河北省县域粮食单产及其生产投入要素的时空分异 ——基于1990-2010年统计数据的实证分析

以河北省147个县域为研究单元,借助数理统计和GIS空间分析等方法,揭示1990-2010年粮食单产及其驱动因子的时空演化特征。结果表明:①县域粮食单产“中部高、东西两侧低”与“中南部高、北部低”的层次分异格局非常明显;②县域粮食单产以普遍上升为主,单产水平较高的区域沿京广铁路和京哈高速公路向左右两侧扩张,单产水平较低的区域集中分布在河北北部和河北西部,海河冲积平原区粮食单产上升幅度较快;③县域粮食单产的驱动因素呈现为非均衡联动的局域性特征,耕地有效灌溉面积比重对粮食单产的影响最显著。与1990年相比,2010年4种投入要素对粮食单产的影响系数均在下降,系数为负值的县域明显增加,表明部分县域农业生产投入对粮食单产的边际效应已经达到递减阶段。因此,应结合县域粮食单产的现状和驱动因子的效应机理,积极采取相应措施以保障京津冀地区的粮食安全。     

落叶松毛虫AChE 最佳反应体系建立及其 对3 种杀虫剂敏感性比较

通过正交试验和酶活性测定法研究了落叶松毛虫6 龄幼虫乙酰胆碱酯酶(AChE)最佳反应体系及对3 种杀 虫剂的敏感性。结果表明:落叶松毛虫6 龄幼虫AChE 最佳反应条件为酶液质量浓度0郾2 g/ mL、底物浓度0郾8 mmol/ L、反应体系pH 7郾5、水浴温度35 益和反应时间5 min。敌敌畏、高效氯氟氰菊酯和阿维菌素对落叶松毛虫6 龄幼虫体外AChE 活性产生不同的抑制作用,且抑制效应与杀虫剂呈现明显的剂量鄄效应关系;其中敌敌畏抑制效 果最显著(IC50 =3.018 ·10 -4 mg/ mL),其次是高效氯氟氰菊酯(IC50 = 1.436 ·10 -2 mg/ mL),而阿维菌素对AChE 活性抑制效果最弱。      

政府农村基础设施投资对农户耕地投入的影响评价简

运用VEC模型分析了我国农业政府农村基础设施投资对农户化肥、农膜及农药等生产要素投入的影响,结果表明：我国农业政府农村基础设施投资和农户农地投入具有协整性,两者之间存在长期稳定的关系;国家对农村基础设施投资的增加能够引起农户农地投入的增加,当国家对农村的基础设施建设逐渐健全,农户会相应地增加农业生产的投入,有利于稳定农业生产和保障粮食安全。     

两种杀虫剂防治茶尺蠖药效试验初报

田间试验结果表明,24％艾法迪悬浮剂、15％凯恩乳油对茶尺蠖(Ectropis oblique Prout)具有较好的速效性和较长的持效期,24％艾法迪悬浮剂1 500 mL/hm2及15％凯恩乳油333.3 mL/hm2的防治效果明显高于对照药剂2.5％联苯菊酯乳油1 350 mL/hm2,是防治茶尺蠖的理想药剂,可以大面积推广使用.     

不同温度对蒙古栎种子杀虫效果的影响研究简

蒙古栎种实主要虫害为栗实象鼻虫（Curculiodavidi fairmaire）,常规的方法以热水杀虫为主.本试验对蒙古栎种子在40℃、50℃、55℃、60℃、65℃、70℃、80℃、90℃热水中进行了杀虫试验和发芽率比较,杀虫时间均为30min.结果表明,温度低于50℃,对害虫影响小;温度大于65℃,虽然杀虫率高,但种子失去了芽力.蒙古栎种子在50～ 60℃下杀虫率高,以55℃杀虫率为最高,而且对种子的发芽无影响.     

Past Studies on and Present Status of Lethal Yellowing Disease of Coconuts

Abstract

The symptoms and extent of lethal yellowing disease of coconuts are described. In research into the cause of the disease nutrient deficiencies, fungi, bacteria, nematodes and, more recently, viruses have been investigated without implicating any causal agent. Mechanical and insect transmissions were attempted by a number of methods. The incubation period was shown to be 3–9 months for young palms and 7–15 months for bearing palms. Experiments to control the disease have been unsuccessful.

Local and introduced coconut varieties and hybrids are being tested for resistance by field exposure. The Malayan Dwarf variety has been shown to have high resistance and is being used to replant the industry. No other variety or hybrid is deemed as yet to be sufficiently resistant for farm planting.

Mycoplasms were recently found associated with the disease. Future research must include confirmation of mycoplasm-lethal yellowing association, continuation of the search for the vector, experimental chemotherapy, and attempts to culture mycoplasms to develop an inoculation technique. Palms showing resistance will be used in the breeding programme. Promising hybrids will be produced in greater numbers for more extensive testing and further introductions will be made.     

高效氯氟氰菊酯和啶虫脒及其复配剂对家蚕环境毒性的研究

本文采用食下毒叶法测定了高效氯氟氰菊酯和啶虫脒及其复配剂共8个农药制剂对家蚕2龄幼虫的毒性,结果表明:8种农药不同梯度浓度的药液浸渍桑叶饲喂家蚕后,各药剂对家蚕的LC50值均＜0.5mg/L,对家蚕有极高风险性.     

加工过程对农药残留的影响研究进展

加工过程对农药残留的影响常用加工因子(Processing Factors,PF)来表示。加工不仅可以改善果蔬的食用特性,还对果蔬中农药残留具有重要影响。果蔬在食用前通常经历加工处理有清洗、去皮、烹饪等,某些农产品还会通过腌制、脱水等处理以改善保藏时间和食品风味。本文以常用的家庭处理为出发点,综述了加工过程对农药残留的影响,为确定合适的家庭处理方法提供参考,为膳食暴露评估提供数据依据,从而最大程度的减少食品中农药残留量,以维护消费者身体健康。     

2013年国际食品法典农药残留限量标准最新进展

本文概述了第45届食品法典农药残留委员会农药残留限量标准情况,按照农药类别对标准进行了归类,并分析了标准制修订的主要特点。     

Effects of surfactants and the kinetic energy of monodroplets on the deposit structure of glyphosate at the micro‐scale and their relevance to herbicide bio‐efficacy on selected weed species

The deposit pattern of foliar‐applied agrochemicals, and its relation to their bio‐efficacy, has major practical importance. Thus, in our experiments, we evaluated the relevance of the deposition properties of glyphosate for its bio‐efficacy. The deposition pattern of glyphosate monodroplets was influenced by using surfactant and by applying the droplets with or without kinetic energy to the plant foliage. Monodroplets (1 μL) of glyphosate, formulated with or without ethoxylated rapeseed oil surfactant (RSO) having on average 5, 10, 30 or 60 ethylene oxide units (EO), as well as one commercial glyphosate product (CGP), were applied either by carefully placing the droplet on the foliage with a pipette (kinetic energy assumed to be near zero) or by a monodroplet generator (with kinetic energy). We selected two easy‐to‐wet (Stellaria media and Viola arvensis) and two difficult‐to‐wet (Chenopodium album and Setaria viridis) weed species as target plants. The deposit structure was determined using a scanning electron microscope with energy dispersive x‐ray microanalysis. The kinetic energy of the droplet had no consistent effect on the deposit structure or the bio‐efficacy of glyphosate formulations. In contrast, surfactants differing in EO unit, affected both the deposit structure and the bio‐efficacy of the formulations, depending upon the species. In easy‐to‐wet species, the increase in EO unit of RSO surfactant failed to affect the deposit area of glyphosate and its bio‐efficacy. However, in difficult‐to‐wet species, the increase in EO unit of RSO surfactant reduced the deposit area of glyphosate and enhanced its bio‐efficacy.