

A 100 kJ Pulse Unit for Electromagnetic Forming of Large Area Sheet Metals

Magnetoforming of tube or sheet metal parts can significantly extend the range of geometries conceivable with state-of-the-art forming methods. A major advantage is the considerably higher forming speed of the process achievable by using a magnetic piston without inertia. Key for this technology is the development of reliable, long-lifetime, high current pulse power generators able to deliver tens to hundreds of kiloamps of peak current to a mainly inductive load which is highly variable in time during the forming process. A high-current, high energy pulse generator for electromagnetic forming of large area sheet metal has been developed and was taken into operation. Design criteria were reliability and safety for all possible load cases, including short circuits and short-circuiting loads under operation, at nominal peak currents of up to 200 kA and peak pulse energies of up to 100 kJ. In order to comply with the safety requirements, an all-solid-state design has been chosen using high power semiconductor switches for pulse forming instead of ignitrons or spark gaps. Due to constraints concerning space and manageability, the coupling between the load and the pulse forming unit is achieved via a semi-rigid bundle of high voltage cables, allowing an adjustment of the carrier of the forming coil while being electrically connected to each other. We report on the development of a pulse generator for peak currents of 50 kA to up to 200 kA at a pulse width of typically around 100 µs, depending on the load parameters. In order to meet lifetime requirements suitable for industrial applications, the short circuit handling capability of peak currents of up to 450 kA is a major issue in the pulse generator design. A modular 3-branch design of parallel capacitor banks has been adopted to achieve the requirements concerning reliability, lifetime, and short circuit handling. The prototype pulse generator is based upon off-the-shelf devices, including high-current semiconductor switches. First operating results of the commissioning phase of the installation are reported

Physical Mapping of Micronutritional Genes in Wheat-rye Translocations

In rye (Secale cereale L.), there are loci on chromosome arm 5RL which give rise to increased copper (Cu)- and iron (Fe)-efficiency, respectively. Four different wheat-rye translocations each harboring a terminal segment of different size of the rye chromosome arm 5RL were identified by test crosses and Giemsa-banding: \u27T29\u27 (5AS.5RL), \u27T63\u27 (5BS.5BL-5RL), \u27Vhn\u27 (4BS.4BL-5RL) and \u27Cor\u27 (4BS.4BL-5RL). The translocation break points were detected by chromosome painting technique GISH and the sizes of the rye chromosome segments involved were determined by computer image analysis. The Cu-efficiency gene Ce was physically mapped to the terminal region of 5RL, and the genes for mugineic acid and for hydroxymugineic acid synthetases involved in the strategy II of Fe-efficiency control to two intercalary regions of 5RL. In all wheat-rye translocation lines the Ce gene is linked to the dominant hairy neck character (HaI) from rye. This morphological trait and the RFLP probe \u27WG 199\u27 as well can serve as proper markers for a marker-based large-scale selection in wheat breeding

Glyphosate inhibition of ferric reductase activity in iron deficient sunflower roots

Iron (Fe) deficiency is increasingly being observed in cropping systems with frequent glyphosate applications. A likely reason for this is that glyphosate interferes with root uptake of Fe by inhibiting ferric reductase in roots required for Fe acquisition by dicot and nongrass species. This study investigated the role of drift rates of glyphosate (0.32, 0.95 or 1.89 mM glyphosate corresponding to 1, 3 and 6% of the recommended herbicidal dose, respectively) on ferric reductase activity of sunflower (Helianthus annuus) roots grown under Fe deficiency conditions. Application of 1.89 mM glyphosate resulted in almost 50% inhibition of ferric reductase within 6 h and complete inhibition 24 h after the treatment. Even at lower rates of glyphosate (e.g. 0.32 mM and 0.95 mM), ferric reductase was inhibited. Soluble sugar concentration and the NAD(P)H oxidizing capacity of apical roots were not decreased by the glyphosate applications. To our knowledge, this is the first study reporting the effects of glyphosate on ferric reductase activity. The nature of the inhibitory effect of glyphosate on ferric reductase could not be identified. Impaired ferric reductase could be a major reason for the increasingly observed Fe deficiency in cropping systems associated with widespread glyphosate usage

Untersuchungen zur Wirkung einer einmalig variierten Bodenbearbeitung auf Ertragsbildung, Verunkrautung und Nitratauswaschung unter den Produktionsbedingungen des Ökologischen Landbaus

Einleitung Nitrat als Pflanzennährstoff trägt zu erheblichen Belastungen des Trinkwassers in vielen landwirtschaftlich genutzten Wassereinzugsgebieten bei. Eine Reduzierung dieser Nitratausträge von Seiten der Landwirtschaft gestaltet sich durch komplexe Zusammenhänge von Standortfaktoren, Bewirtschaftungsweisen und unterschiedlichen Düngungstechniken sehr schwierig. Der Ökologische Landbau stellt eine Bewirtschaftungsweise dar, die gänzlich auf den Einsatz chemisch-synthetischer Pflanzenschutzmittel verzichtet, doch Austräge von Nitrat mit dem Sickerwasser sind auch hier zu finden. Die Neufassung der Schutz-und Ausgleichsverordnung (SchALVO), verabschiedet im Februar 2002, ist darauf ausgerichtet, Nitratausträge von landwirtschaftlich genutzten Flächen durch gezielte pflanzenbauliche Maßnahmen (Begrünung über Winter, pfluglose Bearbeitung zu Wintergetreide nach N-intensiven Vorfrüchten) auf einem möglichst niedrigen Niveau zu halten. Für ökologisch wirtschaftende Betriebe ist eine zeit- und bedarfsgerechte Bodenbearbeitung oft nicht einzuhalten. Dies kann Probleme sowohl in der Unkrautkontrolle als auch in der Schädlingsbekämpfung mit sich bringen. Ziel der Untersuchung ist es, zu überprüfen, ob bestimmte Verfahren der Bodenbearbeitung tatsächlich zu erhöhten N-Austrägen führen und ob die in der SchALVO genannten pflanzenbaulichen Maßnahmen zu einer Beeinträchtigung der Anbauverfahren im Ökologischen Landbau führen

Beziehungen zwischen Chlorosegrad, Eisengehalten und Blattwachstum von Weinreben auf verschiedenen Standorten

Relationship between chlorosis, iron and leaf growth in grapevines growing at different locationsAt different locations, samples from chlorotic and green leaves were taken periodically during the growing season. Leaf area, contents of chlorophyll, total iron and acid-soluble iron were determined in leaf samples from various positions within the shoots. At locations where chlorosis became evident during the growth period, analysis showed that these leaves had lower levels of both total iron and acid-soluble iron compared with leaves of locations without chlorosis. At all locations, a close linear correlation was found between the contents of acid-soluble iron and chlorophyll. For total iron this positive correlation was confined to the lower concentration range (50-90 μg Feig dry weight). The highest and lowest contents of total iron and of acid-soluble iron were found in the youngest leaves and in the leaves with the largest growth rate, respectively. This demonstrates 'dilution' and 'concentration' effects of iron in the leaf dry matter. Therefore, particular care is necessary in leaf sampling as a basis for causal interpretations of iron chlorosis.The results of the present study indicate that the lower uptake and translocation rates of iron rather than the 'inactivation' of iron within the shoots are responsible for chloros is at the various locations

Einfluss unterschiedlicher Inokulationstiefen mit dem arbuskulären Mykorrhizapilz Glomus mosseae auf die Mykorrhizierung bei Reben (Vitis sp.) in Wurzelbeobachtungskästen

In einem Gefäßversuch mit Grünstecklingen der Unterlagssorte SO 4 (Vitis berlandieri x Vitis riparia) wurde der Einfluss einer unterschiedlichen Bandinokulation mit dem AM-Pilz Glomus mosseae (Nicol. et Gerd.) Gerdemann et Trappe auf die Entwicklung des Pilzes innerhalb des Wurzelsystems untersucht. Hierbei wurde in 70 cm tiefe Wurzelbeobachtungskästen mit einem P-armen, sterilisierten Rebschulboden in eine Tiefe von 9-18 cm bzw. 36-45 cm eine 9 cm dicke Inokulationsschicht eingebracht. Im unmittelbaren Inokulationsbereich war bei beiden Inokulationsvarianten mit 45 bzw. 35% der AM-Infektionsgrad am höchsten. Mit zunehmendem Abstand vom Inokulationsband waren die Rebwurzeln geringer mykorrhiziert bzw. es konnte keine AM-Infektion festgestellt werden. Durch die Inokulation im oberen Bodenbereich wurden Trockengewicht und P-Gehalt der SO 4-Stecklinge erhöht. Die Zn-Gehalte in den Blattspreiten waren bei beiden Inokulationsmethoden erhöht, der Cu-Gehalt bei Inokulation des unteren Bodenbereichs. Bereits eine Teilbesiedlung des Wurzelsystems mit AM führte zu ausreichenden Inokulationserfolgen in Form von erhöhten Nährstoffgehalten in den Blättern und erhöhter Trockensubstanzbildung. Die Inokulation in der größeren Bodentiefe (36-45 cm) führte zu einer verzögerten Mykorrhizierung der Wurzeln, so dass möglicherweise die positiven Effekte des AM-Pilzes bei dieser Inokulationsmethode nicht zum Tragen kamen.Influence of different inoculum places of the mycorrhizal fungus Glomus mosseae on mycorrhizal colonization in grapevine rootstocks (Vitis sp.)Grapevine rootstocks (Vitis berlandieri x Vitis riparia, cv. SO 4) were grown in pots with sterilised soil with low P level from a nursery to test the effect of a local supply of inoculum of an arbuscular mycorrhizal fungus (Glomus mosseae [Nicol. et Gerd.] Gerdemann et Trappe) on mycorrhizal colonization of the root system. The inoculum was placed in a 9-cm deep band either in 9-18 cm or in 36-45 cm soil depths. After 6 weeks of growth, mycorrhizal colonisation of roots was highest in the inoculated soil zone. With increasing distance from the inoculum band, mycorrhizal colonization decreased or was absent. When the inoculum was placed in the top soil, the shoot dry weight and the leaf blade Zn and P concentrations significantly increased in mycorrhizal as compared to nonmycorrhizal plants. When the inoculum was placed in 36-45 cm soil depth, leaf blade Zn and Cu concentrations increased in mycorrhizal plants, but shoot dry weight was not affected. In conclusion, a locally restricted mycorrhizal colonization of the root system was sufficient to increase growth and nutrient uptake of grape rootstocks