Relationship between soil organic matter and micropores in a long-term experiment at Ultuna,Sweden

Our study showed that long‒term addition of organic matter to a fine textured soil (36.5% clay, 41% silt, 22.5% sand) resulted in an increase of both macro‒ and microporosity in the top soil layer. In terms of changes of the absolute pore volume, macropores were of main importance. However, in relative terms, the increase of microporosity was comparable to that of macroporosity (75% and 90%). Changes in porosity upon different organic matter levels had a marginal effect on the water storage capacity. Micropores with diameters in the range of 1—30 μm were highly significantly correlated to soil organic matter characteristics showing that there is a non‒uniform distribution in relation to pores. Mechanisms leading to disproportionally high concentrations of soil organic matter in relation to micropores are discussed.     

Structure-specific detection of plant cuticle bound residues of chlorothalonil by ELISA

Monoclonal antibodies (mAb) against the main photo-addition products of chlorothalonil with olefinic compounds of plant cuticles were produced. An indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed for the detection of free and bound chlorothalonil and its derivatives. For the characterization of the binding properties of the mAb, derivatives of chlorothalonil (simulating structures of cuticle bound residues) were synthesized. The cross-reactivities of these products were determined by ELISA. The test system was employed to detect bound residues of chlorothalonil in enzymatically isolated tomato cuticles, which had been spiked with methanolic solutions of the compound, irradiated by simulated sunlight and extracted. The use of isolated cuticles allows work to be carried out with authentic material without disturbance by metabolic processes. © 1999 Society of Chemical Industry     

Stable isotopes infer the value of Australia’s coastal vegetated ecosystems from fisheries

Wild capture fisheries provide substantial input to the global economy through employment and revenue. The coastal zone is especially productive, accounting for just 7% of the total area of the ocean, but supporting an estimated 50% of the world's fisheries. Vegetated coastal ecosystems—seagrass meadows, tidal marshes and mangrove forests—are widely cited as providing nutritional input that underpin coastal fisheries production; however, quantitative evidence of this relationship is scarce. Using Australia as a case study, we synthesized fisheries stable isotope data to estimate nutritional input derived from coastal vegetated ecosystems and combined these “proportional contribution” estimates with total annual catch data from commercial fisheries to determine species‐specific dollar values for coastal vegetated ecosystems. Based on the data from 96 commercially important fish species across Australian states (total landings 14 × 10⁶ tonnes pa), we provide a conservative estimate that Australia's coastal vegetated ecosystems contribute at least 78 million AUD per year to the fisheries economy. Two thirds of this contribution came from tidal marshes and seagrasses that were both equally valued at 31.5 million AUD per year (39.4%) followed by mangroves at 14.9 million AUD per year (18.6%). The highest dollar values of coastal ecosystems originated from eastern king prawn (Melicertus plebejus) and giant mud crab (Scylla serrata). This study demonstrates the substantial economic value supported by Australia's coastal vegetated ecosystems through commercial fisheries harvest. These estimates create further impetus to conserve and restore coastal wetlands and maintain their support of coastal fisheries into the future.     

Novel lysimeter techniques — a basis for the improved investigation of water,gas, and solute transport in soils

For many years lysimeters have been proven to be effective tools in assessing and predicting the effects of current land use and future land use changes in catchment areas on both water and solute balances. Although due to the diverse aspects of mass transport modelling, many different types of lysimeters exist, water and solute balances are by no means fully understood, especially in post‐mining areas. To tackle this problem, a new piece of equipment has been developed which enables the actual weight of a lysimeter to be precisely measured. The newly designed device, which has been used for one of the experiments described in this paper, permits the weighing of for example a 2 m³ lysimeter vessel with an accuracy down to 30 g. The second newly developed appliance presented here is the GAMS (Gas‐Migration‐Simulator). Basically comparable to a lysimeter, the difference is that the GAMS allows the detailed investigation of soil‐gas migration processes and their dependence on parameters like the diffusion coefficient and the gas permeability of the soil, alterations of the groundwater level and on various external influences such as changes of the actual meteorological conditions. These two newly developed techniques are described in this paper, and their respective suitability is demonstrated on the basis of data sets recorded during initial experiments.     

Molecular mechanisms of salinity tolerance in rice

Salinity is one of the major abiotic stresses which impose constraints to plant growth and production. Rice (Oryza sativa L.) is one of the most important stapl...     

甘蓝型油菜-萝卜附加系中萝卜染色体的（dp）RAPD标记

在已掌握甘蓝型油菜-萝卜附加系染色体构成,并构建萝卜分子连锁图谱的基础上,以甘蓝型油菜?萝卜附加系为材料,利用(dp)RAPD分子标记技术,筛选附加系中外源萝卜9条染色体(A～I)的分子标记,为进一步研究萝卜染色体与连锁群对应关系奠定基础。试验筛选了576个随机引物(组合),有413个能从附加系中扩增出萝卜染色体的(dp)RAPD标记,平均有效引物(组合)占71·7%,其中RAPD反应有效引物率67·7%,dpRAPD反应有效引物率73·2%。试验共得到899个萝卜染色体(dp)RAPD标记,包括354个RAPD标记和545个dpRAPD标记,覆盖萝卜整个基因组的全部9条染色体,不同染色体的标记数目变化范围在41～160,其中最多的是染色体C,最少的是染色体I。     

Increasing control reliability of <Emphasis Type="Italic">Orobanche cumana </Emphasis>through integration of a biocontrol agent with a resistance-inducing chemical

Fusarium oxysporum Schlecht. f.sp. orthoceras (Appel & Wollenw.) Bilai is a potential biocontrol agent against the root-parasitic weed Orobanche cumana. In pot experiments with different sunflower cultivars, the application of F. oxysporum was combined with a treatment of BTH (Benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester), a product known to induce resistance against O. cumana in sunflower. The combined treatments resulted in highly reliable control and sometimes in increased control level compared to the Fusarium treatment alone. In laboratory experiments, no enhancing effect of BTH on virulence and growth of the fungus was observed. Future experiments should further investigate the basic mechanisms of the effect achieved by combining the two control strategies as well as the transfer of this innovative control approach into field experiments.     

萝卜-甘蓝型油菜中萝卜基因组的RAPD与dpRAPD分析效率研究

应用RAPD与dpRAPD方法鉴定萝卜-甘蓝型油莱中萝卜基因组,筛选了140条随机引物。结果表明,平均每条引物(组合)能产生的萝b基因组特异标记数dpRAPD高于RAPD,分别为1．69和1．33;在dpRAPD扩增产物中有77．6％谱带清晰易辨,略高于RAPD(75．4％)。两者所检测到的萝卜基因组标记大部分为各自特异的扩增产物。由于结合了荧光标记引物,dpRAPD反应产物可在Genetic Analyzer上分离检测,因此能检测到100bp以下的小片段DNA。     

Impact of horse grazing and feeding on phosphorus concentrations in soil and drainage water

The number of horses in Sweden has increased, from 77 300 in 1970 to 283 000 in 2003 (ca. 250%). These horses are kept on 300 000 ha, which represents 10% of total agricultural land in Sweden. Maximum recommended livestock density in Sweden is 2.5 units/ha for grazed pasture, but no limits have yet been set for outdoor keeping and feeding areas (paddocks) for horses. This study characterized the potential risk of phosphorus (P) losses from a horse paddock established on a heavy clay soil with a stocking rate of 3.75 livestock units/ha compared with nearby arable land. The horse paddock received 15 kg P/ha/yr and 75 kg N/ha/yr through horse excreta, while annual input of P and N to the adjacent arable land was 13 and 112 kg/ha, respectively. There was no significant difference in water‐soluble P (WSP) in fresh and dried soil samples between the horse paddock (mean values: 0.62 and 0.43 mg/100 g soil; n = 15) and the arable field (mean values: 0.52 and 0.37 mg/100 g soil; n = 5). In contrast, phosphorus extractable in ammonium acetate lactate (extractable P) in the topsoil of the horse paddock (mean: 15 mg/100 g soil) was significantly higher (P = 0.03; n = 15) than in the arable land, whereas total P extracted with nitric acid (total P) showed no statistically significant differences. Furthermore, there was no significant difference in lactate‐extractable iron and aluminium (extractable Fe and Al), organic carbon (C), total nitrogen (N) or phosphorus sorption index between the two parcels of land. However, the degree of P saturation in soil was significantly higher (P = 0.02; n = 15) in the horse paddock. Extractable Al and Fe were highly correlated to extractable P (P < 0.001; n = 69), the correlation being negative for Al. No relationship was found with calcium, but soil C content was found to be correlated with extractable P (P < 0.001; n = 69). Over the past 8 yr, high P concentrations (up to 1.5 mg/L), mainly in dissolved reactive form, have been recorded in drainage water from the grazed catchment. We concluded that horse grazing at high stocking rates (>2.5 livestock units/ha) may pose a risk of high P losses to nearby water bodies.