The mechanical roles of the clasping leaf sheath in cereals: Two case studies from oat and wheat plants

Stem lodging is a common problem in cereal crop production and a main constraint for grain yield improvement. The leaf sheath that surrounds and protects the hollow internodes of stem could provide the plants with a great physical support. However, this biomechanical function has been ignored for several decades in cereal crops. This study aimed to examine the biomechanical properties of basal stem internodes and lodging susceptibility of the whole plants with or without the clasping leaf sheath in wheat (Triticum aestivum L.) and oat (Avena sativa L.) among different genotypes and agronomic practices (including planting densities and nitrogen application rates). The main objective was to quantify the mechanical role of the leaf sheath in oat and wheat crops by a “safety factor” method. On average, the leaf sheath contributed 40%, 68% and 38% of the overall stem bending strength, flexural rigidity and safety factor, in oat, while it accounted for 11%, 24% and 10%, respectively, in wheat plants. The significant contribution of the leaf sheath is due to its vital role in enlarging the peripheral position (i.e., second moment of area) and stiffness (i.e., Young's modulus). The contribution ratios (%) were found to be higher in oat than in wheat plants, due to the greater mass density of leaf sheath and more proficient/prevailing stay-green capability in oat genotypes. This study emphasizes the important mechanical role of clasping leaf sheath on stem internodes of cereals and indicates that the stay-green trait of the leaf sheath can be exploited to design appropriate varieties with improved lodging resistance and great yield potential.     

云南小麦品种（系）锈病和赤霉病抗性功能基因的KASP标记检测

利用5个锈病成株期抗性基因的KASP标记Sr2_ger9 3p、Lr34jagger、CSTM4_67G、Lr68-2、VPM_SNP和抗赤霉病基因Fhb1的KASP标记TaHRC-KASP,对云南省育成的42个小麦品种（系）进行检测,旨在筛选出含有目标基因的优异小麦种质,为云南省持久抗病小麦新品种（系）的选育提供材料。结果表明,4个材料含兼抗型成株抗锈病基因Lr34/Yr18/Sr57,频率为9.52%;6个品种（系）含兼抗型成株抗锈病基因Lr67/Yr46/Sr55,频率为14.29%;7个材料含抗慢叶锈病基因Lr68,频率为16.67%;含兼抗型成株抗锈病基因Sr2/Yr30和成株抗叶锈基因Lr37的材料各有1个,频率均为2.38%;未检测出含抗赤霉病基因Fhb1的品种（系）。云麦69、云麦75、云麦56、宜麦1号和宜麦3号等兼有2个成株期抗锈病基因,可作为今后云南持久抗锈病育种的抗源材料。     

轻钢结构抗震节能体系在“塞上农民新居”中的应用

针对宁夏地区农民传统住宅抗震性差，建筑外围护结构保温性能差，采暖系统能源消耗量大，环境污染严重等问题，提出采用轻钢结构配以轻质保温板材的轻钢结构抗震节能体系，以期为宁夏农村住宅设计提供指导性建议。     

浅析测定植物抗旱性方法的应用

本文介绍了干旱对植物伤害及表现,根据国内外相关文献资料对叶绿素荧光法和电阻抗图谱法两种测定植物抗旱性方法进行概述。     

Short time effects of biological and inter-row subsoiling on yield of potatoes grown on a loamy sand,and on soil penetration resistance,root growth and nitrogen uptake

Soil compaction, especially subsoil compaction, in agricultural fields has increased due to widespread use of heavy machines and intensification of vehicular traffic. Subsoil compaction changes the relative distribution of roots between soil layers and may restrict root development to the upper part of the soil profile, limiting water and mineral availability. This study investigated the direct effects of inter-row subsoiling, biological subsoiling and a combination of these two methods on soil penetration resistance, root length density, nitrogen uptake and yield. In field experiments with potatoes in 2013 and 2014, inter-row subsoiling (subsoiler) and biological subsoiling (preceding crops) were studied as two potential methods to reduce soil penetration resistance. Inter-row subsoiling was carried out post planting and the preceding crops were established one year, or in one case two years, prior to planting. Soil resistance was determined with a penetrometer three weeks after the potatoes were planted and root length density was measured after soil core sampling 2 months after emergence. Nitrogen uptake was determined in haulm (at haulm killing) and tubers (at harvest). Inter-row subsoiling had the greatest effect on soil penetration resistance, whereas biological subsoiling showed no effects. Root length density (RDL) in the combined treatment was higher than in the separate inter-row and biological subsoiling treatments and the control, whereas for the separate inter-row and biological subsoiling treatments, RLD was higher than in the control. Nitrogen uptake increased with inter-row subsoiling and was significantly higher than in the biological subsoiling and control treatments. However, in these experiments with a good supply of nutrients and water, no yield differences between any treatments were observed.     

贵州省三穗县鸭疫里默氏杆菌的分离鉴定、毒力基因检测及耐药性分析

为了解贵州省三穗县鸭疫里默氏杆菌（Riemerella anatipestifer，RA）的流行血清型、毒力和耐药情况，本试验从贵州省三穗县6个规模养鸭场临床疑似RA感染的病鸭体内分离出6株分离菌，对病原菌进行分离鉴定、毒力基因检测和耐药性分析。细菌分离鉴定结果显示，分离菌在巧克力琼脂培养基上长出表面光滑、圆形半透明的滴状菌落；革兰氏染色呈阴性短小杆菌，瑞氏染色呈两极浓染；分离菌均不具运动性，尿素、触酶和氧化酶试验均为阳性，符合RA生化特性，将6株分离菌分别命名为SS-RA1~SS-RA6；6株分离菌的16S rRNA基因序列与NCBI上RA参考菌株的基因序列相似性≥98%，说明6株分离菌均是RA；SS-RA1~SS-RA4为血清2型且含有8种毒力基因（OmpA、CAMP、wza、AS87_04050、Fur、SIP、TbdR1和luxE基因），SS-RA5和SS-RA6为血清11型，缺失AS87_04050基因，仅含有上述其余7种毒力基因；动物回归试验结果显示，攻毒组雏鸭均全部死亡，对照组雏鸭未表现明显临床症状，表明6株分离菌对雏鸭均有致病力；药敏试验结果显示，6株分离菌仅对羧苄西林、哌拉西林、头孢他啶、头孢氨苄、头孢曲松、头孢拉定和头孢哌酮7种抗菌药物敏感，对其他13种抗菌药物均表现不同程度的耐药，对氨基糖苷类和大环内酯类抗菌药物的耐药率为100%。本试验成功分离得到6株RA，为贵州省三穗县鸭疫里默氏杆菌病的疫苗选择和药物防治提供理论依据。     

草类植物抗病机制研究进展

草类植物病害是限制草牧业生产和发展的主要因素之一。目前抗病品种的开发利用是目前防治病害最经济有效的方法，植物抗病机制的研究对开发抗病品种和构建生态环境友好型病害防治至关重要。植物受病原菌侵染时形成多种复杂的防御机制，本研究主要从植物组织结构抗性、生理生化抗性、抗性基因和抗性数量性状位点（QTLs）定位等分子机制方面综述草类植物抗病机制研究进展，并提出我国草类植物抗病机制研究中面临的主要问题与解决办法，以期为草类植物抗病育种提供理论依据。