用孕酮阴道栓治疗乏情牛的试验

用孕酮阴道栓治疗乏情牛,一至三天内同期发情率为89.6%。72头牛采用冷冻精液授精,第一情期受孕率为33.3%,笫二情期受孕率为19.4%。证明孕酮阴道栓治疗乏情牛是有效的。     

Neural network prediction of performance parameters of an inclined plate seed metering device and its reverse mapping for the determination of optimum design and operational parameters

Seed planting equipment with inclined plate seed metering devices is the most commonly used equipment for planting of peanut crop in India. For obtaining the high yield, it is very essential to drop the peanut seeds in rows maintaining accurate seed rate and seed spacing with minimum damage to seeds during metering. This mainly depends on forward speed of the planting equipment, rotary speed of the metering plate and area of cells on the plate. The relationship between these factors and the performance parameters viz., seed rate, seed spacing and percent seed damage can be established using regression analysis. But they may not be very accurate and may pose difficulty in the determination of inputs for a set of desired outputs (reverse mapping). Hence, an attempt has been made in this paper to develop the feed forward artificial neural network (ANN) models for the prediction of the performance parameters of an inclined plate seed metering device. The data were generated in the laboratory by conducting experiments on a sticky belt test stand provided with a seed metering device and an opto-electronic seed counter. The generated data was used to develop both statistical and neural network models. The performance of the developed models was compared among themselves for 4 randomly generated test cases. The results show that the ANN model predicted the performance parameters of the seed metering device better than the statistical models. In order to determine the optimum forward speed of the planting equipment, peripheral speed of the metering plate and the area of cells on the plate to obtain the recommended seed rate of 33.33 seeds/m², seed spacing of 100 mm and percent seed damage of 0.2% with 100% fill of the cells, a novel technique of reverse mapping using ANN model was followed. It was observed that the optimum forward speed of the planting equipment and optimum area of cells on the metering plate had good correlation with size of seed. Linear regression equations were developed to predict the optimum forward speed of the planting equipment and optimum area of cells on the metering plate using the size of seeds as independent parameter. The peripheral speed of the metering plate of 0.237 m/s was found to be optimum for the size of seeds in the range of 95.42-123.01 mm². However, the results need to be verified by conducting planting operation under actual field conditions.     

向川安瘿蜂和寄生性长尾小蜂共生菌Wolbachia的检测

Wolbachia是一类胞质遗传共生菌，能调控被其感染宿主的生殖方式。以向川安瘿蜂虫瘿中获得的向川安瘿蜂和其寄生的长尾小蜂为材料，使用Wolbachia的wsp基因特异引物，通过PCR扩增向川安瘿蜂和长尾小蜂Wolbachia的wsp特异片段，以邻位相连法构建Wolbachia的wsp基因的分子系统树。结果表明：向川安瘿蜂和长尾小蜂均感染了Wolbachia；因二者感染Wolbacia的株系Wa和Wb的wsp序列差异大，不能认定在寄生的长尾小蜂和宿主向川安瘿蜂间存在Wolbachia的水平传播。     

基于土壤液化原理的荸荠采收船的研究

荸荠的生长环境特殊，收获仍旧采用传统手工挖掘，劳动效率低，劳动强度大，难以挖净，而薯类收获机械又难以适应水田荸荠的收获，通过对荸荠生长地的土壤成分分析，基于土壤液化原理，搭建了小型实验平台，对荸荠挖掘机理进行了试验模拟。提出了一套适用于水田作物荸荠机械挖掘、筛分的流程，并对挖掘原理进行了实验探究。根据实验数据分析，获得了影响荸荠收获的主要因素。研究表明利用土壤液化原理可以使砂壤土液化，为该原理用于荸荠采收提供依据，为荸荠挖掘机样机的试制提供设计参考。     

拖拉机传动系加载磨合台测控技术研究

介绍拖拉机传动系加载磨合台的系统构成、软件设计、功能与创新之处。本磨合台采用电封闭结构,驱动电动机驱动被试传动系,被试传动系带动加载电动机,加载电动机产生的电能又返回驱动电动机,实现能量的循环利用。软件设计保证用户操作简单、稳定可靠。     

间接地下滴灌导水装置规格参数模型研究

根据灌水过程中质量守恒原理建立了导水装置规格(直径,高度)参数求解模型,该模型中综合考虑了滴头流量、灌水定额、土壤水力特性参数以及活动水位等因素对导水装置规格的影响。通过室内恒定水头积水入渗试验的设计和研究,定量化了土壤水力特性参数对导水装置规格参数模型的作用,并研究了导水装置内水位深度的动态变化规律。结果表明,当忽略导水装置内积水深度的动态变化对土壤水力特性参数的影响时,与一维垂直入渗规律相似,导水装置内积水入渗累计入渗量与时间的关系可用菲利普公式进行拟合,但在土壤类型一定时,间接地下滴灌的参数渗吸系数S和稳定入渗速率if还与土壤上方的积水面积有关。当滴头流量大于土壤入渗速率时,导水装置内开始产生积水,且积水深度处于不断上升的过程。该模型的建立为间接地下滴灌导水装置规格的选取提供了理论指导。     

Before the Cows Come Home:

No abstract available for this article.     

Mechanical transmission of maize rayado fino marafivirus (MRFV) to maize and barley by means of the vascular puncture technique

Maize rayado fino marafivirus (MRFV) was mechanically transmitted to kernels of three Costa Rican maize cultivars by the vascular puncture technique. A transmission rate of up to 43.2% was obtained for cultivar HC-57. The rate of MRFV transmission to maize was possibly affected by the morphology of the kernel, which may influence physical access to the vascular tissue after water imbibition. Transmission to maize was confirmed by western blot and immunosorbent electron microscopy. By slight modifications of the procedure, MRFV was also transmitted to barley. This is the first report of MRFV infecting a species outside the supertribe Andropogonodae. Virus infection and replication in barley were confirmed by RT-PCR detection of MRFV RNA and by detection of the virus by ELISA.     

Tobacco rattle virus serotypes and associated nematode vector species of Trichodoridae in the bulb-growing areas in the Netherlands

Soil samples from the coastal bulb-growing areas in the provinces of North- and South-Holland and the North-East Polder in the Netherlands were examined for trichodorid nematodes and tobacco rattle virus (TRV) serotypes. At least one of a total of eight species of Trichodoridae, of whichParatrichodorus pachydermus was most prevalent, was found in 93% of the samples from the provinces of North- and South-Holland and TRV, including four serotypes, was obtained from 49% of these samples. In the North-East Polder one of three species of trichodorids, of whichP. teres occurred most frequently, was present in 72% of the samples, and TRV of one serotype was obtained from 28% of these samples. The TRV isolates recovered from these samples reacted serologically with one of four antisera to strains of TRV. Virus transmitted byP. pachydermus reacted to the PRN-, byTrichodorus viruliferus to the RQ-, byP. teres to the N5- and byT. similis, to the TS-antiserum, respectively.     

Distribution and properties of geographically distinct isolates of sugar beet yellowing viruses

From a total of 261 yellow sugarbeet leaves collected from 10 countries representing three continents, the incidence and distribution of strains of Beet mild yellowing virus (BMYV), Beet chlorosis virus (BChV) and Beet yellows virus (BYV) were analysed using serological and molecular methods. BMYV was found in all countries except Greece, and more frequently in the northern and western areas of Europe, whereas BYV predominated in Turkey, Spain, Greece, the USA and Chile. BChV, originally found in the USA and the UK in 1989, was identified in France, Spain, the Netherlands and Chile. Nine sugar beet poleroviruses, plus a reference isolate of Turnip yellows virus (TuYV, syn. Beet western yellows virus ), were further characterized and compared. Isolates obtained from sugar beet infected this species, but not oilseed rape or lettuce; all isolates except one infected Capsella bursa-pastoris . The coat-protein sequences of these isolates were highly similar, with the consensus sequence representing 89% of nucleotide residues. Within the coat-protein gene, two regions were identified that could represent specific epitopes to which monoclonal antibody BYDV-PAV-IL-1 could bind; this antibody is used to distinguish beet poleroviruses in ELISA. Comparison of the sequences at the 5' end showed that sequence homology existed only between isolates with the same host range. The first sequence data of polerovirus isolates from Chile are presented, showing that the coat protein and the 5' end of their genomes are highly similar to those of BMYV isolates found in Europe. Chilean polerovirus isolates may have been imported from the northern hemisphere in sugar beet breeding material.