Induced resistance in tomato plants against Fusarium wilt invoked by Fusarium oxysporum f.sp. dianthi     

B. A. M. Kroon  R. J. Scheffer  D. M. Elgersma 《European journal of plant pathology / European Foundation for Plant Pathology》1991,97(6):401-408

Tomato plants, susceptible toFusarium oxysporum f. sp.lycopersici, were inoculated by immersing the roots in a conidial suspension ofF. oxysporum f. sp.lycopersici race 1,F. oxysporum f. sp.dianthi race 2 or a mixture of both fungi. Plants inoculated withF. oxysporum f. sp.lycopersici showed disease symptoms after 2 weeks, whereas plants inoculated withF. oxysporum f. sp.dianthi or a mixture of both fungi remained symptomless for over 7 weeks, the duration of the experiment. In another experiment root systems of plants were split and each half was separately inoculated. One half was firstly inoculated withF. oxysporum f. sp.dianthi or treated with water, followed after a week by a second inoculation of the other half withF. oxysporum f. sp.lycopersici or by a water treatment. The disease symptoms in the half firstly inoculated withF. oxysporum f. sp.dianthi were significantly delayed, compared to plants of which that half had been treated with water. BecauseF. oxysporum f. sp.dianthi reduced disease symptoms caused byF. oxysporum f. sp.lycopersici without any direct interaction with this pathogen, it is concluded thatF. oxysporum f. sp.dianthi is able to induce resistance againstF. oxysporum f. sp.lycopersici in tomato plants.  相似文献   

Effects of crushed conspecifics on growth and survival of Penaeus monodon Fabricius post larvae     

Bui Tui Nga  Miquel Lürling  Edwin Peeters  Rudil Roijackers  Marten Scheffer  & Truong Trong Nghia 《Aquaculture Research》2006,37(3):224-232

In the present study, the hypothesis tested was that Penaeus monodon post‐larvae (PL) experience lower growth when exposed to crushed conspecifics, which was achieved by exposing individual P. monodon PL with abundant food for 4 weeks to a gradient from 0 to 100 crushed conspecific PL L^?1. Both dry weight (48.5±7.2 mg) and body size (28.0±1.3 mm) of animals exposed to 1 macerated PL L^?1 were significantly (P≤0.011) higher than those of animals in treatments with 0, 5 and 10 crushed PL L^?1 (average over treatments: 25.6±3.2 mg; 23.4±0.5 mm). All animals died within 1 week when exposed to 70 and 100 crushed PL L^?1, and within 3–4 weeks when exposed to 50 and 30 crushed PL L^?1. Exposure time affected mortality and it appeared that LC₅₀ values decreased from 60 to 13 crushed PL L^?1 from 1 to 4 weeks' exposure. Survival of P. monodon PL was negatively correlated to pH, biological oxygen demand, ammonia and nitrate. In conclusion, low dose of crushed conspecifics has a stimulatory effect on P. monodon PL, as larvae were heavier and larger, while high doses cause high mortality.  相似文献   

Die Phosphatmobilität im Hochmoorboden in Abhängigkeit von der Düngung     

H. Kuntze  B. Scheffer 《植物养料与土壤学杂志》1979,142(2):155-168

Phosphate mobility in relation to fertilizing effects in raised-bog peat The phosphate solubility of raised-bog peat soils is very different from the phosphate solubility of mineral soils. Compared to mineral soils the losses of phosphates by leaching are 10 to 20 times higher. This mobility of phosphates is destined by the quantity, kind and time of fertilizing, land use (grassland or arable land) and fertilizing technique. Field and lysimeter trials with raised-bog peat soils show: 1. Water soluble phosphates are quickly translocated and leached. 2. Water insoluble phosphates are quickly solved and leached in raised-bog peat soils. The mobility of the phosphates decreases with increasing pH-value of the top soil and topdressing. At a pH-value of 4,O nearly 80% of Thomasphosphat and nearly 70% of Hyperphos phosphates are leached in lysimeter trials; at pH-value of 4 3 only 17 % of Thomasphosphat and 15 % of Hyperphos phosphates are leached. 3. To minimize leaching losses phosphate fertilizingin spring is recommended to reduce the phosphate leaching. 4. The phosphate leaching in grassland is twice or thrice less than in arable land.  相似文献   

Phosphoraustrag aus Niedermoorböden - Ergebnisse eines Lysimeterversuches ohne Pflanzenbewuchs     

B. Scheffer  J. Blankenburg 《植物养料与土壤学杂志》1983,146(3):275-284

Leaching of phosphorus out of fen soils - Results from pot trials without growing plants In contrast to acid bog peat soils, fen soils with high content of iron, calcium und partially lime may fix phosphates in the same way as mineral soils. In model experiments without growing plants the quantity of leached phosphorus is determined. 0,4–0,5 kg P/ha are leached out of a slightly acid fen soil (pH 5,5) with 550 mm percolated water. The phosphate fertilizers (300 kg P/ha) Tripelphosphat, Novaphos, Hyperphos and Thomasphosphat have no influence on the amount of leached phosphorus. The phosphate is fixed in the depth of 0–10 cm, into which the fertilizers were mixed. However, from a very strongly acid fen soil (pH 3,0; limed in 0–10 cm to pH 4,5) with 1000 mm percolated water 25,8 kg P/ha are leached. The fertilization with Tripelphosphat and Novaphos increases the amount of leached phosphorus whereas the water insoluble phosphate fertilizers (Thomasphosphat and Hyperphos) have no influence. In a fen soil with high content of iron water soluble phosphate will be sorbed and fixed very rapidly, therefore only low parts of the water soluble phosphate fertilizers can be extracted with lactate solution (DL), in comparison to the water insoluble phosphates.  相似文献   

Ecology. Globalization, roving bandits, and marine resources     

Berkes F  Hughes TP  Steneck RS  Wilson JA  Bellwood DR  Crona B  Folke C  Gunderson LH  Leslie HM  Norberg J  Nyström M  Olsson P  Osterblom H  Scheffer M  Worm B 《Science (New York, N.Y.)》2006,311(5767):1557-1558

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The identification and interpretation of differences in the transcriptomes of organically and conventionally grown potato tubers     

van Dijk JP  Cankar K  Hendriksen PJ  Beenen HG  Zhu M  Scheffer S  Shepherd LV  Stewart D  Davies HV  Leifert C  Wilkockson SJ  Gruden K  Kok EJ 《Journal of agricultural and food chemistry》2012,60(9):2090-2101

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Chemisch-mineralogische und mikromorphologische untersuchung einer eutrophen (Ramann-) braunerde des Budapester Hügellandes     

F. Scheffer  H. Gebhardt 《Geoderma》1977,17(2):145-163

In spite of the fact that Ramann's concept of Braunerde was extensively used throughout the world, some pedogenic processes and soil properties which are important for the formation and existence of Brown Forest Soils (eutrophic brown earths) are still not well known. Hence, a soil was investigated which was classified as a “Braunerde” by Ramann in 1909. The main question was, whether there might be soil constituents such as inorganic amorphous substances (allophanes) which are able to stabilize the brown-earth fabric, or to inhibit clay migration. From chemical data as well as from the magnitude of the pH-dependent CEC, it was deduced that there are no appreciable amounts of allophanes within the soil. The fabric, however, seems to be stabilized by colloid-chemical flocculation of the clay particles caused by large amounts of carbonates and silicates deposited with the parent material (loess). The decalcified solum is still rich in silicates, especially sand and coarse-silt-sized micas and feldspars (60–200 and 20–60 μm fractions, respectively). Since - in comparison - loesses and loess-derived soils of the Central German mountain region contain less silicates, mainly in fine and medium silt fractions (2–6 and 6–20 μm diameter, respectively), the coarser-grained silicates were assumed to be important for maintaining the Ca²⁺ and Mg²⁺ saturation of the soil by continuous weathering and thus stabilizing the brown-earth fabric.Although the soil is saturated predominantly with Ca²⁺ and Mg²⁺ ions, clay migration proceeds within the upper horizons. This was shown by calculation of the amounts of clay formed by breakdown of micas originally present in the parent material (“clay formation balance”), as well as by micromorphological studies. Furthermore, micromorphological studies and x-ray diffraction data gave some evidence for the migration of preferably finest grained montmorillonitic clays (smectites) penetrated by organic substances (humus). This kind of “selective clay migration” was assumed to be caused by high Ca²⁺ (or Mg²⁺) concentrations in soil solution required for flocculation of humus-penetrated (humus-coated) smectites. From the occurrence of these “humus-smectites” the possibility was assumed that the soil studied has been developed from a former Chernozem type.Quantitatively, clay migration does not reach the amounts of clay formation (breakdown of micas) accompanied by precipitation of iron oxides on mineral surfaces (“Verbraunung”). Thus, the soil profile visually and macromorphologically clearly exhibits the features of brown earths. On the other hand, however, some clay migration was observed. Hence, the soil was classified as a “brown earth with some clay migration” (“schwach durchschlämmte Braunerde”).Judging from the results of the “clay formation balance” an appreciable pedogenic (autigenic) clay formation from weathering products of feldspars was excluded for the soil studied.  相似文献   

Inhibition of potato sprout growth by carvone enantiomers and their bioconversion in sprouts     

K. Oosterhaven  K. J. Hartmans  J. J. C. Scheffer 《Potato Research》1995,38(2):219-230

Summary The monoterpenes (R)-(−)-carvone and (S)-(+)-carvone inhibited sprout growth in a model system consisting of sprouts growing from potato eye pieces. The sprout tissue was not necrotic after carvone treatment and the inhibition was reversible, since after treatment the sprouts showed regrowth either by continued top growth or by branching. However, the effect of both isomers on sprout growth differed, and (S)-(+)-carvone inhibited the elongation of the sprouts sooner than did (R)-(−)-carvone. This might be explained by a faster uptake of the former, since the concentration of (S)-(+)-carvone and its derivatives was twice as high during the first 4 days compared with (R)-(−)-carvone-treated sprouts. The sprouts were able to reduce (R)-(−)-carvone mainly into neodihydrocarveol, and (S)-(+)-carvone into neoisodihydrocarveol; in addition hydroxylated compounds were also detected. To whom correspondence should be addressed  相似文献   

Control of Dutch elm disease by the sterol biosynthesis inhibitors fenpropimorph and fenpropidin     

R. J. Scheffer  A. C. Brakenhoff  A. Kerkenaar  D. M. Elgersma 《European journal of plant pathology / European Foundation for Plant Pathology》1988,94(3):161-173

Sterol biosynthesis inhibitors that inhibit the yeast-hyphae conversion inOphiostoma ulmi suppressed Dutch elm disease development in two elm clones. After curative treatment with fenpropimorph-sulphate of 27 Vegeta elms which had previously been inoculated withO. ulmi, 25 trees did not show disease symptoms by the end of the second season. All 41 control trees, inoculated withO. ulmi only, were clearly diseased. In an experiment with Commelin elms three fenpropimorph salts and thiabendazole were compared. Injection of the trees three weeks after inoculation withO. ulmi gave by the end of the second season no symptoms of Dutch elm disease in any of the trees injected with fenpropimorph-phosphate or thiabendazole, and in most trees injected with fenpropimorph-acetate or-sulphate. Similar treatments with the free base of fenpropimorph and fenpropidin-sulphate were less effective due to insufficient uptake of the fenpropimorph emulsion and phytotoxicity of fenpropidin-sulphate, respectively. Injection of fenpropimorph-sulphate or thiabendazole six weeks after inoculation withO. ulmi did not result in significant differences from the control group inoculated withO. ulmi only.Fenpropimorph-phosphate and-sulphate completely suppressed Dutch elm disease upon injection of only 7.5 or 10 g per tree (average tree diameter 28 cm). Residue analyses showed only a slow decrease in concentration of the fungicide over two growing seasons and an apparent transport into the new annual ring, other prerequisites for a possible future use for control of Dutch elm disease.Samenvatting De iepeziekte kan onderdrukt worden door sterolbiosyntheseremmers die de overgang vanOphiostoma ulmi van de gistvorm in de hyfevorm remmen. Aan het eind van het tweede seizoen na een curatieve behandeling van 27 Vegeta iepen met fenpropimorfsulfaat bleken 25 bomen geen symptomen van iepeziekte te vertonen. Alle controlebomen, die alleen metO. ulmi geïnoculeerd waren, waren duidelijk ziek. In een proef met Commelin iepen werden drie fenpropimorfzouten en thiabendazool vergeleken. De zouten werden drie weken na de inoculatie metO. ulmi geïnjecteerd. Aan het eind van het tweede seizoen vertoonden geen van de bomen die met fenpropimorffosfaat of thiabendazool geïnjecteerd waren en slechts enkele bomen die met fenpropimorfacetaat of-sulfaat geïnjecteerd waren iepeziektesymptomen. Behandelingen met fenpropimorf (vrije base) en fenpropidinsulfaat werkten minder goed door de slechte opname van de fenpropimorfemulsie en de fytotoxiciteit van fenpropidin. Injectie met fenpropimorfsulfaat of thiabendazool zes weken na inoculatie leidde niet tot significante verschillen met de controlegroep die alleen metO. ulmi geïnoculeerd was.Een dosis fenpropimorffosfaat of-sulfaat van 7.5 of 10 g per boom met een gemiddelde boomdiameter van 26 cm bleek de iepeziekte volledig te kunnen onderdrukken. Uit residue-onderzoek bleek dat de concentratie van het fungicide gedurende de twee groeiseizoenen slechts langzaam afnam en dat het middel naar de nieuwe jaarring werd getransporteerd, twee voorwaarden voor een toepassing op praktijkschaal van fenpropimorf voor de bestrijding van de iepeziekte.  相似文献   

Phytotoxins and plant pathogenesis     

R. J. Scheffer 《European journal of plant pathology / European Foundation for Plant Pathology》1990,96(4):226-226

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