The response of foraging bumblebees to successional change in newly created arable field margins

Agricultural intensification is likely to have been a major factor leading to serious declines in bumblebee abundance and diversity in the UK and elsewhere over recent decades. Opportunities to restore habitat for bumblebees on uncropped arable field margins are now available, although the methods by which this restoration can be achieved have not been fully investigated. We present the results of a three year study undertaken to investigate the response of foraging bumblebees to five different arable field margin treatments (sown and unsown), as part of a replicated field experiment on arable farmland in northern England (UK). Bumblebee abundance was closely linked to successional changes in availability of suitable forage plant species. Field margin treatments sown with a `grass and wildflower' mixture had the highest bumblebee abundance, and provided a consistent supply of forage species, with different components of the seed mixture flowering in each year. The unsown natural regeneration treatment attracted foraging bumblebees in only the second year due to the local abundance of thistles, so we consider this option to be both inconsistent in terms of forage provision and agronomically unacceptable. Our results are discussed in terms of developing suitable measures to achieve the restoration of habitats for bumblebees on arable farmland.     

Long-term postsurgical outcomes of mast cell tumors resected with a margin proportional to the tumor diameter in 23 dogs

We evaluated the postsurgical outcomes of cutaneous or subcutaneous mast cell tumors (MCTs, n=25) in 23 dogs, resected with lateral surgical margins proportional to the widest tumor diameter, including at least one facial plane. The tumor diameter range was 0.3–2.6 cm (median: 0.9 cm), and all were histologically diagnosed as Kiupel’s low-grade MCT. Resection was histologically complete in 20, close (deep margin) in three, and incomplete (deep margin) in two. No dogs developed local recurrence at the site of initial surgery during follow-up of 161–2,219 days (median: 976 days). These results suggest that resection of low-grade, relatively small MCTs with surgical margins proportional to the tumor diameter is a practical procedure with high success rates.     

四川盆地西南缘山地核桃产业良种化发展现状及对策——以宁南县为例

对宁南县山地核桃产业发展现状进行分析,指出核桃产业良种化过程中存在的问题和不足,提出加快良种选育、推广自选本土良种、利用现有核桃园改建为良种采穗圃、加强良种嫁接管理技术培训等对策及建议,以促进核桃产业良种化发展。     

草莓温室施用百菌清对施药及采收人员的暴露水平与风险评估

采用手动背负式喷雾器,在草莓温室中均匀施用75%百菌清可湿性粉剂,通过贴片法分析了施药者及果实采收者的人体暴露量,研究了草莓温室施用百菌清对操作人员的职业暴露风险。结果表明:在草莓温室中施用百菌清,对施药者人体暴露的施药液量为19.2~46.6 mL/h,平均为30.2 mL/h,主要暴露部位为小腿;采收果实时,施药后第1天采收者人体暴露的施药液量为3.8 mL/h,第7天时为0.027 mL/h,主要暴露部位均为手部。在本研究暴露条件下,施药者的安全限值(MOS)为0.258,表明该暴露环境对施药者存在风险;施药后1~7 d,采收者的MOS值均1,表明该暴露环境对采收者人体暴露为安全。研究表明,在草莓温室中施用百菌清,对田间操作人员存在职业暴露风险,因此应注意加强防护措施,或缩短暴露时间;采收时,对采收者无职业暴露风险,但应对主要暴露部位手部加强防护。     

宝天曼三桠乌药对降雨减少后的生理生态响应

[目的]在宝天曼森林原位建立降水减少(截雨)样地后,样地内的三桠乌药出现了顶端枯死,本研究从水和碳的角度,探讨三桠乌药顶端枯死的原因。[方法]2013年4月在宝天曼锐齿栎林原位建立了3块截雨样地,在2014年生长季干旱时,采用压力室、低压液流系统和蒽酮硫酸法测定了三桠乌药的水力系统特征和非结构性碳等指标。[结果]显示:(1)三桠乌药在截雨处理后出现了顶端枯死;三桠乌药最大导管长度约为60 cm,栓塞50%时的水势(P50)为-1.43 MPa,其木质部栓塞脆弱性较大。在截雨处理1年后生长季较干旱时,净光合速率、凌晨水势、中午水势显著低于对照,中午栓塞显著高于对照,且水力安全边际为负值。(2)三桠乌药气孔导度、蒸腾速率、叶面积、导管直径、边材比导率、叶片比导率显著下降,Huber值、导管密度显著升高;而叶片、韧皮部、木质部3个器官的可溶性糖、淀粉、总非结构性碳与对照差异不显著。[结论]水力失衡是三桠乌药顶端枯死的主要原因,而蒸腾面积、水分输导系统等的变化表明三桠乌药在缺水环境下进行了一定的适应性调节,但这些调节不足以使三桠乌药在缺水情况下避免水力失衡而导致的顶端枯死。     

养殖密度对卵形鲳鲹离岸大型抗风浪网箱养殖效果的影响

在海南临高后水湾海域的抗风浪网箱养殖基地,采用60 m周长的高密度聚乙烯(HDPE)圆形双浮式抗风浪网箱,分别设置40,45,50,55,60尾·m~(-3)水体5个密度梯度养殖卵形鲳鲹,研究了养殖密度对大型网箱养殖卵形鲳鲹养殖效果的影响。结果表明,在40~50尾·m~(-3)密度范围内,养殖密度对成活率和利润率影响不明显(P0.05),成活率高达80%以上,利润率也达到了45%以上,而后,随密度增加均显著降低;饵料系数随密度增加而升高,最低40尾·m~(-3)组(1.72),最高60尾·m~(-3)组(1.93);商品鱼a级比率随密度增加而下降,b,c级则上升;单位成本在40~45尾·m~(-3)间随密度增加而下降(P0.05),之后呈现上升趋势(P0.01),最高为60尾·m~(-3)(18.08元·kg~(-1)),最低为45尾·m~(-3)(16.43元·kg~(-1));利润在40~50尾·m~(-3)间随密度增大而增加(P0.01),而在50~60尾·m~(-3)间随密度增大快速下降(P0.01),最高利润为50尾·m~(-3),高达185.49元·m~(-3),最低为60尾·m~(-3),仅123.85元·m~(-3)。因此,为了控制养殖风险,获得最好的经济效益,建议养殖密度控制在45~50尾·m~(-3)水体。     

Soil properties and herbaceous characteristics in an age sequence of Haloxylon ammodendron plantations in an oasis-desert ecotone of northwestern China

Haloxylon ammodendron,a typical desert shrub with C4 pathway of photosynthesis,possessing a strong ability to adapt to an extreme drought environment,has a rapid growth rate in sandy lands and is widely used in sand-fixing shelter-forest systems in oasis-desert ecotones.To assess the effects of H.ammodendron plantation on the soil,we measured soil properties and herbaceous characteristics along a nearly 40-year chronosequence after H.ammodendron was planted in shifting sand dunes in an oasis-desert ecotone.Results showed that silt and clay fractions increased significantly in the topsoil.The accumulation rates of soil organic carbon(SOC),total nitrogen(TN) and total phosphorus(TP) were faster in the early stages(0–9 years) and slower in the late stages(9–39 years).The soil p H and electrical conductivity(EC) were higher than those in the non-vegetation dunes.Moreover,the soil properties in the topsoil(0–5 cm) showed larger variation scope than those in the deeper soil layers(5–20 cm).The significant relationships of the soil silt+clay content with the chemical properties mainly appeared in the topsoil.The wind erosion susceptibility of the soil,evaluated by erodible fraction(EF),decreased significantly with increasing H.ammodendron plantation age.Additionally,the annual pioneer herb,Agriophyllum squarrosum,was gradually substituted by the annual salt-tolerant herb,Bassia dasyphylla,with increasing plantation age.These results showed beneficial effects of H.ammodendron plantation on improving soil conditions.However,the dynamics of the herbaceous species also reminded us that the longterm effects of H.ammodendron plantation,especially on changes in vegetation composition,still need further evaluation.     

基于ANSYS Workbench的TZ04DU1.0装载机的有限元分析

针对配套福田欧豹FT404拖拉机的TZ04DU 1.0前装载机,在SolidWorks中建立三维装配体模型,并导入ANSYS Workbench进行静力学分析.根据配普通铲斗装载机的工作要求,建立正常工作情况下的受力模型,对该装载机在两种极限工况下进行有限元分析,计算出整体的应力和应变分布云图,得到结构进一步优化的基础数据,提出一些结构优化方案.     

Weed control,environmental impact and profitability with trifluralin plus reduced doses of imazethapyr in dry bean

Field experiments were conducted in 2003, 2006, and 2007 in Ontario to determine if reduced doses of imazethapyr combined with trifluralin applied pre-plant incorporated (PPI) can be used as an economically and environmentally feasible weed management strategy for broad spectrum weed control in white and kidney bean. There was minimal injury (<5%) in white or kidney bean from imazethapyr applied alone or in combination with trifluralin, regardless of dose. The dose of imazethapyr required for 80 and 95% control of Setaria viridis (L.) Beauv. (green foxtail), Chenopodium album L. (common lambsquarters) and Ambrosia artemisiifolia L. (common ragweed) was reduced when combined with trifluralin (600 g ai ha⁻¹). There was a trend for increased yield of white and kidney bean with increasing doses of imazethapyr applied alone and in combination with trifluralin. Combining trifluralin with imazethapyr increased the environmental impact (EI) by more than ten-fold compared to imazethapyr alone. The lowest dose of imazethapyr used in this study resulted in the lowest environmental risk. The doses of imazethapyr that maximized profit were 38 g ai ha⁻¹ for white bean and 47 g ai ha⁻¹ for kidney bean. Combining imazethapyr with trifluralin will provide growers with a weed management strategy that provides acceptable weed control, with only a small increase in environmental impact, and has the potential to increase yields and net returns.     

土壤及叶面调控对核桃“叶缘焦枯病”的防控效果

[目的]为新疆核桃叶缘焦枯生理病害的防控提供依据.[方法]通过对叶面喷施生理调控剂、土壤调控、叶面喷生理调控剂+土壤调控、对照等4个处理的防控效果试验,研究不同防控处理对核桃病害发生程度、核桃商品性、叶片矿质元素含量和元素比例的影响.[结果]各防控处理对降低核桃病害发生程度、提高核桃商品性、减少叶片中离子失衡,具有显著效果.叶面喷生理调节剂+土壤调控处理的效果最好,可使叶片Na+含量降低18.8;、Ca2含量提高7.4;、Cl含量降低16.3;、Na/K比降低36.0;、Na/Ca比降低24.2;、Cl/N比降低19.4;;与对照相比,增产36.8;,黑缩果率减少70.1;,商品率提高36.4;,增加经济效益1 456元/667m2.叶面喷生理调节剂+土壤调控处理的防效为89.9;,叶面喷生理调节剂的防效为80.1;,土壤调控的防效为63.2;.[结论]叶面喷生理调节剂和土壤调控各处理可有效降低病叶发生率,减少焦枯病斑面积占比,降低病情指数;可显著提高核桃单产,减少黑缩果率,提高商品率;减少Na+和Cl向叶片富集,防止核桃叶片中矿质元素比例失衡,减轻“叶缘焦枯病”症状及危害.