Assessing the deposition and canopy penetration of nozzles with different spray qualities in an oat (Avena sativa L.) canopy     

《Crop Protection》2016

Consistent spray coverage that is evenly distributed throughout the canopy is necessary to control pest populations that can negatively affect yield. As applicators are switching to Coarser spray quality nozzles to reduce risk and liability of pesticide spray drift, concerns about efficacy loss are growing. Previous research has indicated that small droplets are the most effective at penetrating through crop canopies, but newer nozzle technologies have improved the effectiveness of larger droplet or Coarser sprays. Research was conducted to assess the canopy penetration of nozzles that produce Coarse, Very-Coarse and Extremely-Coarse spray qualities compared to nozzles that produce Fine and Medium spray qualities. Kromekote collectors were positioned in four configurations in an oat (Avena sativa L.) var. ‘Yarran’ (AusWest Seeds, Forbes, NSW, Australia) crop to quantify the coverage and droplet number densities (droplets cm⁻²) across three application carrier volume rates: 50, 75 and 100 L ha⁻¹. Applications were made in the field in 30 cm tall, tillering oats, with collectors arranged in a randomised complete block design with three replications. The entire study was repeated on the following day. Results showed that droplet number densities were inversely related to the droplet size produced by the nozzles, yet coverage was increased more by application volume rate than droplet size. Thus, both spray drift reduction and improved canopy penetration can be achieved with proper nozzle selection and operation parameters for the control of agronomic pests.  相似文献   

Farmers' knowledge and perception of grain legume pests and their management in the Eastern province of Kenya     

《Crop Protection》2016

Grain legumes play an important role in community livelihood and in the national economy in Kenya. Unfortunately, in many African countries, production doesn't satisfy the demand in grains due to various constrains. Understanding farmers practices and behavior in the management of grain legume pests is a crucial step in the development of sustainable management strategies. A total of 216 farmers were surveyed in eight districts of eastern Kenya to evaluate farmers' knowledge and perceptions of grain legume pests; to examine current pest management practices, and to identify other production constraints. Grain legumes are grown by a wide age-group of farmers, with both genders equally represented. Chemical control remains the main pest management strategy, and, to ensure pesticide effectiveness, farmers also use increased application rates, chemical alternation, frequent application and mixtures of chemicals. While farmers used other control measures, they showed only limited interest in biological control. The majority of the farmers had experience in grain legume farming and were able to identify the major pests, which were the legume flower thrips Megalurothrips sjostedti Trybom, the cowpea aphid Aphis craccivora Koch and the legume pod borer Maruca vitrata Fabricius. Our survey revealed that education and proximity to extension services contributed significantly to farmers' knowledge of grain legume pests, suggesting the need to provide continuous training and capacity building on integrated pest management in grain legume farming. The study also suggests integration of other pest management strategies such as the use of early maturing varieties, biopesticides and biofertilizer to reduce the use of chemical for sustainable pest management.  相似文献   

基于热力学定律的太阳能利用探究     

别业广  杨晓艳 《湖南农机》2007,(1):138-139

本文对太阳能的起源、传播、与物质的相互作用以及储存和利用等各个方面所涉及的物理学定律,特别是对太阳能热利用所涉及的热力学定律进行了概括和归纳。根据热力学定律指出太阳能热利用的真正适用范围。  相似文献   

Calculation of Maintenance Cost Based on the Proportional Life Setback Model     

ZHANG Wei-feng  TANG Sheng-li 《保鲜与加工》2006,(5):52-54

Maintenance cost is one of the most difficult parts to calculate in variant-cost, for it s decided by the reliability of components. As an important factor of reliability, life is largely affected by maintenance. The proportional life prolonged model based on maintenance is presented firsdy. Based on this model, the function of Mainenance--Life--Cost is deduced. Which provides a new method for power plant to calculate maintenance cost more accurately.  相似文献   

Synthetic Evaluation of Talent Effectiveness Considering Talent Structure     

CHEN An-ming 《保鲜与加工》2007,(8):149-152159

Based on the widening of definition of talent effectiveness, using the indexes of talent structure and economic output types, many indexes of talent effectiveness are built up. A synthetic evaluation of regional talent utilization efficiency is presented based on principal components analyses. The result indicates that the talent utilization efficiency in east China is higher distinctly than in middle and west China and the talent utilization efficiency in middle is close to in west China without obvious hierarchy distribution  相似文献   

贵阳地区水稻中甲胺磷农药残留研究     

张卫兵  李明 《种子》2002,(6):39-40

甲胺磷（methamidophos）具有内吸、触杀和胃毒杀作用，防治抗性蚜、蟥和水稻叶蝉、悦虱等药效较好，但残留期较长，有时会影响作物的品质。通过对贵阳地区水稻中甲胺磷农药残留分析，得到贵阳地区的大米中甲胺磷未检出。样品以丙酮提取，经过盐析、再经二氯甲烷萃取后进行气相色谱分析（最低检测浓度为0.03μg/g），本方法的结果符合农药残留分析的要求，因此说明贵阳地区的大米中甲胺磷没有超标，为贵阳地区绿色食品的开发提供理论依据。  相似文献   

化学镀镍单板的导电性和电磁屏蔽效能   总被引：2，自引：0，他引：2  

黄金田  赵广杰 《林产工业》2006,33(1):14-17

为了实现单板的导电性和电磁屏蔽效能,对单板进行了化学镀镍研究,通过表面电阻率和电磁波网络分析仪测量方法对化学镀镍单板的导电性和电磁屏蔽效能进行了分析。结果表明：化学镀镍单板的导电性随着金属镍沉积量的增加而增加,但单板的导电性具有各向异性,平行于纤维方向的导电性要好于垂直于纤维方向的导电性。此外,这种各向异性在金属镍沉积量较少的情况下表现得更加明显,化学镀镍单板的电磁波屏蔽效能随着由于金属镍沉积量的增加而引起导电性的增加而增大,在本研究中化学镀镍单板的电磁波屏蔽效能可以达到30～60dB。  相似文献   

我校思想政治理论课教学实效性调查研究     

郑再喜  贺尧夫  范明水  费秋香 《华南热带农业大学学报》2007,13(4):101-103

通过调查问卷了解学生对思想政治理论课教学效果的看法,掌握我校大学生对思想政治理论课程开设和教学的真实感受及心态,为准确把握学生对思想政治理论课程教学的认识和态度提供较为可靠的第一手材料,为提高我校思政类课程教学的针对性和实效性提供参考。  相似文献   

自然降雨对干化土壤水分恢复有效性分析     

汪星  张敬晓  汪有科  吕望  路梅  辛小桂 《水土保持学报》2021,35(1):161-168

研究自然降雨对干化土壤水分恢复的有效性,有利于合理利用降水资源,加强干化土壤水分管理,促进土壤干层得到有效恢复。在陕北米脂试验站设置野外地下大型土柱,通过2014—2019年连续定位监测降雨、土壤含水率状况,分析自然降雨对干化土壤水分恢复的有效性。结果表明:(1)从深层干化土壤水分恢复角度考虑,黄土丘陵半干旱区降雨可以分为3种类型:表层入渗快速蒸发型、浅层入渗缓慢蒸发型和深层入渗补给型。其中深层入渗补给型降雨为有效降雨,该类型雨量>26 mm,能够对深层干化土壤产生有效水分补给。2014—2019年发生深层入渗补给型降雨仅16次,累积雨量791.8 mm,降雨次数、降雨量的有效率分别为4.64%和35.19%。(2)月尺度条件下,降雨量(P月)与逐月入渗深度(Z逐月)、月累积入渗深度(Z累积)均呈二次函数关系变化,Z逐月=-0.0102P月2+3.955P月-6.7335(R^2=0.9639),Z累积=-0.0003P月2-0.1331P月+191.71(R^2=0.9208)。(3)年尺度条件下,2014—2019年雨量分别为187.6,391.6,590.8,337.6,342.4,400.0 mm,降雨逐年引发的入渗深度依次为160,220,400,260,260,120 cm,累积入渗深度依次可达180,220,400,700,1000,1400 cm。研究结果对揭示自然降水恢复干化土壤机理,加强土壤干层人工蓄水保墒技术,合理选择保墒措施,以及促进当地生态环境建设具有积极的推动作用。  相似文献   

长江上游梯级电站开发区泥石流的治理工程效果评估与减灾策略——以金沙江白鹤滩水电站为例     

胡桂胜  陈宁生  赵春瑶  李俊  苏立 《水土保持通报》2017,37(1):241-247,269

[目的]评估灾害性泥石流严重的长江上游梯级电站开发区泥石流灾害治理工程效果,为长江上游同类水电站的泥石流防灾减灾与治理效果评估研究提供思路。[方法]选择金沙江白鹤滩水电站施工区的矮子沟和大寨沟泥石流治理工程为案例,通过2013—2015年连续3a的现场跟踪调查分析,结合模型计算对矮子沟和大寨沟泥石流峰值流量过程进行计算,分别评估2014和2015年矮子沟、大寨沟泥石流治理工程效果,并进行泥石流危险性评价。[结果]基于长江上游梯级电站开发区泥石流灾害特点,提出了长江上游梯级电站开发区泥石流治理工程效果评估模式,并提出了基于风险控制的水电工程泥石流"以排为主,适当拦挡"治理模式与减灾策略。[结论]矮子沟、大寨沟现有的泥石流防治措施在满库的状态下能够满足500年一遇泥石流过流的要求,泥石流危险性小。  相似文献