不同干燥方法对鸭茅营养成分及其损失的影响

研究干燥方法对鸭茅(不同生育阶段)营养成分及其损失量的影响。结果表明:(1)随着生育期的推进,粗蛋白质和粗灰分含量逐渐下降,中性洗涤纤维和酸性洗涤纤维含量逐渐增加,而水溶性碳水化合物含量开始不断增加,开花期最高,结实期又迅速减少;干燥方法对水溶性碳水化合物含量的影响极其显著(P<0.01),其含量的顺序为:烘干>晒后烘干>晒干>阴干。(2)干燥方法与营养物质的损失量间差异显著(P<0.05),其损失量的顺序为晒后烘干>晒干>阴干。不同干燥方法的水溶性碳水化合物损失量与干物质、粗灰分、无氮浸出物损失量之间呈显著相关,相关系数分别为0.8798、0.6404和0.6568。     

磷对奶牛红细胞膜脂质的影响

对１５例临床上有明显低磷血症的奶牛血清磷、红细胞膜脂质成分进行了测定。结果表明，低磷血症奶牛血清磷、红细胞膜磷脂明显降低；红细胞膜胆固醇及膜胆固醇／磷脂摩尔比值（ｎｃｈ／ｎｐｌ）明显升高，与健康对照组牛相比差异极显著（Ｐ＜０．０１）；直线相关分析表明，血清磷与红细胞膜磷脂之间呈极显著正相关（ｒ＝０．９１７，ｙ＝１０．８５２ｘ＋３．１９６，Ｐ＜０．０１）；与红细胞膜胆固醇以及ｎｃｈ／ｎｐｌ之间分别呈显著负相关（ｒ＝－０．９４０，ｙ＝２．８５０ｘ－１．０７２，Ｐ＜０．０１；ｒ＝－０．９２０，ｙ＝１．９６８ｘ－１．４０１，Ｐ＜０．０１）。此外，红细胞膜微粘度与膜磷脂之间呈显著负相关（ｒ＝－０．９５４，ｙ＝１９．１２２ｘ－４．３８４，Ｐ＜０．０１），而与膜胆固醇以及ｎｃｈ／ｎｐｌ之间呈显著正相关（ｒ＝０．９８８，ｙ＝０．９２７ｘ＋０．９６４，Ｐ＜０．０１；ｒ＝０．９７８，ｙ＝－０．２９３ｘ＋１．１１３，Ｐ＜０．０１）。结果表明，磷是红细胞膜脂质成分改变的先决因素，而后者又是红细胞膜流动性及膜结构、功能发生变化并导致膜损伤的一个重要因素。     

Effects of high and low inspired fractions of oxygen on horse erythrocyte membrane properties, blood viscosity and muscle oxygenation during anaesthesia

ObjectivesTo evaluate whether a period of hyperoxia or after a period of hypoxia produced changes attributable to reactive oxygen species in anaesthetized horses.Study designProspective randomized experimental study.AnimalsSix healthy (ASA I) geldings, aged 4.5–9.5 years and weighing 510–640 kg^?1.MethodsAfter 30 minutes breathing air as carrier gas for isoflurane, horses were assigned randomly to breathe air as carrier gas (CG0.21) or oxygen as carrier gas (CG1.00) for a further 90 minutes. After an interval of 1 month each horse was re-anaesthetized with the other carrier gas for the 90 minute test period. Ventilation was controlled throughout anaesthesia. Arterial blood was sampled to measure gas tensions, lactate, cholesterol, vitamin E, 4-hydroxy-alkenals, 8-epi-PGF_2α, half haemolysis time, half erythrolysis time, and erythrocyte membrane fluidity. Muscle blood flow and oxygenation were evaluated by near infrared spectroscopy and coloured Doppler.ResultsAfter the first 30 minutes horses were hypoxemic. Subsequently the CG1.00 group became hyperoxaemic (PaO₂～240 mmHg) whereas the CG0.21 group remained hypoxaemic (PaO₂～60 mmHg) and had increased lactate concentration. No significant changes in vitamin E, 4-hydroxy-alkenals, or 8-epi-PGF_2α concentrations were detected. During the 90 minute test period the CG0.21 group had increased resistance to free-radical-mediated lysis in erythrocytes, whereas the CG1.00 group had slightly decreased resistance of whole blood to haemolysis. CG0.21 induced a progressive muscle deoxygenation whereas CG1.00 induced an increase in muscle oxygen saturation followed by progressive deoxygenation towards baseline.Conclusions and clinical relevanceDuring isoflurane anaesthesia in horses, the hyperoxia induced by changing from air to oxygen induced minimal damage from reactive oxygen species. Using air as the carrier gas decreased skeletal muscle oxygenation compared with using oxygen.     

Measurement of Concentration and Viability in Stallion Sperm

Sperm concentration and sperm membrane intactness (SMI) or viability are two measures of sperm quality that provide important but different information about a stallion's reproductive capability. Sperm concentration is a measure that, by itself, informs little about the reproductive status of either the stallion or the ejaculate. Nevertheless, it is part of the product, along with semen volume, that determines total sperm number. The correct calculation of total sperm number directly affects the number of mares a stallion can breed and therefore, fertility. If either sperm concentration or semen volume is incorrectly measured, both the number of mares that a stallion can breed and the fertility of those breedings are affected. Although considerable between-stallion variation exists, sperm concentration, semen volume and total sperm number tend to be seasonal and vary with ejaculation frequency.     

滇东地质高背景区土壤镉的伴矿景天修复及其对后茬水稻的影响

云南是我国典型的重金属元素地球化学高背景区,超积累植物能否有效修复镉（Cd）地质高背景土壤,从而实现农产品安全生产,尚鲜见报道。以云南石林、富源和罗平等三地的典型Cd地质高背景农田土壤为对象,开展温室盆栽试验,探究Cd、锌（Zn）超积累植物伴矿景天对土壤Cd的吸取修复效果,及对后茬水稻生长和Cd吸收的作用。结果表明,种植三季伴矿景天使三地土壤全量Cd分别下降24.8%、30.9%和58.8%;伴矿景天在富源玄武岩风化物母质发育的土壤上长势最好,与富源土壤肥力相对最高有关;伴矿景天在罗平石灰岩风化物发育的土壤上重金属吸取修复效果最佳,与罗平土壤呈中性、酸化作用更为明显有关,这些差异由土壤母质、养分与重金属有效性等综合影响所致。经伴矿景天吸取修复三季后,全生育期淹水种稻,其糙米和秸秆Cd浓度均大幅降低,可实现糙米Cd安全生产。未经植物吸取修复,旱作处理下水稻糙米Cd存在超标风险。植物吸取修复后种植水稻,再结合水分管理措施,可进一步降低稻米中Cd浓度,实现稻米安全生产,为Cd地质高背景区土壤的农作物安全生产提供理论依据和技术支撑。     

集雨灌溉工程研究综述

集雨灌溉工程是对降雨进行收集、汇流,存储和进行节水灌溉的微型水利工程,主要解决农业生产缺水性问题.通过国内外集雨灌溉利用的研究和实践,较详细地阐述了集雨灌溉工程的主要研究内容:集水工程集雨面防渗材料的研究、蓄水工程中蓄水设施的防渗,水分蒸发处理,喷灌、滴灌、渗灌等灌溉技术.文章分析了目前集雨灌溉工程研究存在的问题并提出了发展研究方向.     

基于FEM-SPH耦合的卷辊式耕层残膜回收部件结构优化与试验

针对棉田耕作层内残膜力学性能差及膜土分离困难,残膜拾净率低和回收的残膜含土量高等问题,该研究对卷辊式残膜回收部件进行优化。在分析起膜捡膜工作过程和建立卷辊弹齿与膜土团聚体之间动力学关系的基础上,采用有限元法(finite element method,FEM)和光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)耦合算法,建立卷辊弹齿-膜土团聚体接触计算模型,探究卷辊弹齿与膜土团聚体之间相互作用机理,分析卷辊弹齿接触膜土团聚体后残膜受力程度和土壤扰动程度的变化规律。以卷辊回转半径、弹齿直径、弹齿顶端折弯角为试验因素,以残膜平均峰值应力及土壤最大应变为指标开展仿真试验,分析各因素对指标的影响规律并对卷辊弹齿结构参数进行优化,获得卷辊弹齿最优结构参数为：卷辊回转半径100 mm、弹齿直径5 mm、弹齿顶端折弯角42°,此时残膜平均峰值应力为0.1201 MPa,土壤最大应变为3.7584。为了验证优化后卷辊弹齿的捡拾作业性能,以拾净率和含土率为试验指标进行田间试验,结果表明：机具拾净率为80.34%,含土率为37.13%,与初代研制的样机相比拾净率提升了8.74个百分点,含土率下降了12.18个百分点,机具作业性能明显提升且试验指标达到设计要求。本文建立的有限元模型可为残膜回收机关键部件的结构优化提供参考。     

Yield and growth characteristics for cotton under various irrigation regimes on sandy soil

Over-watering cotton wastes a valuable and scarce resource; it can also lead to rank growth, nutrient leaching, and contaminated groundwater. Since under-watering can decrease yields, the question becomes one of finding the optimum application regime. An irrigation experiment was set up to apply water at six different application rates, ranging from 33% to 144% of normal, with hopes of identifying the regime that produces maximum yield. Two cultivars, Acala Maxxa and Acala PhytoGen-72 (Gossypium hirsutum L.), were planted on sandy soil and irrigated daily with a highly efficient subsurface drip irrigation system for four seasons. The results showed that on the average there was no significant difference in the yield of the two cultivars and there was no significant difference in the yield for the three wettest treatments. The driest of the three wettest treatments, treatment 4, was a critical point on the water production function curve. It represented the least amount of water applied that still produced essentially maximum yield, and it had the highest water use efficiency. This critical level of water application during mid-season was found to be, on the average, 95% of Class A pan evaporation; it corresponded to a total seasonal application of 654 mm of water. Any application less than this critical level decreased yields. Reducing the water application by 5% below the critical level caused about a 4.6% reduction in yield. The critical level produced a soil moisture level that remained nearly constant throughout the season. The final plant height was closely related to the depth of water applied, with the wettest treatment producing plant heights of 2.0 m, and the driest treatment producing plant heights of 0.6 m. At the extremes of the water application rates there were some small differences in the early-season growth rate of the plants, but the main cause of differences in final plant height was the date of cutout (cessation of main stem node production). The length of season for the driest treatment was about 4 weeks shorter than for the wettest treatment on both cultivars. Results showed that deficit irrigation of cotton on sandy soil can greatly reduce yield, and the practice should probably be avoided.     

Effect of biochar on soil structure and storage of soil organic carbon and nitrogen in the aggregate fractions of an Albic soil

ABSTRACT

Field experiment was conducted to evaluate the effect of corn straw derived-biochar (700 °C) applied at 0 (control), 10 (B1), 20 (B2) and 30 t ha^?1 (B3) on water stable aggregate (WSA), mean weight diameter (MWD), total organic carbon (TOC) and total nitrogen (TN) in WSA fractions of Albic soil. Compared with control, WSA in > 2 mm fraction increased, by 40.8% and 51.5% (0–10 cm depth) in B1 and B3, respectively. B1, B2 and B3 (10–20 cm depth) increased by 55.2%, 69.6% and 62.4%, respectively. MWD increased by 34.4%, 21.6%, and 17.6% with B3 at 0–10 cm, 10–20 cm and 20–30 cm depths, respectively. TOC in the > 2 mm fraction increased by 28.6%, 22.1%, and 23.2% (0–10 cm depth) in B1, B2, and B3, respectively, TN in 2–0.5 mm fractions increased by 32.4%, 23.4% and 33.6% (0–10 cm depth); and in the 0.25–0.05 mm fractions increased by 14.8%, 19.8% and 18.7% (10–20 cm depth), in B1, B2 and B3, respectively. Our findings suggest biochar application at 30 t ha^?1 could improve structural stability and sequestration of TOC and TN in Albic soils.