The increasing importance of herbicides in worldwide crop production

Herbicide use is increasingly being adopted around the world. Many developing countries (India, China, Bangladesh) are facing shortages of workers to hand weed fields as millions of people move from rural to urban areas. In these countries, herbicides are far cheaper and more readily available than labor for hand weeding. History shows that in industrializing countries in the past, including the United States, Germany, Japan and South Korea, the same phenomenon has occurred—as workers have left agriculture, herbicides have been adopted. It is inevitable that herbicide use will increase in sub‐Saharan Africa, not only because millions of people are leaving rural areas, creating shortages of hand weeders, but also because of the need to increase crop yields. Hand weeding has never been a very efficient method of weed control—often performed too late and not frequently enough. Uncontrolled weeds have been a major cause of low crop yields in sub‐Saharan Africa for a long time. In many parts of the world, herbicides are being increasingly used to replace tillage in order to improve environmental conditions. In comparison with tillage, herbicide use reduces erosion, fuel use, greenhouse gas emissions and nutrient run‐off and conserves water. © 2013 Society of Chemical Industry     

4％烟嘧磺隆悬浮剂不同施用量对玉米田杂草的药效药害试验

针对玉米常用的苗后除草剂4％烟嘧磺隆悬浮剂,以河北省衡水地区大田生产上常用的夏玉米品种郑单958为试材,在玉米5叶期（此时杂草基本出齐）采用不同施药量（1050、1500和1950 mL/hm2）进行喷施,分别以喷施清水和人工除草为对照,分析不同施药量对杂草防除效果以及玉米安全性和产量的影响,以确定最佳施药量。结果表明：在玉米5叶期用4％烟嘧磺隆悬浮剂进行除草,适宜用量为1500 mL/hm2,不仅对各种杂草防治效果好,而且对玉米不产生药害,玉米产量高。     

Improved GC‐MS/MS Method for Determination of Atrazine and Its Chlorinated Metabolites in Forage Plants—Laboratory and Field Experiments

Abstract

Analytical procedures using gas chromatography–ion trap tandem mass spectrometry (GC‐MS/MS) were developed to analyze atrazine (ATR) and its dealkylated metabolites in four forage species (switchgrass, tall fescue, smooth bromegrass, and orchardgrass). Atrazine, deethylatrazine (DEA), and deisopropylatrazine (DIA) were extracted with methanol (CH₃OH) followed by liquid–liquid extraction and partitioning into chloroform, with additional cleanup by C₁₈ solid‐phase extraction (SPE). Through the optimization of ionization conditions and ion storage voltages, the background noise of product ion spectra (MS/MS) was reduced dramatically, providing sub‐µg/kg detection limits. Mean recoveries of ATR, DEA, and DIA were 94.3, 105.6, and 113.1%, respectively. The estimated limit of detection (LOD) was 0.6 µg/kg for ATR, 1.3 µg/kg for DEA, and 0.3 µg/kg for DIA. These LODs were one to two orders of magnitude lower than those reported for other GC‐MS, GC‐MS/MS, high pressure liquid chromatography (HPLC)‐UV, or HPLC‐MS/MS procedures designed for food‐safety monitoring purposes. To validate the developed method, a field experiment was carried out utilizing three replications of four forage treatments (orchardgrass, tall fescue, smooth bromegrass, and switchgrass). Forage plants were sampled for analyses 25 days after atrazine application. DEA concentrations in C3 grasses ranged from 47 to 96 µg/kg, about 10‐fold higher than in switchgrass, a C4 species. The ATR and DIA concentrations were similar, ranging from 1.5 to 13.2 µg/kg. The developed method provided sufficient sensitivity to determine the fate of ATR and its chlorinated metabolites via plant uptake from soil or dealkylation within living forage grasses. It also represented significant improvements in sensitivity compared to previous GC methods.     

转基因青蒿与其野生型的生长和抗逆性比较

在环境释放条件下,比较了转基因青蒿及其野生型受体的基本农艺性状、抗逆性及耐常用除草剂等特性.在旱、盐胁迫下,通过测定3种转基因品系和其野生型受体的叶片相对含水量、过氧化物酶及脯氨酸等生理指标,比较了转基因青蒿和野生型的耐受性.结果显示,转基因青蒿品系ANF176、GFH13的株高、茎粗显著低于其野生型受体,转基因青蒿品...     

防除滩涂米草入侵的根际缓释方法

为防除滨海滩涂互花米草入侵,探讨根际土壤缓释除草剂的新方法。该研究采用扩散法研究了蛭石、PE膜和合成壳聚糖膜3种缓释材料的根际缓释除草剂的性能,同时,采用根部浸泡试验验证根际施药防除互花米草的效果。结果表明,3种缓释材料的缓释性能差异显著,蛭石对草甘膦控释能力较弱,初始释放农药量最大,释放迅速,适合淤泥质潮滩;PE膜则表现出较强的控释能力,释放量较小,但整个过程释放量较稳定,适合沙质和近根际水体;壳聚糖膜介于两者之间。根部浸泡试验表明,0.25～1.00 g/L草甘膦、0.09～0.23 g/L百草枯、0.28～2.30 g/L草铵膦根部浸泡2～6 d即可显现毒杀互花米草效果,通过饱和土壤一维溶质渗滤模型计算,在点源释放模式下,除草际根部释放点间有效除草间距为50～60 cm。研究证明了根际缓释除草剂防除互花米草具有可行性。     

稻田除草剂对固氮蓝藻的毒性研究

通过4种稻田除草剂对固氮鱼腥藻(AnabaenaazoticaLey)、球胞鱼腥藻(AnabaenasphaericaBorn)、多变鱼腥藻(AnabaenavariabilioKutzing)的毒性进行了研究。结果表明,二甲四氯对3种藻的生长有促进作用,而丁草胺和乙草胺在低浓度(8mg·L-1以下)表现为促进,当浓度为16mg·L-1时,则显著抑制其生长,且高浓度时对3种藻产生较强毒性,处理96h时的EC50值分别为12.87、25.36、20.21mg·L-1及50.52、18.37、45.43mg·L-1。3种藻对扑草净极为敏感,在低浓度时其生长受到严重抑制,继而迅速死亡。因此选择对固氮蓝藻安全的稻田除草剂,对维护稻田生态、促进农业可持续发展具有重要意义。     

浙北稻麦连作区稻田糠稷发生对水稻生长的影响及对除草剂敏感性研究

调研了浙北稻麦连作区稻田糠稷发生及分布状况,并考察了糠稷种子萌发特性和对水稻生长的影响及植株对不同除草剂的敏感性,旨在为有效防治糠稷提供参考。结果表明,糠稷在浙北稻麦连作区直播田发生的相对优势度在0~2.8%、机插田发生的相对优势度在0~3.6%;糠稷种子在光照条件下才能萌发,光照36℃（12 h）/黑暗28℃（12 h）条件下,浓度为1 000 mg/L、500 mg/L的GA3溶液和浓度为0.2%、0.1%的NaOH溶液浸种24 h,糠稷的发芽率超过90%,较清水处理差异显著,说明糠稷种子存在休眠特性;田间糠稷发生密度越高,对水稻株高抑制率和水稻减产量越明显,当糠稷密度达125株/m²时,对水稻株高抑制率达4.17%,水稻减产率达61.42%;低龄或高龄糠稷植株对恶唑酰草胺和敌稗·丁草胺二种除草剂均较为敏感,低龄糠稷植株对五氟磺草胺较为敏感。     

Chlorophyll meter as a tool for forecasting wheat nitrogen requirements after application of herbicides

Because limited information is available about the validated use of a chlorophyll meter for predicting nitrogen requirements for optimum growth and yield of wheat after application of herbicides, field experiments were carried out in the winter seasons of 2011/2012 and 2012/2013 under different weed and N fertilization treatments. Five weeded treatments, application of herbicides 25 days after sowing (DAS), hand pulling once at 55 DAS and a weedy check were combined with four N application rates. Weeds were completely absent in the non-fertilized plots, either with metribuzin or hand pulling as well as in isoproturon-treated plots fertilized with 190 or 285 kg N ha^?1. The grain yield was similar in the treatments of isoproturon × 190 kg N ha^?1, isoproturon + diflufenican × conditional N treatment (113.9) or 190 kg N ha^?1, hand pulling × conditional N treatment (104.8) or 285 kg N ha^?1 and metribuzin × 190 kg N ha^?1. Under weeded practices, conditional N treatment recorded the maximum nitrogen use efficiency and almost equaled the grain protein content of the 190 kg N ha^?1 application rate. N application based on SPAD readings saved about 40.0% and 44.8% N with isoproturon + diflufenican or hand pulling, respectively, compared to the recommended rate (190 kg N ha^?1) without noticeable yield loss.     

玉米对磺酰脲类除草剂敏感性及土壤残留的研究

采用室内模拟添加法、盆栽法和土壤残留动态试验法,分别研究了不同玉米品种对磺酰脲类除草剂的敏感性、磺酰脲类除草剂对敏感玉米品种苗期影响和磺酰脲类除草剂在土壤中的残留期。结果表明:供试玉米品种对磺酰脲类除草剂存在不同程度的敏感性差异,该类除草剂ED50以上浓度对玉米苗期的根长、株高、叶面积有明显的影响。同时,3种磺酰脲类除草剂苯磺隆、噻磺隆和苄嘧磺隆在土壤中的残留期分别为69、79和150d,并且存在着一定的差异。     

福建地区直播稻田禾本科杂草防控药剂及其使用浓度筛选

为有效控制福建地区直播稻田禾本科杂草的危害,以莆田市仙游县游洋乡的水稻种植基地为试验点,选择测定1%噁嗪草酮悬浮剂、10%双草醚悬浮剂和20%氰氟草酯油悬浮剂等3种除草剂对稗草、千金子等禾本科杂草的防治效果,筛选确定最佳除草剂及其理想的田间使用浓度。结果表明:20%氰氟草酯油悬浮剂是防治直播稻田中稗草、千金子等禾本科杂草最佳的除草剂,田间推荐使用浓度为45~105g·hm-2(有效成分)兑水675L·hm-2,药后30d防治效果达均可80.00%以上,无药害产生,对水稻安全。