DROUGHT STRESS: Soil Water Availability Alters the Inter‐ and Intra‐Cultivar Competition of Three Spring Wheat Cultivars Bred in Different Eras

Competition for water generates a classic aspect of the tragedy of the commons, the ‘race for fish’, where crops must allocate more resource to acquisition of the limiting resource than is optimal for crop yield allocation. A pot experiment using a simple additive (target–neighbour) design was conducted to examine the above‐ground and below‐ground growth of three spring wheat (Triticum aestivum L.) cultivars when grown alone and in mixtures at three levels of water availability. The effects of competition and water availability were compared by observing patterns of growth, biomass allocation and below‐ground outcomes. Competitive interactions were investigated among cultivars ‘HST’, ‘GY602’ and ‘LC8275’, target plant of each cultivar grown without neighbouring plants are referred to herein as control plant and one target plant of each cultivar sown surrounded either by same or another cultivar as intra‐ or inter‐cultivar competition. Competitive ability was assessed as the response ratio (lnRR) between the target plant surrounded by six other plants and the target plant in isolation. Our results showed that the cultivar ‘HST’, released over a century ago, produced a higher biomass and grain yield than the more recently released cultivars ‘LC8275’ and ‘GY602’ when grown as isolated plants with sufficient water supply. However, competition for resources from neighbours led to target plant biomass and grain yield being significantly reduced relative to controls in all three cultivars, particularly in ‘HST’. When subjected to intra‐cultivar competition, the two recently released cultivars ‘LC8275’ and ‘GY602’ had higher grain yields and water use efficiency for grain than ‘HST’ in all three water regimes. The landrace ‘HST’ had better and significantly linear relationships between biomass and biomass allocation, root length and specific root length, whereas the recent and modern cultivars had much more water‐related species‐specific changes in root morphology and allocation patterns. These results suggest that crop traits that influence competitive ability, such as biomass allocation to roots and root plasticity in response to drought have changed in modern wheat cultivars because of breeding and selection.     

城市化与“三农”问题及云南的路径选择

通过阐述城市化和"三农"问题的特点以及城市化对"三农"的影响进行分析探讨,并结合云南"三农"发展现状提出了云南城市化是解决"三农"问题的重要途径,提出了建设五级核心城市带动辐射周边的城市化发展思路和重点加大农村小城镇建设对促进云南农业、农村、农民发展的建议。     

黑龙江龙口自然保护区黑熊春季生境选择

分别于2008年4～5月和2009年4～5月,在龙口自然保护区对黑熊春季生境选择进行了研究,野外工作共设置87个10 m×10 m样方,并调查12个生态因子,其中利用样方41个,对照样方46个。通过Vanderploeg ＆Scavia选择指数得到,黑熊喜爱选择处于高海拔（〉450 m）、上坡位有石砬子且草本盖度适中（10%～40%）的生境,倾向选择乔木密度高（〉10株/100 m2）、郁闭度大（〉40%）、灌木密度较低（〈10%）、隐蔽级低（〈30%）、倒木密度大（〉1根/100 m2）、陡坡（〉30°）且向阳的针阔混交林。主成分分析与资源选择函数分析共同得到海拔、坡度、坡位、植被类型对黑熊生境选择影响较大,坡向和倒木密度影响较小的结果。综合分析,将Vanderploeg ＆ Scavia选择指数、主成分分析与资源选择函数相结合可以更好地反映黑熊生境选择情况。     

数字存储示波器特性及其应用

数字存储示波器是采用数字电路进行模/数转换，并通过存储器实现对触发前信号的记忆功能的一种具备存储功能新型示波器；此文尝试在分析数字存储示波器的原理和特性的基础上，对其在工程应用中应注意的问题进行分析。     

成都港两侧秋季鸟类资源调查

2013年9月至2013年11月,采用样线法对乐山市五通桥区冠英镇和牛华镇的鸟类资源进行了调查.共记录到冠英镇鸟类28种,隶属5目17科.牛华镇共记录到鸟类35种,隶属6目19科.多样性分析表明,冠英镇农田生境多样性指数最高（2.645）,牛华镇水域生境均匀度指数最高（0.949）,2个镇的水域生境之间的相似性最低（0.476）.冠英镇水域生境鸟类群落不稳定,对岷江河应采取一定的保护措施.     

蒸汽采暖系统中减压阀的选型与安装

介绍了各类减压阀的特点并进行了比较,论述目前蒸汽系统中减压阀选型的三种方法,并根据实践经验总结了减压阀的安装要点。     

联苯菊酯10%水乳剂的配方研究

本研究通过正交优化得到联苯菊酯10%水乳剂的最佳配方：联苯菊酯原药10%,二甲苯20%,农乳602#3.5%,Tween-20 2.5%,农乳500#2%,乙二醇4%,有机硅消泡剂0.2%,去离子水补足至100%。最佳生产工艺为：使用高速剪切机,剪切转速6 000r/min,剪切时间4min。该水乳剂pH值5.7～6.5,稀释100倍于（30±2）℃恒温水浴24h未出现浮油、沉油、沉淀,经（54±2）℃热贮14d,分解率〈2%,制剂表面张力低,倾倒性佳。     

居住小区绿化施工及绿化植物选择原则

综述了居住小区绿化的施工原则、绿化植物选择原则等,以期为居住小区的绿化提供参考。     

柽柳有效天敌昆虫筛选标准的建立

参照前人对杂草天敌筛选标准、植物与昆虫互作理论和近年来对柽柳原产地主要天敌生物学特性的研究结果，制定出柽柳天敌遴选量化标准，共计10项特征，满分为47分。并以此对取食柽柳的12种天敌进行了筛选。柽柳条叶甲得分最高（43分），其次是斯氏伞锥象（41分），推荐这2种天敌昆虫作为首选天敌引入美国做进一步评价。     

Quantifying patch distribution at multiple spatial scales: Applications to wildlife-habitat models

Multiscale analyses are widely employed for wildlife-habitat studies. In most cases, however, each scale is considered discrete and little emphasis is placed on incorporating or measuring the responses of wildlife to resources across multiple scales. We modeled the responses of three Arctic wildlife species to vegetative resources distributed at two spatial scales: patches and collections of patches aggregated across a regional area. We defined a patch as a single or homogeneous collection of pixels representing 1 of 10 unique vegetation types. We employed a spatial pattern technique, three-term local quadrat variance, to quantify the distribution of patches at a larger regional scale. We used the distance at which the variance for each of 10 vegetation types peaked to define a moving window for calculating the density of patches. When measures of vegetation patch and density were applied to resource selection functions, the most parsimonious models for wolves and grizzly bears included covariates recorded at both scales. Seasonal resource selection by caribou was best described using a model consisting of only regional scale covariates. Our results suggest that for some species and environments simple patch-scale models may not capture the full range of spatial variation in resources to which wildlife may respond. For mobile animals that range across heterogeneous areas we recommend selection models that integrate resources occurring at a number of spatial scales. Patch density is a simple technique for representing such higher-order spatial patterns.