The effect of source of nitrogen on the dry matter yield,nitrogen and nitrate‐N content of Lolium multiflorum

Three sources of N fertilizer (urea, limestone ammonium nitrate (LAN) and ammonium sulphate) showed no consistent significant trends in terms of the dry matter yield and nitrogen or nitrate‐N content of midmar ryegrass. Ammonium sulphate was found to acidify the soil markedly, relative to urea, with LAN showing the least acidifying effect.     

Effects of fertiliser applications on survival and recruitment of the apple snail,Pomacea canaliculata (Lamarck)

Since its introduction to Asia in the 1980s, the golden apple snail, Pomacea canaliculata (Lamarck), has represented a major constraint to the profitability of rice (Oryza sativa L.) farming by damaging rice seedlings during crop establishment. This study describes a series of experiments designed to determine the effects of nitrogenous fertilisers on snail fitness. We examined the possibility of a two-phase model of snail response to nitrogen, whereby fertilisers initially increase snail mortality through toxicity, but once assimilated into the rice ecosystem, eventually favour snail reproduction and survival. In experimental arenas, fertiliser had lethal effects: Complete fertiliser (14:14:14), urea, ammonium sulphate and organic fertilisers were associated with snail mortality, generally affecting adult snails more than juvenile snails, and with greater effects when applied to saturated soil that was subsequently flooded (as opposed to direct application to flooded soil). Snail mortality was found to decline considerably when snails were added to arenas one day after fertiliser application – this occurred in arenas with soil and water, but not in arenas with water only, suggesting that soil can reduce the toxic effects of fertilisers. In a field experiment, snail numbers declined in both fertilised and non-fertilised plots at the time of crop establishment. Numbers increased in all plots after rice tillering, with significantly more recruitment in plots with high nitrogen. Although the responses were generally weak in the field experiment, they did support the two-phase model. The consequences of fertiliser applications for snail management and ecosystem health are discussed.     

中竹集团竹浆原料林基地建设现状

中竹纸业集团是目前中国最大的漂白硫酸盐竹浆生产企业，从事竹资源综合利用和深加工。公司采用建设竹浆原料林基地的方法促进竹浆产业的发展，使中国的竹资源得到有效的利用。本文就竹林基地建设的发展，公司＋农户的管理模式以及经营理念进行了阐述。     

Effects of a constant rate infusion of magnesium sulphate in healthy dogs anaesthetized with isoflurane and undergoing ovariohysterectomy

ObjectiveTo determine the effects of intravenous (IV) magnesium sulphate (MgSO₄) as a bolus followed by a constant rate infusion (CRI) on anaesthetic requirements, neuroendocrine stress response to surgery, haemostasis and postoperative analgesia in healthy dogs undergoing ovariohysterectomy.Study designBlinded randomized clinical trial.AnimalsSixteen female dogs.MethodsAfter intramuscular premedication with acepromazine (0.05 mg kg^?1) and morphine (0.3 mg kg^?1), anaesthesia was induced with diazepam (0.2 mg kg^?1) and propofol (2 mg kg^?1) intravenously and maintained with isoflurane in oxygen in all dogs. Dogs were randomly assigned to two groups, M and C. Group M received MgSO₄ (50 mg kg^?1 over 15 minutes, followed by a 15 mg kg^?1 hour^?1 CRI). Group C received an equivalent bolus and CRI of lactated Ringer's solution. In addition, all dogs received lactated Ringer's solution (10 mL kg^?1 over 15 minutes followed by 10 mL kg^?1 hour^?1). End-tidal isoflurane and carbon dioxide tensions, cardio-respiratory variables, arterial blood gases, electrolytes, ACTH and cortisol concentrations were measured at different time points. Thromboelastography (TEG) was performed pre- and post-anaesthesia. Postoperative pain was evaluated using the short form of the Glasgow Composite Pain Scale. Data were analysed with repeated measures anova and Mann–Whitney U tests (p< 0.05).ResultsNo statistically significant differences between groups were found in any of the measured variables. However, the alpha angle and maximal amplitude recorded by TEG in group M were significantly increased post-anaesthesia, but remained within the reference interval. One dog in Group M and two in Group C received rescue analgesia during recovery.Conclusions and clinical relevanceAs used in this study, MgSO₄ failed to decrease isoflurane requirements, postoperative pain and stress hormone concentrations; however, it did not produce any cardio-respiratory or major haemostatic side effects. Administration of intravenous MgSO₄ together with an opioid during ovariohysterectomy in dogs does not seem to provide any clinical advantage.     

高效液相色谱法测定硫酸安普霉素有关物质

建立了硫酸安普霉素有关物质测定的高效液相色谱法。硫酸安普霉素有关物质经磺酸基键合硅胶柱分离,茚三酮溶液衍生后,568 nm处测定。结果显示,测得的硫酸安普毒素8种有关物质得到良好分离。对硫酸安普霉素及其制剂测定结果表明,该方法适合硫酸安普霉素有关物质的测定。     

锰源和锰水平对南美白对虾生长性能和组织锰含量的影响

南美白对虾配合饲料中添加10、20、30mg/kg的硫酸锰和甘氨酸锰。饲养8周,于试验第4、8周末称重,并在第8周末测定对虾肝胰脏和肌肉中的锰含量。试验结果表明:甘氨酸锰各水平组和20、30mg/kg硫酸锰组显著提高了对虾第4周末的体重,锰源和锰水平对第8周末的体重无显著影响。肌肉中的锰含量不受锰源和锰添加量的影响,但肝胰脏中的锰含量表现为随锰添加量的增加而呈升高的趋势。综合生长和锰含量指标,饲料中添加10mg/kg的甘氨酸锰或30mg/kg硫酸锰为好。     

A review of the effects of humidity, humectants, and surfactant composition on the absorption and efficacy of highly water-soluble herbicides

It is well known that environmental conditions have an important influence on herbicide efficacy. In particular, the effect of humidity on herbicide uptake has been attributed to changes in cuticle hydration and droplet drying. As early as the 1950s, it was hypothesized that humectants such as glycerol would enhance herbicide uptake by not letting droplets dry, thus maintaining the herbicide in solution, and hence making it available for uptake. Shortly thereafter, evidence was found to support this hypothesis and humectants were used successfully in warm, dry areas to increase herbicide efficacy. However, by the mid-1980s, there was little use of humectants as research on humectants gave way to investigations on the effect of ethylene oxide (EO) content on surfactant performance to improve herbicide uptake and efficacy. While ethoxylated surfactants effectively increase the uptake of both lipophilic and hydrophilic herbicides, the suggestion that long EO chains have humectant properties is misleading, since the studies that led to this suggestion were performed at high humidity, which would prevent rapid droplet drying. Furthermore, current evidence suggests that highly water-soluble, ionic herbicides may be more sensitive to low humidity and rapid drop drying than lipophilic herbicides. Therefore, an overview is presented on the interaction of water-soluble herbicides with surfactants, the cuticle, and humidity, with particular emphasis on the impact of low humidity and humectants on herbicide uptake. It was found that when one focuses on research performed at low humidity the importance of humectants emerges, which is not in keeping with what is now commonly accepted.     

高硫酸盐有机废水厌氧处理技术的进展

本文通过硫酸盐还原菌和产甲烷菌的竞争、硫化物对产甲烷菌的毒害二方面,论述了在高硫酸盐有机废水厌氧处理过程中,硫酸盐还原作用对产甲烷菌活性的抑制机理,同时,介绍了当前高硫酸盐有机废水的厌氧处理工艺     

Effects of inorganic and organic dietary copper supplementation on growth performance and tissue composition for juvenile red drum (Sciaenops ocellatus L.)

A feeding trial was conducted to evaluate the dietary copper requirement of red drum (Sciaenops ocellatus) and compare the bioavailability of copper sulphate (CuSO₄) and copper‐ethanolamine. A basal diet was formulated using semi‐purified ingredients and analysed to contain 3 mg Cu/kg. Both copper sources were supplemented to the basal diet at either 5, 10 or 20 mg Cu/kg of dry diet. No significant differences were observed in growth performance of fish fed the various diets. However, red drum fed all copper‐supplemented diets retained more copper in liver and whole‐body tissues compared to fish fed the basal diet. Within both inorganic and organic copper treatments, the highest tissue copper concentrations were observed in fish fed diets supplemented with 10 mg Cu/kg. No significant differences were detected in net copper retention regardless of the nature of the copper source; hence, the bioavailability of copper sulphate and copper‐ethanolamine complex was not different in the diets for juvenile red drum. Furthermore, the minimum copper requirement for growth performance of juvenile red drum appeared to be satisfied when fish were fed the basal diet containing 3 mg Cu/kg diet, and no detrimental effects were observed in red drum fed diets supplemented with 20 mg Cu/kg.     

Susceptibility of channel catfish, Ictalurus punctatus (Rafinesque), to Edwardsiella ictaluri challenge following copper sulphate exposure

Channel catfish, Ictalurus punctatus (Rafinesque), with or without a preliminary 24 h exposure to 2 mg copper sulphate L(-1), were challenged with 7.5 x 10(6) colony forming units L(-1) of Edwardsiella ictaluri to determine the effect of copper sulphate on disease resistance. Catfish previously exposed to copper sulphate were significantly more resistant to the bacterial challenge than those not exposed. Catfish not exposed to copper sulphate suffered 35.5% mortality while catfish exposed to copper sulphate experienced 14.1% mortality. Copper concentrations were the same in tank waters of both exposed and control fish at the time of challenge, eliminating the possibility that copper in the water may have been toxic to bacteria. Copper concentrations in freeze dried and ground tissues of unexposed, exposed, and purged channel catfish were highest in fish before copper sulphate exposures suggesting that elevated tissue levels of copper were not responsible for the increased resistance to bacterial challenge. Competition for sites of bacterial attachment to gill or epithelial cells may account for the reduction in mortality; although this is not supported by the low copper content of fish tissue after copper exposure.