钾肥和硅肥对油用亚麻茎秆抗倒伏特性的影响

为了优化油用亚麻抗倒伏的肥料运筹措施,以‘陇亚11号’和‘定亚23号’为试验材料,通过裂区设计,研究了钾肥（不施钾、52.5 kg K₂O/hm²和105 kg K₂O /hm² 3个水平）和硅肥（不施硅和90 kg SiO₂/hm² 2个水平）用量对油用亚麻茎秆形态学、力学抗倒伏特性及产量的影响。结果表明：‘陇亚11号’的株高、重心高度及茎粗、壁厚、抗折力均显著大于‘定亚23号’,茎秆形态学及力学抗倒伏特性的综合影响下,‘陇亚11号’较‘定亚23号’倒伏率提高21.24%而产量降低9.43%。钾肥显著改善了抗倒的茎秆表观形态学特性,施钾后茎粗、壁厚、茎秆抗折力、抗倒伏指数提高而株高和重心高度降低,千粒重和籽粒产量分别提高7.35%和9.34%。硅肥对茎秆形态学、力学特性及籽粒产量均无主效应,但硅肥与钾肥的互作使茎粗显著增加。抗倒伏指数与茎粗、壁厚呈显著正相关,与株高、重心高度呈显著负相关。品种间的茎秆抗倒伏特性差异较大,施用钾肥显著改善了抗倒的茎秆表观形态学特性,优化了茎秆机械性能,增强了油用亚麻的抗倒伏能力;供钾量较低时,硅肥与钾肥对茎粗的互作正效应明显。     

增温加氮对两种不同来源加拿大一枝黄花子一代生长的影响

为探讨模拟气候变暖(增温2℃)和大气氮沉降(4 g·m-2·a-1)对入侵植物子代生长的影响,以中国和北美两种来源的加拿大一枝黄花子一代为研究对象,研究了子一代幼苗的生长和生物量分配的响应.结果表明:(1)增温降低中国来源加拿大一枝黄花的地上生物量,但提高其根冠比,增温降低北美来源加拿大一枝黄花的根冠比;(2)与北美来源加拿大一枝黄花相比,加氮对中国来源加拿大一枝黄花叶片数、地下生物量和总生物量的促进作用更大;(3)加氮促进加拿大一枝黄花地上生物量、地下生物量和总生物量的积累,但增温减缓了这种促进作用.这些结果表明,气候变暖可能会部分抵消氮沉降对加拿大一枝黄花子一代幼苗生长的促进作用.     

Climate change will affect the ability of forest management to reduce gaps between current and presettlement forest composition in southeastern Canada

Landscape Ecology - Forest landscapes at the boreal–temperate ecotone have been extensively altered. Reducing the gap between current and presettlement forest conditions through...     

The impact of external knowledge sourcing on innovation outcomes in rural and urban businesses in the U.S.

This paper examines the relationship between external knowledge sourcing and a diverse set of innovation outcomes in rural and urban establishments in the U.S. Existing studies in the broader knowledge management literature principally examine firms in a single industry, overwhelmingly rely on patent data to proxy for innovation, and cannot account for the innovations of businesses in rural American markets. By addressing these limitations using data from the 2014 Rural Establishment Innovation Survey of the USDA's Economic Research Service, this research provides novel insights into how externally acquired knowledge by American establishments may support innovation. Results of the analysis suggest that external knowledge sourcing may specifically promote product, process, and green innovation in U.S. firms. While collective results when external sources of information are divided by industry orientation fail to show that sources outside of a firm's industry play a dominant role in the innovation processes of American establishments in general, findings provide evidence for an outsized impact of these relationships within rural establishments specifically and suggest that external knowledge sourcing from extra‐industry organizations is most critical for promoting successful innovation in rural firms. Results additionally indicate that knowledge sourcing from non‐local organizations may be more important for supporting innovation in rural compared to urban markets.     

Spatial–temporal evolution of the port–hinterland relationship: A case study of the Midstream Yangtze River,China

Most scientific attention on port studies centers on deep sea ports, especially container ports. In this paper, in contrast, attention is focused on the spatial–temporal development of inland waterway ports on the Midstream Yangtze River from 2001 to 2013. The aim of this study is to assess two relevant and complementary questions of the hinterland evolution: its geographical extent and the coordination relationship with the inland port. To conduct the study, it was necessary to first identify the boundaries of the ports' hinterlands within the given timeframe. Then, the coupling coordination degree model was introduced to explore the underlying relationship between the port service and hinterland economy. Furthermore, to better depict the intricate economic characteristics of the hinterland, the development stage theory was applied in the models. The results highlight the emergence of a discontinuous hinterland at Wuhan Port and its reinforcement of primacy with respect to fierce hinterland rivalry. It also demonstrates that an interplay between major ports and their corresponding hinterlands evolves from the transitional stage, characterized by lagging port service, to the multi‐stage, wherein the supply of ports partly outstrips hinterland demand.     

Development of colchicine‐induced tetraploid St. Augustinegrass (Stenotaphrum secundatum) lines

St. Augustinegrass is well suited for lawns and commercial landscapes. While many genotypes are cross‐fertile, all cultivars are propagated vegetatively in sod production. To ensure varietal purity, development of sterile triploid hybrids by crossing tetraploid and diploid genotypes has been successfully used in other warm‐season turfgrasses. Applying this model in St. Augustinegrass would be beneficial to sod producers and turf managers who require purity for certification and uniformity for performance, respectively. This study was conducted to develop colchicine‐induced tetraploid lines of St. Augustinegrass. Seeds of cultivar ‘Raleigh’ were treated with four colchicine concentrations at four exposure times. A non‐treated control was included among the treatments. Seedlings that germinated were screened for genome size changes using flow cytometry. Line DSA 13005 and two progeny lines derived through selfing, DSA 16001 and DSA 16016, were corroborated as tetraploids (2n = 4x = 36) through chromosome counts. These lines will be used in future breeding efforts to attempt development of sterile triploid cultivars of St. Augustinegrass.     

紫花槭秋季叶色表达转录组初步分析

为了丰富紫花槭转录组数据,进一步开展紫花槭秋季叶片呈色机制研究.本研究以紫花槭秋季转色期三个阶段(前期,中期,后期)叶片为材料,采用高通量测序技术进行转录组初步分析.转录组数据共获得50501条Unigene,有35316条Unigene在数据库中得到注释,其中NR数据库中注释到的Unigene数量最多,共35024条,占69.4％.在注释到的物种中,紫花槭比对的Unigene与甜橙(Citrus sinensis)相似度最高,共有4290条,占12.25％.紫花槭转录组中的Unigene根据GO功能可分为生物学过程、细胞组分和分子功能3大类,共有25375条,其中生物学过程的基因最多,主要聚集于代谢过程和细胞过程等.基于Unigene库的基因结构分析,其中SSR分析共获得12711个SSR标记,占Unigene总数的36％.SSR位点共包含150种重复基元,单碱基重复所占比例最高(7184个,61.86％),四碱基重复、五碱基重复和六碱基重复所占比例较低.Unigene库中共有328239个SNP位点,发生频率为1/190 bp,SNP位点分为转换和颠换两种类型的碱基替换方式,其中碱基转换位点213787个(65.13％),碱基颠换位点114452个(34.87％),碱基转换类型发生频率高于颠换类型.6种单碱基变异中,2种转换类型A/G、C/T的发生频率分别为33.03％和32.10％;4种颠换类型中A/T发生频率最高,为11.52％;C/G发生频率最低,为5.79％.紫花槭转录组秋季叶色表达的转录组分析,可为紫花槭叶色基因调控、定向分子育种和培育彩叶新品种提供研究提供基础的数据信息.     

花生栽野种间杂交异源多倍化早期世代基因表达变化分析

为了进一步认识花生种间杂交异源多倍体进化过程中的基因表达变化规律,采用cDNA-HFO-TAG技术,研究花生种间杂交组合(四倍体栽培种‘仲恺花4号’×二倍体野生种Arachis. diogio)杂种F_1和早期多倍体世代S0~S3的基因表达变化情况。14条HFO-TAG引物共扩增出121条cDNA片段,其中差异片段84个,主要包括三种类型:亲本转录物完全沉默(3个),双亲转录物在后代部分材料中沉默(59个)和新转录物激活(22个),上述变化在F1代即开始发生。筛选其中大小为500~2 000 bp的35个TDFs进行克隆测序,有27个和NCBI数据库中已录入的基因具有较高的相似性,包括抗逆相关基因(10条)、未知功能蛋白基因(8条)、能量与代谢相关基因(7条)和转录因子相关的基因(2条)。这些研究结果进一步表明在花生种间杂交异源多倍化早期发生着快速、剧烈的基因表达变化,从中获得的差异基因片段,有助于了解花生属种间杂交异源多倍化早期分子机制变化,这对有效利用野生花生种质优异基因具有重要意义。cDNA-HFO-TAG技术简单、有效且实用,完全适用于花生属基因表达变化研究,可以作为花生属及其它物种基因表达变化分析技术的有效补充。     

河北省棉田绿盲蝽绿色防控技术体系构建

为了构建科学合理、可操作性强的河北省棉田绿盲蝽绿色防控技术体系，于2011－2015年在河北省沧州植棉区开展了棉田绿盲蝽绿色防控技术研究，包括色板诱杀、性信息素、频振式杀虫灯和高效生物农药应用等，并逐步构建了针对棉田绿盲蝽的绿色防控技术体系。根据相关研究发现，该绿色防控技术对棉田绿盲蝽有较好的防治效果，与常规防治区相比，减药控害成果显著。     

Silage and total mixed ration hygienic quality on commercial farms: implications for animal production

Implications of silage hygienic quality for animal production were investigated on forty‐five dairy farms in South West England. Samples of grass and maize silages and of total mixed rations (TMR) were obtained together with information on silage technology, herd size and animal production. Samples were analysed for mycotoxins, bacteria, yeasts, moulds and chemical composition. Thirteen mycotoxins were assayed, but none were detected in the samples of grass silage. However, mycotoxins were found in 0·9 of all maize and other silage samples, with deoxynivalenol and zearalenone predominating. There was no relationship between total mycotoxin concentration and mean lactation milk yield per cow. Enterobacteria counts tended to be higher in maize silage than in grass silage and higher still in TMR – a cause for concern. There were no relationships between mould counts and mycotoxin concentrations in silages, implying that mycotoxins may have been produced in the field pre‐ensiling.