干气密封失效原因分析与有效性措施

针对西气东输站场内压缩机组干气密封频繁失效并造成高额维修更换费用的问题，从干气密封的基本结构和工作原理出发，分析了西气东输管道干气密封实际应用效果，重点剖析了部分压缩机组站场干气密封失效的原因，根据实际生产运行中得出的结论，在收集和分析西气东输各站影响干气密封事件的同时，深入分析了导致干气密封失效的一系列因素，并从压缩机的设计、干气密封系统设计、阻挡密封、干气密封的运输和储藏、安装和拆卸、运行和维护6个方面提出了提高干气密封有效性的针对性措施，以期对压缩机站场干气密封的使用及维护提供指导。（图6，参6）     

棉花钾素吸收利用效率与产量的关系

为明确钾素吸收利用效率对产量及构成的影响,2007~2008年在扬州大学以不同的钾吸收利用效率品种为材料,进行施钾肥与不施钾肥处理试验,以通径和相关分析探讨了钾素吸收利用与棉花产量的关系。结果表明,钾肥利用率高的品种产量不高,钾肥农学利用率、钾素生理利用率和籽棉生产效率高的品种产量高;钾素生理利用率对铃数和产量的直接贡献最大,钾肥农学利用率通过生理利用率对产量和铃数的间接贡献最大;钾肥利用率对铃质量的贡献最大。钾肥利用率和农学利用率提高有利于中下部和内围产量及铃数提高,钾肥生理利用率和籽棉生产效率提高则有利于上部产量和铃数提高。在钾素利用上提高生理利用效率和籽棉生产效率则是提高整株产量实现高产的重要途径。     

水分胁迫对桔梗生长发育的影响

为了研究了不同水分胁迫对桔梗生长发育以及有效成分积累的影响。通过对桔梗采用室外盆栽控水,试验设土壤相对含水量40%,60%,80%三个梯度,测定不同生长发育阶段地上、地下部分的质量以及有效成分含量。结果表明随着水分胁迫程度的加强,地上、地下部分的生长均受到抑制,但对地上部分的抑制更明显,而对有效成分的积累有显著的促进作用。因此水分条件是影响桔梗生长发育的重要因子之一;当土壤相对含水量在60%的条件下,桔梗的产量和质量兼顾。     

覆盖方式对上部烟叶质量的影响

研究不同覆盖方式对上部烟叶质量的影响。结果表明,揭膜盖草加喷施硅肥可提高上部叶PSⅡ的最大光化学量子效率(F_v/F_m)、实际光化学效率(ΦPSⅡ)和光化学猝灭系数(q P)等荧光参数;与揭膜不盖草(CK)处理比较,揭膜盖草+钾肥和揭膜盖草+硅肥处理的烟株叶重和总干重显著增加;揭膜盖草+硅肥处理的上部烟叶物理性状最好、化学成分最协调。     

氮磷钾用量对烤烟‘湘烟5号’产质量的影响

探讨不同氮磷钾施用量对烤烟‘湘烟5号’产量和品质的影响,为永州烟区‘湘烟5号’的进一步推广示范提供科学依据。试验设氮、磷、钾各3个处理水平,采用正交L₉(3 ⁴)设计,田间调查各处理烟叶的农艺性状、主要经济性状和质量。结果表明,各处理的产量、产值、均价、烟叶等级比例均有差异,其中以处理N135P108K378的经济性状较好,烤后烟叶的糖碱比、氮碱比、钾氯比均较适宜,烟叶内在化学成分较协调,经济效益好。永州烟区土壤中等肥力下‘湘烟5号’的氮磷钾最佳施用量为N:P:K=135:108:378。     

日喀则地区马铃薯钾肥效应及栽培模式研究

通过对5个不同处理的钾肥施肥量和3种不同栽培模式的研究,探讨在高海拔的干旱半干旱地区增施钾肥的必要性和适合马铃薯种植的最佳栽培模式。研究结果表明,增施钾肥后能够促进马铃薯的生长发育,产量和商品薯率都有所增加,说明在高海拔的干旱半干旱地区增施钾肥是有必要的。同时通过不同栽培模式的研究说明,起垄覆膜处理增温效果明显,有利于干旱半干旱地区马铃薯提前出苗,促进生长,缩短生育期,提高产量和商品率。     

Biological Control of Common Bunt (Tilletia tritici)

Summary

Common bunt (Tilletia tritici syn. T. caries) is a significant seed-borne plant disease in organic agriculture. General measures in ecological crop protection like crop rotation and manuring have in practice failed to control this disease, and direct seed treatment may be necessary to ensure yield and food quality. The present study indicates that biological control can be successfully used without negative effects on seed germination and vigor. A combination of biocontrol agents and milk powder improves the efficacy of biocontrol. Application of compost to the soil increases the frequency of this disease. The potential role of biocontrol within the principles of ecological disease management is discussed.     

高钾肥力土壤增施钾肥对马铃薯的生物效应

为了优化马铃薯生产过程中肥料养分管理和高效利用，于2011年在甘肃省定西市选择高钾肥力土壤布置大田试验，在等氮磷用量基础上，研究了施钾水平（0，120，240，360，480 K₂O kg·hm^-2）对马铃薯产量和品质及经济效益的影响。结果表明，马铃薯商品率、产量和产值随施钾水平的提高而呈先增高后下降的趋势，商品率、产量以K120和K240较高，但纯收入以K120最高；马铃薯块茎淀粉、总糖、还原糖、Vc、蛋白质和干物质含量随施钾水平的提高而呈先增高后下降的趋势，淀粉和总糖含量以K240最高，而还原糖、Vc、蛋白质和干物质含量以K120最高，说明在高钾肥力土壤上适量增施钾肥可以提高马铃薯的产量和改善其品质。本试验条件下，马铃薯最高产量施钾量与经济最佳施钾量分别为162.06 kg·hm^-2和126.44 kg·hm^-2。     

Effect of nitrification inhibitor on nutrient composition of winter wheat forage 1

Winter wheat (Triticum aestivum L.) is an important source of forage for cattle in the southern Plains. While high in quality, wheat pasture is prone to cause thousands of cattle deaths annually from nitrate poisoning, bloat, and wheat pasture poisoning, a syndrome of unknown cause. A large portion of the stocker cattle deaths on nitrogen fertilized pastures occur from unknown causes that appear to be related to forage composition. The objectives of this study were to determine seasonal trends in nutrient composition and to determine the effect of nitrapyrin, a nitrification inhibitor, on the change in nutrient composition of wheat forage over winter. The wheat was planted the last week of August on a Pullman clay loam soil (fine, mixed, thermic Torrertic Paleustol). Clip samples were collected periodically and analyzed for nutrient composition. Nitrogen, phosphorus, and potassium concentrations of the wheat forage varied during the season. Levels tended to be highest with the onset of growth and to decline as growth was decreased by cold weather. Nitrapyrin did not affect the concentration of any of the nutrients examined in the wheat forage. Concentration of nutrients, other than potassium, tended to be highly correlated with each other in both years of the study.     

Climate‐driven population dynamics of a North American freshwater fish,Ictalurus furcatus: inference from the mitochondrial control region sequence data

Abstract – Using the Bayesian coalescent methodology and mitochondrial control region sequence data, the present study reconstructs the dynamics of effective population size of a temperature‐driven seasonal migratory North American freshwater fish, Ictalurus furcatus, during the last glacial cycle. The trend in effective population size is directly associated with the trend in surface air temperature; it is inversely associated with the accumulation of ice sheets in North America during the contemporary period. The long‐term decrease in effective population size during the cold period followed by rebound during the warmer period could be explained by this species’ preference for relatively warmer temperatures for its optimal growth and survival.