A coat protein transgene from a Scottish isolate of potato mop-top virus mediates strong resistance against Scandinavian isolates which have similar coat protein genes

Resistance tests were made on seedlings of transformed lines of Nicotiana benthamiana which contain a transgene encoding the coat protein (CP) gene of a Scottish isolate of potato mop-top virus (PMTV). This transgene has been reported to confer strong resistance to the PMTV isolate from which the transgene sequence was derived and also to a second Scottish isolate. Plants of lines of the transgenic N. benthamiana were as resistant to two Swedish and two Danish PMTV isolates as to a Scottish isolate, and of five lines tested, greater than 93.5% of transgenic plants were immune. The coat protein gene sequences of these four Scandinavian isolates were very similar to those of the two Scottish isolates. The greatest divergence between the isolates was three amino acid changes and there was less than 2% change in CP gene nucleotide sequence. It is concluded that the PMTV CP transgene used in these experiments could confer resistance against isolates from different geographical areas because it is becoming apparent that the CP genes of PMTV isolates are highly conserved.     

玉米青贮与花生秧配比对奶牛瘤胃中花生秧降解特性的影响

本试验旨在研究玉米青贮与花生秧配比对奶牛瘤胃中花生秧降解特性的影响。选择4头体重、生理状态、生产性能相近,装有永久瘤胃瘘管的中国荷斯坦奶牛,分别饲喂含有玉米青贮与花生秧不同配比的全混合日粮(TMR),3种TMR中玉米青贮与花生秧的干物质(DM)配比分别为3.9∶1.0(A组)、1.2∶1.0(B组)、0.4∶1.0(C组)。试验分3期进行,依次进行A、B、C组试验。每期预试15 d,采样期4 d;共57 d。采用尼龙袋瘤胃降解技术测定花生秧在奶牛瘤胃中DM、粗蛋白质(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的72 h瘤胃降解率,并求得目标养分的动态降解参数及有效降解率。结果表明:1)花生秧的DM在瘤胃中有效降解率为56.49%~59.62%,CP为40.45%~47.36%,NDF为33.26%~35.20%,ADF为36.31%~37.45%。2)B组DM的有效降解率显著高于C组(P0.05),极显著高于A组(P0.01);B、C组的CP有效降解率显著高于A组(P0.05)。3)B、C组的NDF快速降解部分含量显著高于A组(P0.05);3种TMR对花生秧粗NDF和ADF有效降解率无显著影响(P0.05)。由此可见,花生秧具有较高的饲用价值。本试验条件下,玉米青贮与花生秧DM配比为1.2∶1.0时,可有效提高花生秧DM和CP的瘤胃降解率。     

我国西番莲的研究状况浅析

采用文献计量分析方法,通过对近30年在刊物上发表的有关西番莲研究文献的类型、年限分布、刊物分布等方面进行计量分析研究,以揭示我国西番莲的研究现状。     

土壤处理防治烟草病虫害的效果

在偏酸性土壤中施用石灰及硫酸铜进行土壤消毒处理,结果表明,土壤处理后对烟叶各生育期的农艺性状无明显毒害作用,在产量及产值上无明显不良影响.在抑制花叶病的发生上有较好的减轻作用,对后期赤星病的发生有明显的抑制作用,可作为高山烟区赤星病综合防治的重要措施之一.     

基于图像识别的农产品品质无损检测

农产品外观颜色在一定程度上反映其内在品质,如破损、霉变、成熟度等.从农产品外观颜色的局部区域及全局区域两方面,介绍了根据农产品外观颜色进行无损检测及判断其品质的不同方法.     

6类9种杀虫剂对稻飞虱的田间效果综合评价

水稻稻飞虱是我国和许多亚洲国家当前水稻生产中最主要的害虫,也是湖北省水稻生产上的主要迁飞性害虫之一。近几年来我省连续特大发生。特别是2006年。为了明确防治稻飞虱当家农药品种和不同剂型的田间实际防治效果,选择高效、环保、低毒和安全的农药品种推广应用,我们于2006年     

Nutrient limitations to bacterial and fungal growth during cellulose decomposition in tropical forest soils

Nutrients constrain the soil carbon cycle in tropical forests, but we lack knowledge on how these constraints vary within the soil microbial community. Here, we used in situ fertilization in a montane tropical forest and in two lowland tropical forests on contrasting soil types to test the principal hypothesis that there are different nutrient constraints to different groups of microorganisms during the decomposition of cellulose. We also tested the hypotheses that decomposers shift from nitrogen to phosphorus constraints from montane to lowland forests, respectively, and are further constrained by potassium and sodium deficiency in the western Amazon. Cellulose and nutrients (nitrogen, phosphorus, potassium, sodium, and combined) were added to soils in situ, and microbial growth on cellulose (phospholipid fatty acids and ergosterol) and respiration were measured. Microbial growth on cellulose after single nutrient additions was highest following nitrogen addition for fungi, suggesting nitrogen as the primary limiting nutrient for cellulose decomposition. This was observed at all sites, with no clear shift in nutrient constraints to decomposition between lowland and montane sites. We also observed positive respiration and fungal growth responses to sodium and potassium addition at one of the lowland sites. However, when phosphorus was added, and especially when added in combination with other nutrients, bacterial growth was highest, suggesting that bacteria out-compete fungi for nitrogen where phosphorus is abundant. In summary, nitrogen constrains fungal growth and cellulose decomposition in both lowland and montane tropical forest soils, but additional nutrients may also be of critical importance in determining the balance between fungal and bacterial decomposition of cellulose.     

水稻条纹叶枯病暴发成因与治理对策

通过近几年的研究和防治实践,在2006年栽培制度和气候条件适宜,灰飞虱大发生的情况下,通过综合应用各项控虫防病措施,麦田、水稻秧田、移栽大田全程用药,有效扑了灭灰飞虱的危害,控制了条纹叶枯病的发生流行。     

扬麦14号群体动态对产量结构的影响分析

通过试验资料分析得出:除退化小穗与各生育阶段苗情的线性相关性没有通过显著性检验外,其它穗粒结构指标与不同生育阶段苗数都已通过相关检验。可通过数值模拟分析,确定一个苗数区间,更有利于实际生产管理和应用。     

昆虫性信息素群集诱杀技术对斜纹夜蛾的控害研究

试验结果表明,与常规防治相比,昆虫性信息素群集诱杀技术具有安全、环保、长效的控害作用,防治效果与成本均优于常规防治;不同放置密度、高度对斜纹夜蛾诱杀效果有差异,高密度区诱蛾量及对减少田间落卵量、压低田间虫源等作用方面表现较好,但成本相对较高,诱捕器悬挂高度以距离地面80~100cm诱蛾效果较好,挂放10d内及发蛾高峰期诱蛾效果明显。