Man-made desert algal crusts as affected by environmental factors in Inner Mongolia, China

Man-made desert algal crusts were constructed on a large scale (3000m(2)) in Inner Mongolia, China. Microcoleus vaginatus was mass cultivated and inoculated directly onto unconsolidated sand dune and irrigated by automatic sprinkling micro-irrigation facilities. The crusts were formed in a short time and could resist the erosion of winds and rainfalls 22 days after inoculation. The maximum biomass in the man-made algal crusts could also reach 35 mu g Chl a/cm(2) of soil. Effects of environmental factors such as temperature, irrigation, rainfall and soil nutrients on algal biomass of man-made algal crusts were also studied. It was found that rainfalls and lower light intensity had significantly positive effects on the biomass of man-made algal crusts. The preliminary results suggested that man-made algal crusts could be formed rapidly, and thus it might be a new feasible alternative method for fixing unconsolidated sand. (c) 2006 Elsevier Ltd. All rights reserved.

支持EJB动态分布的组件迁移模型与算法

Web应用服务器是Web计算环境下的新型中间件，为基于组件的分布式Web应用提供了基础运行平台．组件静态分布限制了事务性Web应用在运行期间适应执行环境变化的能力．为了满足Web应用的动态分布需求，Web应用服务器需在底层为组件提供一种动态迁移的能力．如何维持组件迁移前后的一致性是组件迁移中最棘手的问题之一．为解决此问题，定义了组件迁移一致性约束CMC(component migration constrains)，并给出了在 J2EE(Java 2 platform enterprise edition)应用服务器中支持EJB(enterprise Java Bean)动态分布的组件迁移模型和 sLB_Copy,SFB_Copy,EB-Copy 3个迁移算法．分析得出sLB_Copy,SFB_copy和EB_copy均满足CMC约束．迁移模型和算法已在自主研制的Web应用服务器WebFrame2．0中实现，并已应用到自适应负载平衡、失效恢复等多个方面．

陕北黄土丘陵沟壑区水土保持耕作及施肥下农田土壤种子库特征

为了探明多年免耕下农田恶性杂草发生的机理,提高保护性耕作下作物对农田恶性杂草持久稳定的抑制效果,依据陕西安塞田间4a的定位试验,采用小区调查取样和室内实验相结合的方法,从物种组成、密度特征、多样性以及相似性特征等方面,研究了黄土丘陵旱作农区大豆(Glycine max)、玉米(Zea mays)、红小豆(Semen Phaseoli)、马铃薯(Solanum tuberosum)在翻耕化肥(CF)、翻耕有机肥(CM)、翻耕无肥(CN)、免耕化肥(NF)、免耕有机肥(NM)、免耕无肥(NN)等水平下的农田土壤种子库。结果表明:(1)4种作物24种土样中共萌发出12个物种1965株幼苗,隶属于7科12属。1年生杂草占94%,棒头草(fugax nees ex steud)、苋菜(Acalypha australis)、马唐(Digitaria sanguinalis)、早熟禾(Poasphondylodes)为优势种,占87%。(2)在0～20cm土层不同处理间,土壤种子库的密度变动于(282.9±63.4)～(7482.5±1078.3)粒.m-2,其中,红小豆小区>马铃薯小区>大豆小区>玉米小区;翻耕小区>免...

桃树茎直径微变化与土壤水势及气象因子的关系

通过对充分供水和逐步干旱处理的盆栽"仕女红"桃树茎直径微变化动态的观测,分析了茎直径日最大收缩量(MDS)、日增长量(DI)和日最大值恢复时间(RT)对水分状况和气象因子的响应,并对适宜灌溉控制指标进行了探讨。结果表明:随土壤水势降低,桃树茎直径MDS和RT呈增大趋势,DI呈下降趋势并由正值变为负值;气象因子对桃树茎直径变化影响显著,太阳辐射(Rn)和空气相对湿度(RH)对MDS影响最强烈,连续降雨对DI和RT影响显著。DI受土壤水势影响产生变化的趋势明显并受气象因子影响较小,是最理想的灌溉控制指标,可将DI=0作为灌溉控制临界值;MDS受气象因子影响强烈,变异性较大,且需要充分灌溉条件下的MDS作为参考,RT与土壤水势的相关性不高,因此均不适合单独作为灌溉控制指标。

不同前茬对设施黄瓜产量和品质及土壤酶活性的影响

试验研究了在延安日光温室不同前茬作物条件下,黄瓜随着生长季节的变化其产量和品质及土壤呼吸和酶活性的动态变化。结果表明,前茬为豇豆的黄瓜产量和土壤碱性磷酸酶活性较高,前茬为番茄的黄瓜可溶性糖含量和土壤呼吸强度较高,前茬为四季豆的黄瓜维生素C含量较高,前茬为翻青玉米的黄瓜硝酸盐含量和土壤脲酶活性较高,前茬为翻青黑豆的土壤蔗糖酶活性较高。从提高黄瓜产量的角度出发,豇豆-黄瓜是最佳模式,而从改善黄瓜品质的角度出发,番茄-黄瓜和四季豆-黄瓜是最优模式

干旱对不同冬小麦旗叶光合产物供应能力的影响

研究干旱对小麦旗叶光合产物供应能力的影响,揭示小麦抗旱高产的生理机制,为提高小麦的抗旱能力及高产稳产提供理论依据。【方法】在防雨池栽培条件下,以旱地冬小麦品种长武134(抗旱性强)和水地冬小麦品种陕253(抗旱性弱)为试材,以适宜水分处理为对照(CK,土壤含水量为田间持水量的70%～75%),研究干旱处理(土壤含水量为田间持水量的50%～55%)对不同冬小麦旗叶光合产物供应速率(净光合速率和蔗糖合成能力)和供应持续期的影响。【结果】与对照相比,干旱处理降低了冬小麦灌浆中后期旗叶净光合速率,缩短了净光合速率高值持续期(PAD),其中长武134降幅较小,净光合速率较高;干旱处理提高了冬小麦灌浆初期旗叶的蔗糖磷酸合成酶(SPS)活性,其中长武134增幅较大,且在灌浆中后期依然能保持相对较高的蔗糖供应能力;干旱处理缩短了冬小麦叶绿素含量缓降期(RSP),提高了丙二醛(MDA)含量,加速了旗叶的衰老,缩短了光合产物的供应持续期,其中长武134受干旱影响较小;干旱处理降低了冬小麦灌浆中后期主茎穗粒质量积累量及其速率,其中长武134降幅较小。【结论】干旱条件下,抗旱品种长武134旗叶在灌浆中后期可维持较高的光合产物...

A study on GaP/Si heterostructures grown by GS-MBE

GaP/Si is a promoting heterostructure for Si-based optoelectronic devices since lattice constants of GaP and Si are so closed that they can match with each other. GaP was successfully grow on (100) Si subtracts by Gas-Source Molecular Bean Epitaxy (GS-MBE) in the study. The GaP/Si heterostructure was characterized by X-ray double crystal diffraction, Anger electron spectrograph, X-ray photonic spectrograph and photoluminescence (PL) measurements. The results showed that the epitaxial GaP layers are single crystalline, in which a parallel to and a (perpendicular to)are 0.54322 and 0.54625 nm, respectively. The peaks in PL spectra of GaP epitaxial layer grown on Si are 650, 627 and 640 nm, respectively. The study demonstrated that GaP/Si is a kind of lattice matched heterostructures and will be a promoting materials for future integrated photonics.

花椒叶和土壤浸提液对土壤微生物、土壤酶及土壤化学性质的影响

花椒（Zanthoxylum bungeanum Maxim.）是川西地区重要的经济植物，化感作用是花椒连作障碍的原因之一，而花椒凋落物和根系分泌物对土壤质量的影响是花椒化感作用的一个重要方面。系统研究花椒如何影响土壤有助于深入理解和解决花椒连作障碍。本文主要以大红袍（10a生）花椒叶和种植过花椒的土壤的浸提液浇灌花椒幼苗进行试验，分析叶浸提液与土壤浸提液对非花椒生长土壤中土壤微生物、土壤酶及土壤化学性质的影响。主要结果如下： 1.花椒叶浸提液和土壤浸提液减少了土壤中微生物的种类、组成和数量。本试验中未施加浸提液的土样中根际微生物明显高于非根际区，在经过花椒叶浸提液处理后，根际细菌、真菌和放线菌数量以及微生物总数都有所减少，这样将会导致土壤中的有效养分的供给减少，进而可能影响植物的生长。 2．施加花椒叶浸提液和土壤浸提液，以及花椒幼苗的栽种，对不同土样中的土壤酶各有促进和抑制作用。在浸提液处理下，水解酶之间及氧化还原酶之间各存在相互促进作用。 3.施加花椒叶浸提液和土壤浸提液均抑制了根际土中全氮和有机质含量，叶浸提液还抑制了无苗土中全磷含量，土壤浸提液还抑制了无苗土中全氮含量与根际土全磷、有机质含量。但两种浸提液均促进了根际土中有效磷和水解性氮含量、根外土中全磷含量，叶浸提液促进了根际土中全磷含量，土壤浸提液促进了根外土中有效磷含量。全氮和有机质含量的下降可能对植物生长发育不利。 4．土壤化学性质与土壤酶活性在不同土样中有不同的相关性。全氮含量在施加叶浸提液的土样中与蛋白酶活性呈正相关。水解性氮含量在施加叶浸提液的土样中与蛋白酶活性、蔗糖酶活性呈正相关。全磷含量在施加叶浸提液的土样中与多酚氧化酶活性呈正相关；在施加土壤浸提液的土样中与蛋白酶活性、蔗糖酶活性呈正相关，与多酚氧化酶活性呈负相关。有效磷含量在施加叶浸提液的土样中与多酚氧化酶活性呈正相关，与蛋白酶活性呈负相关；在施加土壤浸提液的土样中与蛋白酶活性、过氧化氢酶活性呈正相关。有机质含量在施加叶浸提液的土样中与蛋白酶活性、蔗糖酶活性呈正相关。 Zanthoxylum bungeanum is one of the most important cash crops in Eastern Tibetan Plateau. Allelopathic effects could be one of reasons for Z. bungeanum’s continuous cropping impediment. The effects of secretion of leaf and root of Z. bungeanum on soil quality is a important way of Z. bungeanum’s allelopathic effects. However, allelopathic effect of Z.bungeanum on soil microbes, enzyme activities and chemical property were seldom studied. In this study, leaf and soil extracts of Da Hongpao(DHP), the most common varieties of Z.bungeanum in this area, were used to assess allelopathic effect of Z. bungeanum on soil biology and biochemistry by pot experiments . The main results showed that: 1. The irrigation of two kinds of extracts reduced the species, component and quantity of soil microbes. In rhizosphere soil which irrigated by distilled water, the quantity of soil microbes is significantly different from exoroot soil. In rhizosphere soil which irrigated by leaf extracts, the quantity of bacterial, fungi, actionmycete and gross of microbes were decreased, it may resulted in reduce of Available nutrient in soil, and influenced the growth of plants. 2．The irrigation of two kind of extracts reduced or enhanced the enzyme activities in different soils. Interaction between hydrolytic ferments and redoxases were promoted each other. 3. The irrigation of two kinds of extracts reduced the total N and organic matter in rhizosphere soil. Leaf extracts also reduced the total P in soil without seedling. Soil extracts reduced total N in soil without seedling and total P, organic matter in rhizosphere soil. But both extracts also enhanced available P and hydrolysable N in rhizosphere soil, total P in exoroot soil. Leaf extracts enhanced total P in rhizosphere soil. Soil extracts enhanced available P in exoroot soil. The reduction of total N and organic matter may influence growth of plants. 4．Positive correlations between total N and prolease, hydrolysable N and prolease, hydrolysable N and saccharase, total P and polyphenol oxidase, available P and polyphenoloxidase, organic matter and prolease, organic matter and saccharase, were studied in soil irrigated by leaf extracts. In soil irrigated by soil extracts, there are positive correlations between total P and prolease, total P and saccharase, available P and prolease, available P and catalase, while negative correlation between total P and polyphenoloxidase, available P and prolease, available P and catalase was found.

不同植被对土壤侵蚀及铜元素流失的影响

通过野外天然降雨产流及人工模拟降雨试验,研究不同植被对坡面土壤侵蚀及土壤铜元素流失的影响及降雨过程中铜元素的流失规律。结果表明:(1)紫花苜蓿、绿豆、荒草3种植被覆盖小区的年径流量为5183.8,5 366.2,3 867.3 m~3/km~2,比裸地减少33%,30.8%和50.1%;侵蚀模数为379.18.482.3,15.78 t/km~2,比裸地减少34.7%,16.4%和97.2%;全年全铜流失量为12.9,25.5,0.46 kg/km~2,有效铜流失量为6.22,11.01,0.15 kg/ km~2,分别比裸地减少67.3%,35.3%,98.8%和54.6%,19.6%,98.9%;(2)在模拟降雨过程中,农地小区的产流产沙强度过程呈现波动上升趋势,产沙过程波动较产流过程剧烈。铜元素流失强度过程与产流产沙强度过程相似,但其峰值多于产流产沙过程,且最高峰出现时间不同。有效铜流失强度变化率略高于全铜。

不同水肥条件对马铃薯肥料N利用率的影响

在旱棚控制条件下 ,用五因素五水平二次回归正交旋转组合设计 ,研究了水肥施用分配 ,补水量 ,施N量 ,施K量 ,有机肥施用量的综合作用效应 .结果表明 ,五因素对肥料N利用率的作用顺序为施N量 >补水量>水肥施用分配 >有机肥施用量 >施K量 .水肥施用分配相对于不同水、化肥 (N、K )、有机肥量的选择 ,可以大大地提高肥料N利用率 ;量少应重前施用 ,量多重后施或均施为好 .补水量与施N量的耦合规律为 :高水高肥效果最佳 ,肥料N利用率可达 5 7 83 % ,中水中N及低水低N次之 ,为 2 9 17%～ 40 99% ;高水低N或低水高N导致最低的利用率 ,为 2 2 87%或 2 2 5 1%

论窖灌农业中水窖的配置模式与窖水高效利用技术

针对黄土高原蓬勃发展的窖灌农业 ,提出3种水窖配置模式 :峁顶光头式 ;路旁葡萄串式和场、院、凹地单点式。为了高效利用水窖集蓄的雨水资源 ,文中推荐自压微灌、外动力加压微灌、坑灌和水肥穴灌等4种窖水高效利用技术。

对渭北地区集雨灌溉的思考——以富平县底店乡“窖灌农业”示范区为例

合理高效地利用雨水资源对西北干旱半干旱地区尤其是地表水缺乏地下水不易利用地区的经济发展具有十分重要的意义。基于此 ,我们在陕西省“窖灌农业”试验示范基地对蓄水设施的修筑、运行、维护及水质、雨水利用现状等进行了调研和考察 ,指出了其存在的问题、解决措施及进一步发展的思路 ,为该地及整个渭北地区雨水集流灌溉的进一步发展提供指导和参考

黄土高原沟壑区沟坡地苹果优质丰产栽培技术体系

确立了黄土高原沟壑区沟坡地为优质苹果生产地带 ,建立起沟坡道路防蚀体系 ,春栽改秋栽 ,量化施肥、灌水、修剪 ,生态防治病虫害 ,加强优果生产和采后处理等是黄土高原沟壑区沟坡地带优质苹果生产的主要技术措施。

秸秆还田对灌溉玉米田土壤反硝化及N_2O排放的影响

运用乙炔抑制技术研究了不同施氮水平下秸秆还田对灌溉玉米田土壤反硝化反应和氧化亚氮(N2O)排放的影响。结果表明,土壤反硝化速率及N2O的排放受氮肥施用、秸秆处理方式及其交互作用的显著影响。与秸秆燃烧相比,不施氮或低施氮水平时,秸秆还田可刺激培养初期反硝化反应速率及N2O排放,增加培养期间N2O平均排放通量;高施氮水平时,秸秆还田可降低反硝化反应速率及反硝化过程中的N2O排放。秸秆还田可降低反硝化中N2O/N2的比例。

Emergy Assessment of a Wheat-Maize Rotation System with Different Water Assignments in the North China Plain

Sustainable water use is seriously compromised in the North China Plain (NCP) due to the huge water requirements of agriculture, the largest use of water resources. An integrated approach which combines the ecosystem model with emergy analysis is presented to determine the optimum quantity of irrigation for sustainable development in irrigated cropping systems. Since the traditional emergy method pays little attention to the dynamic interaction among components of the ecological system and dynamic emergy accounting is in its infancy, it is hard to evaluate the cropping system in hypothetical situations or in response to specific changes. In order to solve this problem, an ecosystem model (Vegetation Interface Processes (VIP) model) is introduced for emergy analysis to describe the production processes. Some raw data, collected by investigating or observing in conventional emergy analysis, may be calculated by the VIP model in the new approach. To demonstrate the advantage of this new approach, we use it to assess the wheat-maize rotation cropping system at different irrigation levels and derive the optimum quantity of irrigation according to the index of ecosystem sustainable development in NCP. The results show, the optimum quantity of irrigation in this region should be 240-330 mm per year in the wheat system and no irrigation in the maize system, because with this quantity of irrigation the rotation crop system reveals: best efficiency in energy transformation (transformity = 6.05E + 4 sej/J); highest sustainability (renewability = 25%); lowest environmental impact (environmental loading ratio = 3.5) and the greatest sustainability index (Emergy Sustainability Index = 0.47) compared with the system in other irrigation amounts. This study demonstrates that application of the new approach is broader than the conventional emergy analysis and the new approach is helpful in optimizing resources allocation, resource-savings and maintaining agricultural sustainability.