美国西北部59个小麦品种（系）抗条锈病基因分子检测及对中国条锈菌系抗性鉴定#br#

 【目的】了解59份美国西北部小麦品种（系）对中国当前条锈菌流行小种的抗性水平,分析其抗病基因的存在情况,为培育中国抗条锈病新品种提供资源和依据。【方法】选用中国小麦条锈菌优势小种条中31号、条中32号和条中33号对大部分具有高温成株抗性的美国59份小麦品种（系）苗期及成株期进行抗性接种鉴定,利用与当前有效的全生育期抗性基因Yr10、Yr15、成株抗性基因Yr18、高温成株抗性基因Yr39紧密连锁的分子标记对供试材料进行分子检测。【结果】抗性鉴定表明,Expresso、02W50076、ACS52610、WA008012、WA008018等5份材料苗期与成株期对条中31号、条中32号和条中33号混合菌均表现为抗病,属于全生育期抗病品种。 33份材料苗期表现感病而成株期表现抗病,属于成株期抗病品种。分子检测发现59份材料均不含有Yr10;含有Yr15、Yr18和Yr39的材料分别为12、33和29份,占20%、56%和49%。【结论】Yr18、Yr39在美国西北部小麦品（系）中的分布较普遍,并且大部分可以抵抗中国当前流行的条锈菌生理小种,可应用这些抗性材料配制中国小麦抗条锈病新品种。     

北美海棠品种在不同栽植模式下的生长和生理响应研究

为了探索北美海棠(North American Begonia)对不同栽植模式的响应,提升北美海棠在园林绿化中的栽植广度。研究了6个北美海棠品种在5种栽植模式下的生长和生理响应。结果表明,从不同品种对栽植模式的响应来看,栽植模式1要优于其他栽植方式;其中露易莎对各种栽植方式适应性最好,其次是罗宾逊、凯尔斯、丰花;各北美海棠品种在园林绿化应用中栽植高度以小于地面40 cm为宜;光合特性差异较小的品种有高原之火、丰花、罗宾逊、凯尔斯;高原之火的成活率最高,为100%,其次是凯尔斯、露易莎、丽丝,成活率为80%。凯尔斯、高原之火植株的叶片发病率较低,丰花、丽丝的植株叶片虫害较轻。     

美国、日本奶业相关补贴政策与奶农开展乳制品加工的启示

美国与日本均已形成了一系列完整紧密、运转高效的奶业政策体系,并通过各种合作组织提升奶农在奶业产业链利益分配中的话语权.这两个国家在奶农开展乳制品加工方面的成功案例,对于我国完善产业政策体系、健全利益联结机制及推进一二三产业融合发展等方面具有重要意义.     

Anthropogenic effects on soil quality of ancient agricultural systems of the American Southwest

Soil studies of ancient agricultural fields contribute to research on long-term human–environmental relationships and land use sustainability. This kind of research is especially applicable in desert landscapes of the American Southwest because: (1) soil formation is slow enough that cultivation effects persist for centuries to millennia; (2) many ancient fields in valley margins have remained uncultivated since they were abandoned, so long-term soil properties reflect ancient agricultural use; and (3) agricultural features (e.g., terraces, rock alignments and rock piles, and irrigation canals) provide clues for identifying and sampling ancient cultivated and uncultivated soils. Surficial remnants of these field systems persist and remain intact in many cases. Soil studies of ancient and modern American Indian agricultural systems across the Southwest indicate that soil changes are highly variable, ranging from degradation (e.g., organic matter/nutrient decline, compaction), to minimal net change, to enhanced soil quality. Soil changes caused by cultivation can be inferred by comparing soils in agricultural fields relative to reference uncultivated areas in similar landscape settings (that is, space-for-time substitution). Soil response trajectories vary for a number of reasons, such as variability in initial ecosystem conditions, diversity in agricultural methods, variability in the mix of crops and cropping intensity, and environmental sensitivity to alteration (varying resistance and resilience). Studies of rock mulch soils indicate enhanced fertility, with elevated organic carbon, nitrogen, and available phosphorus levels, increased infiltration rates and moisture retention, and no evidence of compaction. By contrast, cultivation effects vary widely for terraced soils. Although numerous studies have focused on irrigation canals, irrigated soils have received far less attention. Soil studies of irrigation systems along the Gila and Santa Cruz rivers of Arizona now underway will help fill this research gap.     

Osteochondrodysplasia in Scottish Fold cross-breed cats

Two Scottish Fold mixed cats are described in this report. Case 1 is a mixed Scottish Fold and Munchkin cat. Extremities of this cat resembled the Munchkin cat, while the ear pinna were folded forward like the Scottish Fold cat. Case 2 is a mixed Scottish Fold and American Curl cat. The ear pinna were curled caudally like the American Curl. Severe exostosis in the hind leg was observed in radiographs taken around one year of age in both cats. Both cats were dominant homozygous for c.1024G>T of the transient receptor potential vanilloid 4 gene, responsible for osteochondrodysplasia in the Scottish Fold cat. Cross breeding with Scottish Fold cats could produce unknown phenotypes, and should be avoided.     

芦荟提取液抗菌效果研究

[目的]为芦荟在食品行业中的开发利用提供理论依据。[方法]以苯甲酸钠为对照,采用滤纸片法,研究美国库拉索芦荟(Aloe barbadensis Miller.)叶根部、叶中部、叶尖部的提取液对多种常见菌种的抑制作用及其热稳定性。[结果]不同部位芦荟提取液对金黄色葡萄球菌、大肠杆菌、黑曲霉都表现出了一定的抑菌作用,可媲美苯甲酸钠,对酿酒酵母的抑菌作用不是很明显。对于各种菌种来说,芦荟提取液抑菌作用的热稳定性良好,即使经过热处理也仍然保留良好的抗菌能力。[结论]芦荟提取液对多种细菌和霉菌有较强的抑菌作用,但对酿酒酵母没有抑制作用。     

美国黑李引种试验

对美国黑李进行引种试验,结果表明。美国黑李适应本地区气候条件生长,并筛选出早熟品种李王、中熟品种黑琥珀、晚熟品种黑宝石和皇家宝石等4个优良品种,其3年平均树高、地径、冠幅、单株产量和产量分别达到3．40m、5．18m、1．74m^2、22．3kg、1255kg／667m^2,比对照提高1．3倍、1．48倍、1．6倍、7．88倍和7．94倍,充分显现出良种的优势,值得推广。     

美国白蛾——城市森林的大敌

美国白蛾是世界性检疫害虫,在我国北方疫区较广,疫情严重危及城市生态安全,文章根据北京、唐山等地防治经验,总结了美国白蛾生物学特性及综合防治方法。       

试论美语和英语的差异及其由来与发展

简明而又系统地论述美国英语同英国英语在读音、拼写、用词和语法方面的差异,并从社会和时代发展的观点及美国历史变迁和经济发展的视角,分析了产生这些差异的主要原因,展望了两种英语相互弥补、融为一体、形成一种标准英语的乐观前景.     

美国黑莓的主要品种与栽培技术

本文重点介绍美国黑莓的主要栽培品种、栽培及加工利用技术并探讨黑莓的市场前景以指导我国黑莓的引种栽培。