The effect of some environmental factors on potato tuber numbers

Summary Five experiments studied the effects of shading, temperature and stolon growth medium on stolon and tuber formation. The lowest numbers of stolons and tubers were produced at the higher and lower nodes. Numbers of primary stolons and tubers were relatively stable across nodes and treatments and variation in total numbers was largely due to changes in numbers of lateral and branch stolons. In the field, 70% shading reduced numbers of stolons and tubers by reducing lateral and branch stolons, while in hydroponics, 45% shading and temperatures at initiation had no effect on tuber numbers. In both environments later planting tended to reduce numbers of stolons and tubers. There were large effects of the physical environment, with compost producing three times as many tubers as dry vermiculite. The potential number of tubers may be determined by the number of stolons and the environmental conditions affecting stolon formation and development.     

Above- and below-ground interactions with agricultural management: Effects of soil microbial communities on barley and aphids

Recent research has shown that agricultural management affects microbial biomass and community composition. We investigated the functional implications of such effects in terms of barley biomass production and nutrient acquisition, and whether changes in barley nutrient status affected aphid fecundity. Soils were collected from conventional, ley and organic arable fields and used as inocula in a glasshouse experiment. We determined microbial biomass and community composition using PLFA. We investigated barley growth and nutrient responses to the different soil inoculums, and the impact of excluding arbuscular mycorrhizal fungi (AMF). Aphids were applied to plants within clip cages and numbers of offspring counted. Microbial biomass and community composition were unaffected by agricultural management. The microbial communities altered root and shoot biomass and nutrient allocation, but had no effect on grain yield. Exclusion of AMF significantly increased shoot biomass but reduced grain yield. Aphid fecundity was not significantly affected by the microbial community or shoot nitrogen. We conclude that agricultural intensification does not necessarily have negative consequences for above- and below-ground interactions, and microbial communities from conventionally managed soils may offer equal benefit to crop productivity and nutrition as those from organically managed soils.     

锥栗1年生播种苗的年生长规律

通过对锥栗1年生播种苗苗高、地径的年生长变化及其生物量组分的分配模式研究.结果表明,苗高、地径的生长规律符合S型生长曲线,可用Logistic方程来拟合.采用有序样本聚类分析法划分苗木的生长时期,把生长期划分为4个阶段,即出苗期(4月6日以前)、生长初期(4月6日～5月20日)、生长盛期(5月21日～9月2日)和生长后期(9月3日～12月1日).其中,生长盛期的生长量占年生长量的67.5%.利用回归分析,得出苗高、地径和地上部分生物量呈线性相关.并拟合了苗高、地径及主根生长之间的最优回归方程,来了解苗木各部分生长的相关关系.     

地源热泵U型管地下换热器的准三维模型

为了模拟地源热泵U型管地下换热器的运行工况，通过耦合不同方向的低维模型，在换热器进水口的边界处引入换热功率函数作为边界条件。求和平均管壁各点到区域中心的距离来计算线热源到区域中心的距离。从而建立一准三维传热模型，并运用有限体积法求解。模拟结果与试验结果的最大相对误差为3．48％。平均相对误差1．33％，精度满足工程要求。而且随着运行时间的推移，相对误差呈减小趋势。运用该模型模拟得到的U型管管内流体温度分布情况表明，钻孔深度为40m时，进水支管与出水支管的温升比为1．34；钻孔深度为80和120m时该比值分别为1．90和2．77，而出水支管的温升几乎相同：说明增加钻孔深度会加剧U型管2支管之间的热短路。     

盐胁迫对7种草本地被植物种子萌发的影响

以浓度为0.05、0.10、0.20、0.30、0.40、0.50、0.60 mol·L-1的NaCl溶液以及重蒸馏水(对照)处理7种地被植物的种子,通过观察盐胁迫对7种植物种子萌发的影响,以比较植物间耐盐性的高低。试验采用随机区组设计,3次重复,对调查结果进行方差分析。结果表明:综合分析盐胁迫条件下种子的发芽率、胚根长度、发芽速度以及耐盐指数,可以对植物的耐盐性做出客观的评价;参试7种植物耐盐性强弱的排列顺序为:二色补血草>德国补血草>银水苏>地被石竹>紫花苜蓿>白三叶>百里香。     

基于SPH法的植保机高花纹轮牵引性能研究

植保机存在水稻田土壤时行走困难,牵引性能差等问题,以植保机高花纹驱动轮为研究对象,基于SPH(光滑流体粒子动力学法)建立植保机驱动轮-土壤有限元模型,以植保机高花纹轮结构参数中花纹深度,花纹倾斜角及花纹宽度为三个因素,以挂钩牵引力和牵引效率为牵引性能指标,利用ANSYS显式动力学求解模块LS-DYNA对驱动轮在水稻田土间行走进行仿真分析,通过正交试验法分析各因素对驱动轮土壤间行走牵引性能的影响规律,经过多目标优化,花纹深度50 mm、花纹倾斜角为80°、花纹宽度121.87 mm时可以获得最优的牵引性能,较原始值挂钩牵引力提高249 N,牵引效率提高15.51%,该结果为后期的驱动轮结构设计优化提供参考。     

早熟马铃薯农田土壤水分动态和地膜水分效应

对宁南干旱山区早熟丰产马铃薯农田土壤水分的研究结果表明，马铃薯农田土壤水分动态变化可以分为三个活动时期，它与区域的降雨和分配有极强的相似性，土壤水分垂直变化规律可以分为速变层，缓变层和相对稳定层。并研究了各个间的水分的关系。早熟丰产马铃的耗水量约为３１２－３９４ｍｍ。     

西安市地热水开采现状及其环境问题

通过对西安地区地热井水位、地面沉降和地裂缝活动、地震活动等资料的分析得到：西安市区地面沉降和地裂缝活动与地下热水开采有一定的联系；西安地区地下热水的开采与西安及邻区的地震活动明显相关，造成西安及邻区的地震活动性显著增强，在空间分布上表现为地震由西安城郊向邻近地区的转移。     

地面遥感监测系统在水土保持监测中的应用初探

目前我国3S技术地理信息系统GIS（Geographic Information Systen）、遥感RS（Remots Sensing）、全球定位系统GPS（Global Posititon System）广泛应用地质、军事、交通、环境、林业等多种领域。如果地面遥感监系统能在水土保持监测中得到充分应用,将使部分监测工作自动化、数字化、高效化,使水土保持监测工作更加系统、完善。就地面遥感监测系统在水土流失动态监测、水土保持工程验收、效益评估、监督执法等方面的应用进行了初步探讨。     

草被地上和地下部分拦蓄径流和减少泥沙的效益分析

研究草被地上和地下部分拦蓄径流和减少泥沙效益对科学评价草被防止土壤侵蚀的作用有重要科学意义。采用模拟降雨试验，分析了草被地上和地下部分拦蓄径流和减少泥沙的效益。结果表明，草被与森林植被一样，能有效防止土壤侵蚀。当草地地面覆盖达90％时，草被拦蓄径流效益达90％以上，而基本上无侵蚀发生。草被地上部分（茎枝＋枯落物）拦蓄径流效益为23．7％，其中茎枝部分拦蓄径流效益为9．0％和枯落物层拦蓄径流效益为14．7％，减少泥沙效益为44．6％；草被地下部分土壤体拦蓄径流效益为72．7％，拦蓄泥沙效益为55．4％。