浅议通过标签内容查找农药隐性成分

本文针对农药隐性成分危害大和监管难等问题,剖析了企业主要动机,以农药标签为对象,研究建立了一种查找"问题"农药、锁定农药隐性成分的方法。该方法具有成本低、易于普及、克服检测仪器谱库不足、发挥基层各方力量进行监管等优点。与检测技术结合使用,可以弥补各方不足,更好地发挥监管作用。     

脉冲式烟雾水雾机热力雾化水剂农药效果分析

针对脉冲式烟雾水雾机在喷施水雾剂农药时常出现滴液、流液或较大雾滴群等雾化不良现象，通过改装6HYW-60S型脉冲式烟雾水雾机，将药液流量设置成可调的测试装置，设定5个油门开度及4个药液流量，测试了脉冲发动机喷药前后的气流速度、温度及各喷药工况下的雾滴粒径分布。结果表明，在最小的油门启动开度到最大的油门工作开度可调范围内，对应的脉冲发动机燃油消耗率变化范围较小（相对变化13.0%），喷管内对应的气流温度与速度也发生同等程度的变化。喷药时，喷管口处的气流温度与速度发生明显变化，由不喷药时约700℃的高温气流下降为75℃左右的雾滴流，相应的气流速度下降了16%左右；油门开度及药液流量对雾滴流温度的影响非常小，但对雾滴流速度的影响非常明显，油门开度增大，雾滴流速度明显增加，药液流量增大，雾滴流速度明显下降。在各油门开度下，对最小药液流量20L/h的雾化效果均不佳，尤其距喷雾出口较近处存在大量的300μm以上的较大雾滴，这些大雾滴极易跌落至地面，无法有效喷施到目标物上；药液流量增大至40L/h及以上时，各油门开度下的雾滴体积中径均较小，同一工况下各位置点的平均值不超过60μm。热力雾化的雾滴粒径分布曲线不是单一峰值的正态分布形态，常会出现不同中心雾滴粒径的雾滴群，且这些雾滴群的中心雾滴粒径基本保持一致。从喷雾出口喷出的雾滴流中，喷管中心轴线上的雾滴细小均匀、雾化充分，中心轴线上方的雾滴一般比中心点处稍大，中心轴线下方雾滴明显增大，且距中心轴线越远的下方，雾滴增大越明显，即雾滴流中较大雾滴群的量逐渐增加。以药液流量60L/h及油门开度90°为最佳雾化工况，在整个喷施区域内均形成了良好的雾化效果。     

全元生物有机肥对蔬菜作物生长及产量的影响

为了验证全元生物有机肥对蔬菜作物生长的促进作用与增产效应,本文以”江蔬一号”丝瓜为试验作物进行小区对比试验,探究全元生物有机肥施用对作物叶绿素含量、丝瓜产量的影响。结果表明,新型全元生物有机肥处理丝瓜单瓜的干重和鲜重均最高,其他处理产量高低依次为普通有机肥-化肥配合施用、单施有机肥、单施化肥、完全不施肥处理。     

Prevention and Controlling Effect of Intercropping on Pests and Diseases and Its Risk Control in Cotton Fields

Cotton is one of the major field crops which are seriously threatened by pests and diseases. In recent years, the ecological management of cotton pests and diseases with intercropping has become to be an interesting approach. Intercropping possibly increases the population of natural enemies and finally reduces the population density of pests as a result of changes in ecological structure and environmental conditions of farmland. Intercropping thus has been considered an important alternative in controlling pests and diseases. However, cotton field intercropping also has some limitations in controlling pests and diseases. Unreasonable intercropping system has many risks such as increasing labor input, increasing the difficulty of pests’ control, and aggravating pests and diseases. In this paper, the effects and the underlying mechanisms of cotton intercropping on cotton pests and diseases were reviewed. The possible risks and countermeasures used for ecological control of intercropping were also put forward, and the future and application of ecological management of cotton pests and diseases with intercropping were prospected.     

茶树凋落叶浸提液对菘蓝生理生化的化感效应

为研究茶树凋落叶浸提液对菘蓝生长与生理生化的化感效应,以模拟自然条件下雨雾淋溶方式,采用不同浓度的茶树凋落叶浸提液(CK:0 mg·mL^-1、T1:6.25 mg·mL^-1、T2:12.5 mg·mL^-1、T3:25 mg·mL^-1 和T4:50 mg·mL^-1)处理菘蓝,测定其生长、抗氧化酶活性及其基因表达量、细胞膜损伤率以及丙二醛(MDA)、过氧化氢(H₂O₂)、渗透调节物质和次生代谢物含量的变化。结果表明,茶树凋落叶浸提液对菘蓝生长表现出“低促高抑”的浓度效应,与CK相比,T1对菘蓝生长具有一定的促进作用,而浸提液浓度超过菘蓝的耐受阈值时,会对其生长产生不利的影响。随着浸提液浓度的升高,可溶性糖和可溶性蛋白含量呈先上升后下降的趋势,而脯氨酸含量则持续增加。与CK相比,T1的MDA含量、细胞膜损伤率和H₂O含量差异不显著,而T3、T4则显著升高。茶树凋落叶浸提液对抗氧化酶活性及其基因表达有不同的影响,T1的过氧化物酶(POD)与抗坏血酸氧化物酶(APX)活性最高,T2的过氧化氢酶(CAT)活性最高,而T3、T4的4种抗氧化酶活性均显著低于CK。T1的Pod、Cat、Apx基因表达量最高,而T4则抑制了抗氧化酶基因的表达。此外,POD活性与其基因表达量呈显著正相关,而超氧化物歧化酶(SOD)、CAT和APX活性与其基因表达量的相关性不显著。不同浓度的茶树凋落叶浸提液对于菘蓝次生代谢物质积累的影响存在显著差异,低浓度茶树凋落叶浸提液对菘蓝生长、靛蓝和靛玉红含量积累有促进作用,而高浓度茶树凋落叶浸提液对总黄酮含量积累有一定的促进作用。本研究结果可为幼龄茶园中茶树-菘蓝复合种植提供理论参考。     

华北平原不同种植制度对粮食作物氮素利用和土壤氮库的影响

冬小麦-夏玉米一年两熟是华北平原粮食作物的主要种植制度，存在氮肥利用率低、土壤氮素过量累积问题。为探索华北平原氮素高效利用的适宜种植制度，采用15N示踪技术，基于3 a田间定位试验，对一年两熟冬小麦-夏玉米的常规水氮和优化水氮、两年三熟冬小麦-夏玉米-春玉米与冬小麦-夏大豆-春玉米及一年一熟春玉米3种种植制度的作物产量、15N利用率、氮素去向和土壤氮库表观平衡进行研究。结果表明，两年三熟的冬小麦-夏玉米-春玉米产量为32 248.52 kg/hm2，分别比一年两熟和一年一熟提高22.16%和52.88%；15N利用率为33.36%，比一年一熟提高26.12%。3种植制度的氮肥去向最高为土壤残留，其次为作物吸收和损失，两年三熟冬小麦-夏玉米-春玉米的作物吸氮量最高为151.82 kg/hm2，土壤氮库表观盈余量为21.22 kg/hm2，显著低于其他种植制度。综合分析，冬小麦-夏玉米-春玉米两年三熟在稳产高产和提高氮素利用率上具有可持续的潜力，是华北平原未来较为理想的种植制度。     

基于状态变换法的车辆悬架系统时滞反馈控制

为了提高车辆行驶平顺性和稳定性,研究悬架系统中时滞补偿控制效果,本文以赛欧轿车悬架系统为基础,建立2自由度车辆半主动悬架系统模型,设计了时滞反馈控制器,采用理论与试验相结合的方法对系统时滞反馈控制特性进行研究。首先建立含时滞的悬架系统动力学方程,采用常微分理论和多项式判别方法分析系统稳定性,并通过时域与频域仿真对结果进行验证。研究表明:采用传统二次型最优控制律对含时滞的悬架系统进行控制,当系统控制时滞较大时,系统定性特性可能会发生改变,甚至会失稳发散。为保证系统的稳定性,采用状态变换方法设计时滞反馈最优控制律,仿真表明采用该控制律不仅可以保证系统稳定性,系统的减振特性亦有改善。最后搭建了悬架时滞反馈控制平台,基于时域辨识方法测得系统固有时滞为0.065 s,通过对相同工况下仿真结果与试验结果进行对比,发现两者具有较好的一致性,误差在15%以内,满足业内使用要求,表明研究可信,结果可为主动/半主动车辆悬架控制器实际设计应用提供参考。     

不同间作绿肥替代化肥模式对木薯性状和产量的影响

通过探讨秸秆还田与化肥减施下间作绿肥对木薯产量性状的影响,着力解决连作木薯土壤肥力提高与改良相关技术的协调增效。于2019-2020年,以木薯品种“南美1号”为供试材料,设置8个处理,调查每个小区的木薯茎径、叶绿素（SPAD）、块根直径、块根长、单株茎秆鲜重、单株块根鲜重、株高、单片叶重、单株块根数以及小区产量等农艺性状。结果表明,处理5（木薯秆还田+化肥减量12.5%+12.5%营养元素当量黑豆绿肥还田）的木薯产量最高,并得到拟合方程。绿肥秸秆还田以及间作绿肥从整体上改良了土壤肥力,并通过显著影响木薯块根、单片叶重以及单株块根数而影响最终产量。     

Effects of formic acid and potassium diformate on the fermentation quality,chemical composition and aerobic stability of alfalfa silage

The objective of this study was to evaluate the efficacy of potassium diformate (KDF) as a potential additive for alfalfa silage. Fresh alfalfa was untreated or treated with formic acid (4 g/kg fresh weight, FW) or three concentrations of KDF (4, 5.5 or 7 g/kg FW). After 60 days of ensiling, the addition of formic acid and greater levels of KDF (5.5 and 7 g/kg) effectively reduced silage pH and inhibited the undesirable bacteria, indicated by lower butyric acid, ethanol, ammonia N concentrations and microbial populations (including enterobacteria, yeasts, moulds and clostridia). Additives decreased the dry‐matter loss, and more water‐soluble carbohydrates were preserved in the silages with formic acid or potassium diformate than in the control. Alfalfa silages treated with formic acid at 4 g/kg FW or potassium diformate at 5.5 or 7 g/kg FW were classified as the highest quality silage based on the higher Flieg's point (above 70) and remained stable for more than 9 days during aerobic exposure. Potassium diformate is recommended as an effective additive for alfalfa silages at a level of 5.5 or 7 g/kg FW under the humid and hot conditions of southern China.     

Biochar has little effect on soil dissolved organic carbon pool 5 years after biochar application under field condition

Biochar application can improve soil properties, such as increasing soil organic carbon content, soil pH and water content. These properties are important to soil dissolved organic carbon (DOC); however, the effects of biochar on DOC concentration and composition have received little research attention, especially several years after biochar application under field conditions. This study was conducted in a long‐term experimental field where the biochar was only applied once in 2009. The purpose of the study was to investigate the effect of different biochar application rates (0, 30, 60 and 90 t ha^?1) on the dynamics of soil water content, DOC concentration and DOC compositions (reducing sugar, soluble phenol and aromatics) over nine samplings during a 12‐month period in 2014. Our results showed that soil water content and DOC concentration varied from 7.1% to 14.5% and 59 to 230 mg C kg^?1 soil during the 12 months, respectively. However, the biochar application rates did not significantly (p > 0.05) affect soil water content, DOC concentration and DOC composition at the same sampling period. The DOC concentration across the biochar treatments was positively correlated to soil water content. Moreover, the DOC composition (reducing sugar, soluble phenol or aromatics) and their concentrations were positively correlated to the total DOC concentration. In addition, biochar did not affect soil bulk density, pH, saturated hydraulic conductivity and crop yields. The results indicated that some benefits of biochar to soil may not persist 5 years after the application of biochar under a field condition.