Advantages of Wild Diploid Solanum Species Over Cultivated Diploid Relatives in Potato Breeding Programs

For breeding programs of the tetraploid potato (Solanum tuberosum), both wild and cultivated diploid relatives are valuable sources of genetic diversity. While both types of germplasm are used in breeding programs, there are several advantages to using wild relatives. Diploid relatives are typically crossed with haploids (2n = 2x = 24) from tetraploid S. tuberosum to improve daylength adaptation. Most haploids are male sterile, so they are typically used as female parents. Cultivated diploids, such as members of the Phureja Group, produce male sterile hybrids when crossed as females to haploids; wild relatives, such as S. tarijense, often produce male fertile hybrids. Tuber yield following crosses of haploids to cultivated or wild relatives is often high. However, cultivated relatives generally produce hybrids with a high set of small tubers; hybrids from wild relatives are variable, but many are similar to cultivars in tuber size and set. While tubers of hybrids from cultivated relatives are typically rough, with deep eyes and raised internodes, those from wild relatives are often smooth. Tuber dormancy in hybrids with cultivated relatives is generally short, while that in hybrids with wild species is longer, allowing for storage over winter. Finally, resistance to several major diseases and stresses has been found in wild species and their hybrids with S. tuberosum haploids. The desirable traits in hybrids are transmitted to tetraploids via unilateral sexual polyploidization (4x × 2x or 2x × 4x crosses in which the diploid parent produces 2n gametes). Wild Solanum species are recommended for use in potato breeding programs as sources of genetic diversity that can be adapted easily following hybridization with S. tuberosum haploids.     

基于凹点搜索的重叠果实定位检测算法研究

为了能够快速准确地计算出生长状态为靠拢或重叠的成熟类圆果实的形心坐标和半径,提出了一种基于凹点搜索的快速定位和检测重叠果实目标的方法.利用色调分量的统计规律实现背景分离,采用链码跟踪法获得单像素果实轮廓,并按步长获取边缘特征点;然后利用N点方向编码差获取边缘凹点,确定凹点群,根据阈值确定分割凹点;最后利用改进的Houg...     

水族的传统农耕文化

孕育于百越母体中的水族稻作农业文明,在水族迁居黔桂边境之后,通过适时的文化调适,不但延续了原先“火耕水耨”的文化传统,更创造了“畲山为田”的梯田开发模式,劳动生产工具和耕作技术体现了历史上他们与百越民族(骆越)的渊源关系,对历史的共同追忆,使人们打破了时空界线,形成了强烈的文化认同感和归属感。     

Linear mixed-effects models for weight–length relationships

Length and weight data are often analyzed in fisheries science to derive a parametric weight–length relationship for estimating biomass and to develop indices of condition for comparing the ‘wellness’ of different populations of fish. However, analysis of such data often ignores the inherent spatial and temporal grouping of the observations, and hence, the data hierarchy. This paper proposes the use of linear mixed-effects models as an effective means of analyzing and comparing weight–length relationships and indices of condition when there are many groups. The use of simple linear regression (where grouping is ignored), ANCOVA (where group effects are incorporated as fixed-effects), and linear mixed-effects models (where group effects are random-effects) are compared using data for Atlantic sea scallops (Placopecten magellanicus). The group means of residuals is proposed as a measure of relative weight or index of population condition. Linear mixed-effects models should be used to analyze grouped data because the variability among groups is ignored in simple linear regression and ANCOVA. Also, it is important that explanatory variables be incorporated in analyses of grouped data because their influence may mask the true differences among groups.     

Detection and genetic characterization of porcine group A rotaviruses in asymptomatic pigs in smallholder farms in East Africa: Predominance of P[8] genotype resembling human strains

Viral enteritis is a serious problem accounting for deaths in neonatal animals and humans worldwide. The absence of surveillance programs and diagnostic laboratory facilities have resulted in a lack of data on rotavirus associated diarrheas in pigs in East Africa. Here we describe the incidence of group A rotavirus (RVA) infections in asymptomatic young pigs in East Africa. Of the 446 samples examined, 26.2% (117/446) were positive for RVA. More nursing piglets (78.7%) shed RVA than weaned (32.9%) and grower (5.8%) pigs. RVA incidence was higher in pigs that were either housed_free-range (77.8%) or tethered_free-range (29.0%) than those that were free-range or housed or housed-tethered pigs. The farms with larger herd size (>10 pigs) had higher RVA prevalence (56.5%) than farms with smaller herd size (24.1–29.7%). This study revealed that age, management system and pig density significantly (p < 0.01) influenced the incidence of RVA infections, with housed_free-range management system and larger herd size showing higher risks for RVA infection. Partial (811–1604 nt region) sequence of the VP4 gene of selected positive samples revealed that different genotypes (P[6], P[8] and P[13]) are circulating in the study area with P[8] being predominant. The P[6] strain shared nucleotide (nt) and amino acid (aa) sequence identity of 84.4–91.3% and 95.1–96.9%, respectively, with known porcine and human P[6] strains. The P[8] strains shared high nt and aa sequence identity with known human P[8] strains ranging from 95.6–100% to 92–100%, respectively. The P[13] strains shared nt and aa sequence identity of 83.6–91.7% and 89.3–96.4%, respectively, only with known porcine P[13] strains. No P[8] strains yielded RNA of sufficient quality/quantity for full genome sequencing. However analysis of the full genome constellation of the P[6], two P[13] and one untypeable strains revealed that the P[6] strain (Ke-003-5) genome constellation was G26-P[6]-I5-R1-C1-M1-A8-N1-T1-E1-H1, P[13] strains (Ug-049 and Ug-453) had G5-P[13]-I5-R1-C1-M1-A8-N1-T7-E1-H1 while the untypeable strain (Ug-218) had G5-P[?]-I5-R1-C1-M1-A8-N1-T1-E1-H? In conclusion, P[6] and P[8] genotypes detected were genetically closely related to human strains suggesting the possibility of interspecies transmission. Further studies are required to determine the role of RVA in swine enteric disease burden and to determine the genetic/antigenic heterogeneity of the circulating strains for development of accurate diagnostic tools and to implement appropriate prophylaxis programs.     

Rickettsial Infection in Animals,Humans and Ticks in Paulicéia,Brazil

A previous study in Paulicéia Municipality, south‐eastern Brazil, reported 9.7% of the Amblyomma triste ticks to be infected by Rickettsia parkeri, a bacterial pathogen that causes spotted fever in humans. These A. triste ticks were shown to be associated with marsh areas, where the marsh deer Blastocerus dichotomus is a primary host for this tick species. During 2008–2009, blood serum samples were collected from 140 horses, 41 dogs, 5 opossums (Didelphis albiventris) and 26 humans in farms from Pauliceia Municipality. Ticks were collected from these animals, from vegetation and from additional wildlife in these farms. Overall, 25% (35/140) of the horses, 7.3% (3/41) of the dogs, 3.8% (1/26) of the humans and 100% (5/5) of the opossums were seroreactive (titre ≥64) to spotted fever group (SFG) Rickettsia spp. Multivariate statistical analysis indicated that horses that were allowed to forage in the marsh were 4.8 times more likely to be seroreactive to spotted fever group (SFG) Rickettsia spp than horses that did not forage in the marsh. In addition, horses that had been living in the farm for more than 8.5 years were 2.8 times more likely to be seroreactive to SFG Rickettsia spp than horses that were living for ≤8.5 years. Ticks collected from domestic animals or from vegetation included Amblyomma cajennense, Amblyomma coelebs, Amblyomma dubitatum, Dermacentor nitens and Rhipicephalus microplus. By PCR analyses, only one pool of A. coelebs ticks from the vegetation was shown to be infected by rickettsiae, for which DNA sequencing revealed to be Rickettsia amblyommii. Ticks (not tested by PCR) collected from wildlife encompassed A. cajennense and Amblyomma rotundatum on lizards (Tupinambis sp), and A. cajennense and A. triste on the bird Laterallus viridis. Our results indicate that the marsh area of Paulicéia offers risks of infection by SFG rickettsiae.     

“茶旅融合”助推茶产业转型升级探研——以湖北邓村绿茶集团为例

面对日趋激烈的市场竞争,广大茶企积极应对,努力探寻茶产业转型升级之路,＂茶旅融合＂助推茶产业转型升级便是这一探索过程中取得的重要成果之一。文章以湖北邓村绿茶集团为例,分析了＂茶旅融合＂协同发展的机缘,总结了＂茶旅融合＂促进茶产业发展的路径,提出了＂茶旅融合＂助推茶产业转型升级的策略,以期对鄂茶产业乃至全国茶产业的可持续发展提供借鉴。     

一株D群链球菌的分离鉴定及耐药性试验

从发病猪的关节液中分离细菌,镜检后确定为链球菌.将该菌株培养后进行分群鉴定、生化试验及耐药性试验.结果表明,分离的细菌为链球菌D群.该菌株对大部分药敏试剂都不敏感,耐药性偏高.     

中粉1号粉蕉引种试验初报

【目的】针对广西粉蕉生产中品种单一、易感染1号生理小种（FOC1）引起的镰刀菌枯萎病问题,开展中粉1号粉蕉引种试验,为广西粉蕉生产提供耐病后备品种。【方法】在广西钦州市钦北区新植地、南宁市坛洛镇（枯萎病疫区）引种中粉1号粉蕉,钦州试验点采用水肥一体化喷灌,坛洛镇试验点采用沟渠灌溉和沟穴施有机肥两种不同的水肥管理模式,研究两种栽培模式下中粉1号的农艺性状、产量性状和对枯萎病的耐病性,以当地粉蕉品种为对照。【结果】钦州试验点、坛洛镇试验点的中粉1号农艺性状和对照粉蕉差异不大;钦州试验点中粉1号产量为41695.5kg/ha,比对照高32.9%;坛洛试验点中粉1号产量为26977.5kg/ha,比对照高15.2%;在新植地和枯萎病疫区,中粉1号枯萎病发病率仅4.49%和7.60%,对照粉蕉发病率分别高达29.00%和38.60%。【结论】中粉1号在广西试种表现良好,适应性强,镰刀菌枯萎病对1号生理小种的耐病性强于本地粉蕉,可在广西香蕉产区进一步示范推广。     

农业龙头企业温氏集团对农村经济社会发展的贡献与启示

以温氏集团为例,从提高农村整体经济收入、推动新农村建设,增加农民收入、提升生活水平,拓宽农民就业渠道、促进村民就业,提升村民养殖技术、提高村民整体素质,改变传统养殖模式、推动养殖产业现代化发展,发展绿色生产、降低环境破坏等方面,分析农业龙头企业对农村经济社会发展的主要贡献.得到企业发展目标应与农村发展目标相互相承,企业发展要以村民发展为前提;企业科技创新能力要持续增强等启示.