无锡茶园不同修剪模式对茶小绿叶蝉发生量的影响

为优化春茶后茶园修剪模式,提高小绿叶蝉控制率,对福鼎大毫和福鼎大白进行不同修剪时间和不同修剪高度的比较,综合结果显示,福鼎大毫以4月28日修剪高度45 cm,小绿叶蝉总控制率最高;福鼎大白以5月25日修剪高度45 cm,小绿叶蝉总控制率达到最高.     

生产效率视域下加工番茄生产要素冗余的区域差异及影响因素

新疆是我国番茄制品生产和出口的重要基地,基于新疆加工番茄主产县域480份农户的调研数据,采用DEA-BCC模型,测算新疆加工番茄主产县域的生产效率,分析加工番茄主产县域的生产要素冗余率,并利用地理探测器模型,揭示影响加工番茄生产效率的关键因子。结果表明：新疆加工番茄主产县域的生产效率存在显著差异,且生产效率均未达到DEA有效水平;其次,加工番茄主产县域的生产要素投入存在不同程度的冗余,种植面积和农业机械投入冗余属于资源利用强度不足型,劳动力、化肥及农药投入冗余属于要素投入过度型;家庭纯收入、户主年龄、户主受教育程度、种植时间和种植面积是生产效率出现县域差异的主要因子,解释力度介于61.4%～65.2%,且因子间相互作用的影响力均高于单独作用的影响力,表明促进县域之间生产要素的合理流动和高效集聚,发挥主产县域的辐射带动作用,可以有效提高加工番茄种植户的生产效率。     

An investigation into the grazing efficiency of perennial ryegrass varieties

The objective of this study was to compare the grazing efficiency of 30 perennial ryegrass varieties, differing in ploidy and heading date. Plots were grazed by lactating dairy cows and managed under a rotational grazing system with 19 grazing events occurring over two years. Pre-grazing and post-grazing compressed sward heights were measured with a rising plate meter. A mixed model was used to predict the post-grazing sward height of each variety based on year, grazing event, block and pre-grazing sward height. Residual grazed height (RGH) was derived as the difference between the actual and predicted post-grazing sward height and was used as the measure of grazing efficiency. Negative RGH values indicated that the actual herbage removed was greater than that predicted and so indicated a superior grazing efficiency. Varieties differed in their level of grazing efficiency (p < .001), with RGH values ranging from −0.38 to +0.34 cm. Tetraploid varieties exhibited significantly greater grazing efficiency performance than diploids (p < .001), with average RGH values of −0.13 and +0.13 cm respectively. A significant difference in grazing efficiency was found among recommended perennial ryegrass varieties that are not being recorded by mechanically harvested simulated grazing protocols. A variety reappraisal that included grazing efficiency could identify varieties capable of improving on-farm livestock productivity from grass.     

新疆生产建设兵团第四师71团玉米密植高产全程机械化生产技术模式发展调研

从种植品种、种植密度与种植方式、机械化作业和收储烘干等环节对新疆生产建设兵团第四师71团场玉米生产技术的发展进行调研。分析表明,71团场位于西北灌溉玉米区,通过规模化、标准化生产和统一作业管理,以密植增产为基础、子粒收获为核心、绿色防控与秸秆还田为保障构建的玉米密植高产全程机械化绿色生产技术,实现了高产和高效的协同提高与绿色可持续生产。经农业农村部专家指导组田间测产验收,2012年、2014年和2017年连续创造16701 kg/hm^2、18414 kg/hm^2和18447 kg/hm^2的全国玉米大面积(700 hm^2)高产纪录,净利润在15000元/hm^2以上,为现代玉米生产树立了成功的模式和样板。     

Relay-intercropping soybean with maize maintains soil fertility and increases nitrogen recovery efficiency by reducing nitrogen input

Optimized nitrogen(N)management can increase N-use efficiency in intercropping systems.Legume-nonlegume intercropping systems can reduce N input by exploiting biological N fixation by legumes.Measurement of N utilization can help in dissecting the mechanisms underlying N uptake and utilization in legume-nonlegume intercropping systems.An experiment was performed with three planting patterns:monoculture maize(MM),monoculture soybean(SS),and maize-soybean relay intercropping(IMS),and three N application levels:zero N(NN),reduced N(RN),and conventional N(CN)to investigate crop N uptake and utilization characteristics.N recovery efficiency and 15N recovery rate of crops were higher under RN than under CN,and those under RN were higher under intercropping than under the corresponding monocultures.Compared with MM,IMS showed a lower soil N-dependent rate(SNDR)in 2012.However,the SNDR of MM rapidly declined from 86.8%in 2012 to 49.4%in 2014,whereas that of IMS declined slowly from 75.4%in 2012 to 69.4%in 2014.The interspecific N competition rate(NCRms)was higher under RN than under CN,and increased yearly.Soybean nodule dry weight and nitrogenase activities were respectively 34.2%and 12.5%higher under intercropping than in monoculture at the beginning seed stage.The amount(Ndfa)and ratio(%Ndfa)of soybean N2 fixation were significantly greater under IS than under SS.In conclusion,N fertilizer was more efficiently used under RN than under CN;in particular,the relay intercropping system promoted N fertilizer utilization in comparison with the corresponding monocultures.An intercropping system helps to maintain soil fertility because interspecific N competition promotes biological N fixation by soybean by reducing N input.Thus,a maize-soybean relay intercropping system with reduced N application is sustainable and environmentally friendly.     

大红犀猎蝽对草地贪夜蛾3龄幼虫捕食功能反应

为探明天敌昆虫大红犀猎蝽Sycanus falleni对草地贪夜蛾Spodoptera frugiperda幼虫的捕食潜力,在室内条件下测定大红犀猎蝽3龄若虫和成虫对草地贪夜蛾3龄幼虫的捕食功能反应、搜寻效应,以及不同自身密度对捕食草地贪夜蛾的干扰反应。结果表明:大红犀猎蝽3龄若虫和成虫对草地贪夜蛾3龄幼虫的捕食功能反应符合Holling II模型;其中大红犀猎蝽3龄若虫对草地贪夜蛾3龄幼虫的日最大捕食量、瞬时攻击率和处理时间分别为4.049头、1.198和0.247 d;大红犀猎蝽雌成虫对草地贪夜蛾3龄幼虫的日最大捕食量、瞬时攻击率和处理时间分别为47.619头、0.717和0.021 d;大红犀猎蝽雄成虫对草地贪夜蛾3龄幼虫的日最大捕食量、瞬时攻击率和处理时间分别为43.478头、0.650和0.023 d;大红犀猎蝽的捕食量与害虫密度正相关,搜寻效应与害虫密度负相关。大红犀猎蝽自身密度对捕食作用的干扰效应符合Hassell模型,对草地贪夜蛾3龄幼虫的捕食作用率随自身密度的增加而降低。表明大红犀猎蝽3龄若虫和成虫对草地贪夜蛾3龄幼虫均有一定的捕食能力,大红犀猎蝽成虫的捕食作用大于3龄若虫。     

不同控释氮肥运筹对粳稻养分吸收与氮素利用的影响

以绥粳18为供试材料,通过盆栽试验,在一次性施入控释氮肥免追肥条件下,设置不同施肥量(高、中、低、无)和施肥深度(5 cm、10 cm),探讨不同氮肥施用方式对粳稻养分吸收和氮素利用的影响。结果表明,在不同氮肥运筹条件下,粳稻各生育期氮、磷、钾的吸收、转运均存在明显的协同效应,施肥深度5 cm组,随着氮肥施用量的增加,粳稻的氮吸收总量增加,同时可促进磷的吸收,但影响幅度较小。钾变化与氮、磷变化有所不同。施肥深度10cm组,施高量氮肥抑制了粳稻对磷的吸收、减少了对氮的吸收,但有利于提高氮素利用率,对钾的吸收无显著影响。施用树脂包膜控释肥,纯氮用量为153 kg/hm^2、施肥深度5 cm、一次性施肥免追肥可获得最优水稻氮素利用效率并显著提高磷钾肥利用效率。     

担保企业风险承担对其企业效率的影响及治理对策

在全社会都必须高度重视金融风险的背景下,厘清担保企业风险承担对其企业自身效率的影响至关重要.利用DEA-Tobit两步法,选取代表性的担保企业样本数据,在测算样本企业2014-2017年运行效率的基础上,实证检验了担保企业风险承担对其企业效率的影响.研究发现:样本期间担保企业的运行效率总体上呈现出先下降再上升的变动趋势,且不同担保企业的运行效率存在明显差异;无论是以担保代偿率、净资产放大倍数还是风险准备金覆盖率作为代理变量,担保企业风险承担对其企业效率均存在明显的负向影响,说明担保企业风险承担显著降低了企业运行效率.当前,担保企业必须增强抗风险能力,就此应该尽快转变经营模式,实现多元化经营,促进其运行效率有效提升和可持续发展.     

沉淀法制备的紫杉醇白蛋白微粒包封率测定

采用沉淀法制备紫杉醇白蛋白微粒,采用高效液相色谱法(HPLC)测定紫杉醇质量浓度,以二氯甲烷为有机相,采用萃取法分离白蛋白微粒与游离药物,测定其包封率。结果表明:紫杉醇在10~100 mg·L-1范围内线性良好,平均回收率可达到97.6%~101.0%;有机溶剂萃取法测定紫杉醇白蛋白微粒包封率的平均回收率,达94.80%~101.67%。这种方法测定紫杉醇白蛋白微粒回收率准确可靠,适用于沉淀法制备的白蛋白微粒的包封率测定。     

太原市森林公园林带对空气PM2.5的净化效率

开展城市绿地滞尘效应研究对指导城市绿地建设具有重要科学意义。为了研究城市交通主干道周边绿地的滞尘效应,以太原市森林公园西侧紧邻滨河东路南北长600 m,东西宽100 m的针叶混交林带为研究对象,在林带最西侧与道路交界处设对照点（0 m）,由西向东垂直于路面在林带内分别设置20、40、60、80 m 4个监测点,用中流量大气PM2.5采样器（100 L/min）在各点对PM_2.5进行日间采样,分析林带内PM_2.5浓度的变化特征并计算林带对PM_2.5的净化效率。结果表明:1）林带宽度影响其对大气PM_2.5的净化效率,从20~60 m的净化效率逐渐提高,80 m处略低于60 m;2）林带对局部空气PM_2.5净化效率与区域空气质量呈负相关,当空气质量为优良时,林带可以有效地降低局部PM_2.5,当空气质量为中重度污染时,林带20~40 m宽处会聚集较高浓度的PM_2.5;3）林带内分时段净化效率显示,9:30-11:00的净化效率最低,12:30-17:00净化效率较高,且15:30-17:00林内PM_2.5质量浓度最低,提示该时段适宜市民在公园内活动。