Soybean Genotypic Variation for Nitrogen Fixation

Eighteen soybean ( Glycine max [L.] Merr) cultivars from maturity groups V and VI were screened with two Bradyrhizobium japonicum strains (USDA 110 and TAL 378) in the greenhouse to determine N₂ fixation (C₂H_2: reduction) rates. Antibiotic resistant markers were used for observing nodule occupancy. Cultivars L.-76-0132, PI 159319, Hoberland, Lee, PI 22173 and Centennial showed high nitrogenase activity of 6.25, 5.54, 17.43, 4.73, 6.94, and 4.81 μM C₂H₄/Pl/hr, respectively. Cultivars PI417419, PI 230978, Ogden , and FC 31665 showed low nitrogenase activity of 1.51, 0.80, 0.62 and 0.94 μM C₂H₄/Pl/hr, respectively. The data from this screening experiment suggest that the N₂ fixation varied among genotypes and all the nodules were occupied by the inoculated strains only. Rhizobial strain effect was observed among soybean cultivars (MGVI).     

热压机活动横梁结构刚度理论分析

压机是人造板工业中的重要设备之一,多层压机的出现大大地提高了劳动生产率。在多层热压机中,活动横梁是压机主要运动部件,它由肋板和压板焊接而成,并与油缸活塞杆联接传递压力,目前在人造板生产中,要保证压力场的均匀,人造板面的平整,要求活动横梁有足够的强度和刚度,通常压机设计时,对活动横梁往往采取类比的方法,使得活动横梁结构尺寸增大,造成了材料的浪费。为此,本文详细分析了热压机活动横梁肋板的合理排列,尺寸的选择与刚度的关系,其结果有一定的实用价值。     

Multiple rib fracture in a neonatal foal using a nylon strand suture repair technique

OBJECTIVES: To report rib fracture repair using the Securos Cranial Cruciate Ligament Repair System (SCCLRS; Securos Veterinary Orthopedics, Charlton, MA) in a neonatal foal. STUDY DESIGN: Case report. ANIMALS: A 1-day-old Standardbred foal with fracture of left ribs 2-9. METHODS: Four days after admission the foal was anesthetized and rib fractures were repaired using open reduction and the SCCLRS. RESULTS: Rib fractures were successfully stabilized and the foal was discharged 7 days postoperatively without further complications. CONCLUSIONS: The SCCLRS provided a straightforward, effective method of rib fracture repair in neonatal foals. CLINICAL RELEVANCE: Effective rib fracture repair in neonatal foals can be achieved with the SCCLRS.     

淡紫紫孢菌PLHN与甲氨基阿维菌素苯甲酸盐减量复配防治象耳豆根结线虫

象耳豆根结线虫Meloidogyne enterolobii严重威胁热带农业生产,迫切需要寻求一种兼具生物防治和化学农药减施高效双重优势的绿色防治方法。本研究通过杀线剂毒力测定和生防菌耐药测定,设计系列药菌复配组合并筛选出对象耳豆根结线虫活性好的复配方案。结果表明:3%甲氨基阿维菌素苯甲酸盐(甲维盐)微乳剂对淡紫紫孢菌Purpureocillium lilacinum PLHN的菌丝生长、产孢量及孢子萌发的影响均较小,且对象耳豆根结线虫的LC50为0.107 mg/L, LC99为0.792 mg/L,绝对致死浓度为0.8 mg/L。复配组合中甲维盐0.4 mg/L(减量50%)+75% PLHN和甲维盐0.6 mg/L(减量25%)+50% PLHN对根结线虫2龄幼虫和卵的抑杀作用均优于其他组合。盆栽防效表明:0.6 mg/L甲维盐(减量25%)+50%PLHN复配组合的防效最好,对根结形成有一定的抑制作用,防治效果与全量甲维盐相当,并能促进番茄植株的生长;0.6 mg/L甲维盐+25% PLHN和0.4 mg/L甲维盐+75%PLHN次之。甲维盐和淡紫紫孢菌PLHN的复配使用,不仅甲维盐能减量25%～50%,还能弥补生物防治稳定性较弱、持效期不长等不足,是植物线虫病防治的可选策略之一。     

Transvaginal ultrasound-guided aspiration of unilateral twin gestation in the mare

Embryo reduction of unilateral twin vesicles is normally successful before fixation of the vesicles. After fixation, however, it becomes a challenge, and the later in the gestation period that the reduction is performed, the greater the challenge. One therapy to reduce a twin into a singleton pregnancy is the transvaginal ultrasound-guided aspiration (TUGA) of one of the vesicles. The results of 35 unilateral twin reductions by TUGA are discussed in this paper and possible negative influences of age, parity and days pregnant are analysed statistically.     

Will Culling White‐Tailed Deer Prevent Lyme Disease?

White‐tailed deer play an important role in the ecology of Lyme disease. In the United States, where the incidence and geographic range of Lyme disease continue to increase, reduction of white‐tailed deer populations has been proposed as a means of preventing human illness. The effectiveness of this politically sensitive prevention method is poorly understood. We summarize and evaluate available evidence regarding the effect of deer reduction on vector tick abundance and human disease incidence. Elimination of deer from islands and other isolated settings can have a substantial impact on the reproduction of blacklegged ticks, while reduction short of complete elimination has yielded mixed results. To date, most studies have been conducted in ecologic situations that are not representative to the vast majority of areas with high human Lyme disease risk. Robust evidence linking deer control to reduced human Lyme disease risk is lacking. Currently, there is insufficient evidence to recommend deer population reduction as a Lyme disease prevention measure, except in specific ecologic circumstances.     

华南双季稻化肥减施增效综合技术模式及技术规程

水稻生产过程中化肥的不合理施用,带来了农产品生产成本增高、农田环境污染等问题,影响水稻生产的可持续发展。于2018—2020年,在单项技术研究基础上,开展本研究,旨在形成适合华南双季稻区的化肥减施增效综合技术模式。研究选用高产、高效水稻品种（双高）,同时优化氮、磷、钾肥的比例结构以及基蘖肥的比例结构（双优）,在化肥中补充施入海藻精和微生物菌剂（双补）,合理平衡移栽密度与肥料施用量、水气平衡方法水分管理（双平衡）的方法。2019—2020年在象州和宾阳县进行技术示范,化肥减量综合技术示范区的化肥施用量比对照减少化肥用量17%（包括氮、磷、钾肥）基础上,平均稻谷产量分别为6479.76 kg/hm²、6755.62 kg/hm²,其稻谷产量分别比对照增产2.30%和6.55%。本研究总结了华南双季稻化肥减施增效技术规程。     

茶园土壤N2O排放的影响因素及减排措施

茶园土壤通过微生物作用释放大量氧化亚氮(N₂O),因此需迫切了解茶园土壤N₂O产生机制及影响因素,以期为茶园土壤N₂O减排提供理论依据。从氮源、有机质、pH、水分、温度、质地等角度对茶园土壤N₂O排放的影响进行综述,提出相应的N₂O减排措施。对以上影响因素阐述发现：反硝化作用对茶园土壤N₂O排放的贡献较大;氮肥施用、土壤理化性质、气象因子等是茶园土壤N₂O排放的关键因素。施用缓释氮肥、氮肥深施、采用氮肥推荐施用量、养分有机替代技术能降低茶园土壤N₂O排放。     

环境湿度对白桦木材尺寸稳定性的影响

对白桦木材在不同环境湿度下的尺寸稳定性进行了试验研究,试验表明:白桦小试件的含水率随环境湿度变化的时间较短,在正常的湿环境中1~2d内就与周围的环境达到平衡;较大尺寸的家具拼板材在干燥的环境中解吸速度较慢,需要较长的时间,同样在潮湿的环境中吸湿较慢,要达到与周围的环境相平衡同样需要比小试件更长的吸湿时间。     

关于我国农村参与式扶贫模式的思考

参与式扶贫作为近年来正在探索的农村扶贫开发方式之一，在全国各地开展了大量的试点项目。通过引用陕西柞水县和宁夏盐池县两地的参与式扶贫项目评估数据，论证了我国农村参与式扶贫在针对性、效果、效率及可持续性方面存在的问题，提出了相应的对策，为参与式扶贫模式的进一步推广提供了新的思路。