塔里木河中下游退耕还林还草综合生态效益评价研究

以恢复生态学为理论指导,区域可持续发展为目的,根据塔里木河中下游退耕还林还草的现状,建立退耕还林还草综合生态效益的评价指标体系和评价模型,应用层次分析法(AHP)原理推测塔里木河中下游生态林、经济林、牧草等3种退耕还林还草类型的综合生态效益指数,并与农田生态系统进行了对比研究。研究结果表明生态林、经济林、牧草等退耕还林还草类型的生态效益均大于农田生态系统。其生态效益指数排序为:经济林>生态林>牧草>农田。这一研究结果将为塔里木河中下游退耕还林还草工程规划、布局等经营方式提供理论依据。     

Characterization of Lotus Stem (Nelumbo nucifera) Starches Purified From Three Lakes of India

Starch was isolated from lotus stem obtained from three lakes of Jammu and Kashmir, India, and their physicochemical, morphological, and pasting properties were studied. Protein, fat, and amylose content varied significantly (p ≤ 0.05) among the different starches, but no significant difference was found in ash content. Amylose content was highest in lotus stem starch from Manasbal (30.0%), followed by the Dal (28.3%), and the Wular (25.0%). Functional properties like swelling, solubility, and water absorption showed an increasing trend with an increase in temperature from 50–90°C. Scanning electron microscopy of lotus stem starches showed small rounded and typical oval shaped granules with a smooth surface. The starch extracted from Wular and Dal lotus stems had larger granules than Manasbal starch. All the starches obtained from the three sources gave a similar B-type X-ray diffraction pattern. Pasting properties—such as pasting temperature, peak viscosity, breakdown, setback, and final viscosity—significantly differed among starches.     

Development and standardization of a monoclonal antibody-based rapid flow-through immunoassay for the detection of Aphanomyces invadans in the field

A monoclonal antibody-based flow-through immunoassay (FTA) was developed using a nitrocellulose membrane placed on the top of adsorbent pads enclosed in a plastic cassette with a test zone at the center. The FTA could be completed within 10 min. Clear purple dots against a white background indicated the presence of Aphanomyces (A.) invadans. The FTA limit of detection was 7 µg/mL for A. invadans compared to 56 µg/mL for the immunodot. FTA and polymerase chain reaction (PCR) could detect A. invadans in fish tissue homogenates at a 10^-11 dilution compared to a 10^-8 dilution by immunodot. In fish suffering from natural cases of epizootic ulcerative syndrome (EUS) collected from Mangalore, India, FTA and PCR could detect A. invadans in 100% of the samples compared to 89.04% detected by immunodot. FTA reagents were stable and produced expected results for 4 months when stored at 4~8℃. This rapid test could serve as simple and cost-effective on-site screening tool to detect A. invadans in fish from EUS outbreak areas and in ports during the shipment of live or frozen fish.     

2005—2017年全国3种主要蚊媒传染病发病数的圆形分布分析

为探讨圆形分布法在分析我国流行性乙型脑炎(乙脑)、登革热及疟疾等3种蚊媒传染病季节特征方面应用的可行性,本研究采用圆形分布法对2005年至2017年间全国的乙型脑炎、登革热、疟疾的发病情况进行了整理分析,并用自回归移动平均模型(ARIMA)验证。圆形分布法分析结果表明,乙脑、登革热、疟疾的预测发病高峰日分别为8月15日、10月5日和8月26日,高峰时期分别为7月11日至9月20日、9月9日至11月1日和6月12日至11月8日,ARIMA模型得到类似结果。因此,圆形分布法简单实用,对3种蚊媒传播疾病的防控具有较强的实用价值,从而为完善我国传染病的监测和防治工作提供参考依据。     

Effect of plant growth-promoting bacteria and soil compaction on barley seedling growth, nutrient uptake, soil properties and rhizosphere microflora

Inoculants are of great importance in sustainable and/or organic agriculture. In the present study, plant growth of barley (Hordeum vulgare) has been studied in sterile soil inoculated with four plant growth-promoting bacteria and mineral fertilizers at three different soil bulk densities and in three harvests of plants. Three bacterial species were isolated from the rhizosphere of barley and wheat. These bacteria fixed N₂, dissolved P and significantly increased growth of barley seedlings. Available phosphate in soil was significantly increased by seed inoculation of Bacillus M-13 and Bacillus RC01. Total culturable bacteria, fungi and P-solubilizing bacteria count increased with time. Data suggest that seed inoculation of barley with Bacillus RC01, Bacillus RC02, Bacillus RC03 and Bacillus M-13 increased root weight by 16.7, 12.5, 8.9 and 12.5% as compared to the control (without bacteria inoculation and mineral fertilizers) and shoot weight by 34.7, 34.7, 28.6 and 32.7%, respectively. Bacterial inoculation gave increases of 20.3–25.7% over the control as compared with 18.9 and 35.1% total biomass weight increases by P and NP application. The concentration of N and P in soil was decreased by increasing soil compaction. In contrast to macronutrients, the concentration of Fe, Cu and Mn was lower in plants grown in the loosest soil. Soil compaction induced a limitation in root and shoot growth that was reflected by a decrease in the microbial population and activity. Our results show that bacterial population was stimulated by the decrease in soil bulk density. The results suggest that the N₂-fixing and P-solubilizing bacterial strains tested have a potential on plant growth activity of barley.     

Phosphorus Adsorption Isotherm: A Key Aspect for Effective Use and Environmentally Friendly Management of Phosphorus Fertilizers in Calcareous Soils

Crop response to the phosphorus (P) application is often erratic in most soil types in the world. In Algeria, there is no information on the P behavior in calcareous soils. The purposes of this work were to investigate the degree of P fixing capacity and to predict P fertilizer requirements of crops according to calcareous levels in the soil. Soil samples (at 0–30 cm depth) were collected and spiked with 0, 25 and 50% of lime (CaCO₃). Phosphate sorption curves were well fitted to the Freundlich equation. Results indicated that the calcareous level was predominantly controlled the P sorption indices [sorption capacity (a), and P sorption energy (n)] to affect the estimation of external d P requirement (EPR_0.2) and P fertilizer rates. The understanding of P sorption and desorption by soils and extrapolating the developed relationship between soil calcareous contents and P fertilizer rates would be quite promising and accurate approach for the economic and effective use of P fertilizers in calcareous soils of Algeria.     

枣实蝇触角感器的超微结构初步研究

应用扫描电镜技术,对枣实蝇触角感器的类型、分布数量以及雌雄间的差异进行了初步研究。结果表明,枣实蝇触角上共有5种感器类型：鬃形感器、毛形感器、锥形感器、腔锥形感器和棒状感器。触角各节的感器类型和分布差异较大,以毛形感器分布数量最多,在触角各节均有分布,成簇着生于触角上,主要位于触角鞭节上;鬃形感器常成簇分布于柄节和梗节基部,而下颚须上松散分布,是所有感器当中最长的;锥形感器仅簇生于鞭节上,有大小锥两类;腔锥形感器是一类具孔感觉锥,位于表皮凹陷中的感受器,形状似圆锥,多分布于鞭节,是所有感器中最小的;棒状感器形态似棒球仅生于鞭节基部,长度似微毛。雌虫和雄虫的感器类型,分布和数量基本一致。     

塔里木河下游绿洲演变及其原因分析

[目的]以典型干旱区塔里木河下游为例,研究古绿洲的兴盛,其衰落、废弃,以及天然绿洲向人工绿洲转化,缩小、后退,一些下游人工绿洲的废弃、迁移的原因,总结变迁规律,为今后绿洲更好地发展提供科学参考.[方法]基于野外考察、文献查阅、历史比较法,参考考古与统计资料,分析各环境要素、考古信息数据、考古资料.[结果]塔里木河下游地区天然绿洲的存在,为该地区人类的生存提供了最原始的栖息场所与生存条件;随着时间的推移,天然绿洲在不同程度上为人类所利用和改造,随着社会经济的发展和人类生产活动的影响形成了大规模的人工绿洲.下游绿洲生态系统的脆弱性,出现了一些生态环境问题,其中绿洲的稳定性是最为核心和关键的.绿洲的稳定性受自然因素和人类活动的影响.由于自然和人类因素的影响,塔里木河下游绿洲从兴盛、废弃古城、古绿洲到近代以天然绿洲向人工绿洲转化、缩小、后退.[结论]如果不平衡的发展大大超出了自然可承载的范围,会导致毁灭性的后果.研究对于今后开发自然环境较为脆弱的塔里木河流域地区,坚持可持续发展,有着重要的借鉴意义.     

Low-molecular weight organic acids improve plant availability of phosphorus in different textured calcareous soils

Understanding the role of organic acids on phosphorus (P) sorption capacity of soils is very important for its economic and friendly management. Combining P application with low-molecular weight organic acids could result in its higher plant availability for prolonged time. Therefore, citric and oxalic acid (at the rate of 1.0 mM kg^?1 soil) were evaluated for their effect on P sorption capacity and its plant availability in two different textured calcareous soils. Organic acids decreased P sorption capacity and organic carbon partition coefficient (K_oc) whereas increased Gibbs free energy (ΔG) of P. Organic-acid-treated soils required lesser quantity of P fertilizer to produce soil solution P concentration optimum for plant growth (external P requirement [EPR_0.2]), that is, 0.2 mg L^?1. Citric acid was efficient than oxalic acid in the above effects. P sorption parameters of Freundlich model were negatively correlated with lime potential and ΔG whereas had positive correlation (P < 0.05) with EPR_0.2 and K_oc. Incubation with oxalic acid increased available P in loamy sand and loam soil by 20% and 30%, respectively. Thus, organic acids could help reduce application rate of P fertilizer through lowering its adsorption in highly P-fixing soils without compromise on yield.     

塔里木河中下游退耕还林还草综合生态效益评价--以新疆生产建设兵团农二师33团为例

根据恢复生态学原理 ,采用层次分析法 (AHP) ,建立了塔里木河中下游退耕还林还草综合生态效益评价指标体系和数学模型。以新疆生产建设兵团农二师 33团为例 ,对生态林、经济林、牧草等退耕还林还草类型进行综合生态效益评价 ,与农田生态系统进行了对比研究。评价结果表明 :生态林、经济林、牧草地等退耕还林还草类型的生态效益指数均大于农田生态系统 ,其综合生态效益指数排列顺序为 ,经济林 >生态林 >牧草 >农田 (棉花 )。这一研究结果可为塔里木河中下游退耕还林还草生态工程建设提供参考