Performance of DSSAT-Nwheat across a wide range of current and future growing conditions

Crop models are widely used in agricultural impact studies. However, many studies have reported large uncertainties from single-model-based simulation analyses, suggesting the need for multi-model simulation capabilities. In this study, the APSIM-Nwheat model was integrated into the Decision Support System for Agro-technology (DSSAT), which already includes two wheat models, to create multi-model simulation capabilities for wheat cropping systems analysis. The new model in DSSAT (DSSAT-Nwheat) was evaluated using more than 1000 observations from field experiments of 65 treatments, which included a wide range of nitrogen fertilizer applications, water supply (irrigation and rainout shelter), planting dates, elevated atmospheric CO₂ concentrations, temperature variations, cultivars, and soil types in diverse climatic regions that represented the main wheat growing areas of the world.DSSAT-Nwheat reproduced the observed grain yields well with an overall root mean square deviation (RMSD) of 0.89 t/ha (13%). Nitrogen applications, water supply, and planting dates had large effects on observed biomass and grain yields, and the model reproduced these crop responses well. Crop total biomass and nitrogen uptake were reproduced well despite relatively poor simulations of observed leaf area measurements during the growing season. The low sensitivity of biomass simulations to poor simulations of leaf area index (LAI) were due to little changes in intercepted solar radiation at LAI >3 and water and nitrogen stress often limiting photosynthesis and growth rather than light interception at low LAI.The responses of DSSAT-Nwheat to temperature variations and elevated atmospheric CO₂ concentrations were close to observed responses. When compared with the two other DSSAT-wheat models (CERES and CROPSIM), these responses were similar, except for the responses to hot environments, due to different approaches in modeling heat stress effects.The comprehensive evaluation of the DSSAT-Nwheat model with field measurements, including a comparison with two other DSSAT-wheat models, created a multi-model simulation platform that allows the quantification of model uncertainties in wheat impact assessments.     

基于模糊数学的洲滩人工林复合经营模式多功能评价

在资料查询、专家咨询获取各种模式林分相关信息的基础上,选择华容县5种当地典型的杨树人工林复合经营模式,共设置20块样地,对相应指标进行实地调查,从生态效益、经济效益、社会效益三个方面筛选评价指标,构建了洲滩人工林复合经营的综合评价指标体系,运用层次分析法和模糊数学综合评判法对5种杨树人工林经营模式进行了评价。评价结果表明:5种杨树人工林复合经营模式的生态、经济、社会综合效益评价优劣排序为林-菜模式(0.631 3)林-菌模式(0.611 8)林-药模式(0.488 3)林-草模式(0.475 2)纯林模式(0.456 7)。无论从生态功能、经济功能、社会功能还是从综合效益来看,研究区人工林复合经营模式都优于纯林模式。     

基于非线性假设的农业机械化综合评价——以四川地区为例

农业机械化水平受到自然、经济、社会等多重因素影响,区域性特征非常明显,对农机化的评价维度和方法目前也未形成共识。为此,以四川省农机发展水平为例,确定四川省农业机械化评价维度后,基于几个维度的非线性关系假设,使用三维空间向量对该地区农业机械化水平进行了综合评价。     

基于模糊评判法的长安区滑坡崩塌灾害易发性分区评价

在对长安区滑坡崩塌地质灾害发育现状及形成条件分析的基础上,结合地质灾害易发性分区评价方法,采用模糊综合评判法对长安区滑坡崩塌地质灾害进行了易发性区划评价。结果表明,长安区滑坡崩塌易发性分区分为6个高易发区域、3个中易发区、1个低易发区(C)和1个不易发区(D),高易发区总面积为190.94 km2,中易发区为382.93 km2,低易发区为299.21 km2,不易发区为707.56km2。     

以发展创造教育为导向 改革部队教育评价体系

传统的教育评价体系一定程度上阻碍了创造教育的实施,因此探索与创造教育相适应的评价体系将成为时代之必须。本文基于部队院校评价现状,在学习借鉴当今世界最新的评价理念和总结已有研究成果的基础上,从评价机构和评价指标和评价法方面,提出与部队院校相适应的创造教育评价体系。     

2014年瓮安县花卉苗木基地建设规划

文章根据省、州、县有关文件指示,通过环境立地条件分析,规划了瓮安县发展花卉苗木基地布局及方案。     

山东农业科技期刊学术影响力分析与动态评估

利用动态评估模型对2008~2012年山东13种农业科技期刊的学术影响力进行分析。结果显示,2008~2012年中,13种农业类科技期刊的总被引频次和影响因子总体呈上升趋势,5年间,平均总被引频次增加了84.85%,平均影响因子增加了47.35%;平均学术影响力呈快速增长趋势,5年间增长了268%。各期刊发展不均衡,其中,《山东农业科学》和《中国烟草科学》学术影响力分别位居第一和第二,且发展态势良好。     

学科影响指标在期刊评价中的作用探讨

对学科影响指标反映期刊学术影响力的情况、与其他评价指标之间的联系、在期刊学科分类工作中的作用及其存在的局限性进行了初步分析和探讨。     

对教师个人多媒体教学平台的研究

多媒体教学技术被广泛地应用于教学,有效提高了课堂教学效率和教学质量。但过分或不当使用多媒体技术也会影响和制约着教学效果,限制教师主动性和禁锢教师临场发挥。有必要对这项技术在形式、手段和方法上进行一些反思,重新探讨教学中所需要的多媒体软硬件环境以及平台,研究适合高校教师使用的多媒体辅助教学平台及工具。