6个不同水稻品种对异丙甲草胺的敏感性差异

为探究水稻对异丙甲草胺的敏感性,选育耐药性品种及为异丙甲草胺水田安全应用提供理论依据,用琼脂培养法室内测定了‘T优15’、‘株712s’、‘深两优5814’、‘T优227’、‘湘丰优9号’、‘丰源优272’等6个水稻品种对异丙甲草胺的敏感性。结果表明,异丙甲草胺对水稻发芽、苗与根的生长均有较强的抑制作用,异丙甲草胺浓度越高抑制作用越大。并且根比苗更为敏感,在异丙甲草胺浓度为0.05mg/L时,6个品种根长抑制率分别为38.7%、34.2%、28.4%、16.1%、16.4%、25.1%,苗高抑制率分别为7.6%、6.3%、8.2%、8.9%、18.3%、5.5%。6个水稻品种中,‘丰源优272’对异丙甲草胺耐受性最高,异丙甲草胺对其苗高、苗重、根长、根重的IC50分别为0.958 9、1.867 4、1.093 9、3.968 2mg/L。     

丙炔氟草胺与精异丙甲草胺复配对花生田杂草的防除效果

为明确丙炔氟草胺、精异丙甲草胺的联合作用效果和50%丙炔氟草胺·精异丙甲草胺SE(悬乳剂)对花生田杂草的防除效果以及对花生的安全性,采用土壤喷雾法测定2种除草剂室内联合作用试验,并对筛选的50%丙炔氟草胺·精异丙甲草胺SE进行田间药效试验。丙炔氟草胺、精异丙甲草胺以质量比1∶9复配对花生田一年生杂草的联合作用较好,50%丙炔氟草胺·精异丙甲草胺SE的推荐使用剂量为600～750 g a. i./hm~2,施药后45 d对杂草的总体鲜重防效可达到93. 5%～96. 4%。丙炔氟草胺、精异丙甲草胺复配互补性强,对反枝苋等杂草增效作用明显,50%丙炔氟草胺·精异丙甲草胺(SE)能够有效防除花生田一年生杂草,并对花生安全。     

多种除草剂防除高粱田杂草的研究

为明确25％绿麦隆WP等6种除草剂防除高粱田杂草的效果及对高粱的安全性,进行了田间小区试验,观察各药剂对高粱田主要杂草的控制作用及对高粱产量的影响.结果表明,每667 m2施用38％莠去津SC 125 mL+96％精异丙甲草胺EC 45 mL,或单施96％精异丙甲草胺EC 90 mL,或单施40％异丙草·莠SC 60 mL,对高粱田稗草、马齿苋、反枝苋、藜等杂草均有较好的防治效果,高粱产量也有显著提高.     

控制释放制剂的组成对异丙甲草胺释放速率的影响

将海藻酸盐与膨润土复合作为载体制备除草剂异丙甲草胺的控制释放制剂,研究了载药量、载体原料配比、膨润土类型等制剂组成因素对异丙甲草胺释放速率的影响。采用Ritger和Peppas方程分析释放动力学过程,计算50%的异丙甲草胺被释放所需时间(t50),并以此表征释放速率。结果表明,采用海藻酸盐/膨润土复合载体时, t50随载药量和载体原料配比不同介于29.4~68.0 h 之间,控制释放效果明显优于单纯以有机改性膨润土作载体(t50=5.9 h)。将有机改性膨润土与海藻酸盐复合作载体时,t50可达110 h。释放动力学方程的n值(0.436~0.496)接近Fickian扩散模型,说明该控制释放制剂中异丙甲草胺的释放过程主要受到扩散控制。     

生测法测定甲草胺在土壤中的残留量

根据甲草胺对敏感植物的幼根或幼茎有抑制作用的原理,采用培养皿土培方法,通过测量发芽种子的根、茎长度来测定甲草胺在土壤中的残留量。实验室筛选试验表明,豌豆、黄瓜幼根及燕麦、小麦幼茎是测定甲草胺在土壤中残留量的敏感试材。豌豆及黄瓜的根部对甲草胺的敏感浓度线性范围较宽,为0.1—8.0微克/克土,IC_(50)(在草甸黑土中抑制根长50％所需要的甲草胺浓度)为3.23ppm±0.20及2.3ppm±0.16;燕麦及小麦茎部的敏感范围较窄,为0.5—5.0微克/克土,IC_(50)为1.3 ppm±0.10及2.8 ppm±0.15。用豌豆根生测法测定甲草胺在田间土壤中的消解动态表明,甲草胺在花生田草甸黑土中降解较快,半衰期为3天左右,其结果与气相色谱法接近。     

精异丙甲草胺在土壤中的吸附行为及环境影响因素研究

采用平衡振荡法研究了精异丙甲草胺在粘壤土、粘土及砂壤土中的吸附和解吸附行为。结果表明,3种土壤的吸附等温线均属L型并符合Freundlich模型,吸附常数(Kf)分别为4.01、6.15及8.62,且Kf 和1/n(n为经验常数)的乘积与土壤有机质含量呈正相关性。解吸附实验结果表明,精异丙甲草胺在土壤中的解吸附与吸附并不一致,显示出明显的滞后性。温度及pH值等环境因素对吸附影响的结果显示,随温度升高精异丙甲草胺在土壤中的吸附量有所减少,中性环境下土壤吸附量较低。     

几种酰胺类选择性除草剂的特性

自盂山都公司于1956年开发成功旱田除草剂二丙烯草胺后,酰胺类除草剂有较大发展,到目前已有53个品种商品化,其中氯代乙酰胺类占主导地位。目前得到市场广泛认同的氯代乙酰胺类除草剂主要包括甲草胺、乙草胺、丙草胺、丁草胺、异丙草胺、异丙甲草胺、精异丙甲草胺等7种,它们是高效、高选择性除草剂,大多数用于防除一年生禾本科杂草。     

4种酰胺类除草剂对玉米的安全性及药效

室内外测定了4种酰胺类除草剂对玉米安全性及药效。结果表明 :异丙甲草胺与异丙草胺对玉米安全性最高 ,甲草胺次之 ,乙草胺对玉米苗期有药害。田间测产证明异丙甲草胺与异丙草胺对玉米增产明显 ,而乙草胺同人工除草对比略有减产。田间药效表明乙草胺对杂草防除效果最高     

精异丙甲草胺对小麦药害及其安全剂解毒作用初步研究

为了探索精异丙甲草胺在小麦田的应用技术,室内研究了精异丙甲草胺对小麦的安全性,对安全剂进行筛选,并对安全剂作用机制进行初步研究。结果表明,精异丙甲草胺对小麦的生长抑制作用随着土壤含水量增大及温度的下降而上升。对4种安全剂进行筛选,结果表明,解草酮0.5、5g/kg种子处理能够显著降低精异丙甲草胺对小麦的药害,解草啶、二氯丙烯胺、苯叉酰胺在低剂量下能够一定程度缓解精异丙甲草胺药害,但高剂量无缓解作用。进一步研究表明,解草酮0.5~4g/kg种子处理能够有效降低精异丙甲草胺150~600g/hm2(有效成分含量)造成的小麦药害,缓解率均在20%以上,其中1g/kg解草酮种子处理缓解效果最好,提高小麦对精异丙甲草胺的耐药性可达4倍以上。生理指标测定结果表明,解草酮1g/kg种子处理可显著提高小麦出苗期(播后4~6d)GSTs比活力,而GSH含量与对照相当或降低。表明解草酮可能通过提高小麦GSTs活力来增强GSH对精异丙甲草胺的轭合代谢作用,而非通过增加GSH含量来提升精异丙甲草胺降解。     

酿造用高粱土壤处理除草剂筛选

酿造用高粱田土壤处理除草剂种类较少,常用的除草剂配方中多数含有莠去津,筛选不含莠去津且药效较好的除草剂配方,具有较好的实践意义和现实意义。本文选取72%异丙甲草胺乳油、38%莠去津悬浮剂、25%二氯喹啉酸悬浮剂、33%二甲戊灵乳油、48%麦草畏水剂、75%噻吩磺隆水分散颗粒剂、15%硝磺草酮悬浮剂6种除草剂进行混配。通过田间试验进行安全性、除草效果及对高粱产量影响的研究。结果表明,38%莠去津悬浮剂+72%异丙甲草胺乳油、72%异丙甲草胺乳油+48%麦草畏水剂、38%莠去津悬浮剂+48%麦草畏水剂对高粱具有安全性高、除草效果好、提高产量的特点,30 d除草株总防效分别为96.5%、97.4%、93.4%,增产23.9%、23.6%和22.2%。在效益方面,莠去津+异丙甲草胺略高于异丙甲草胺+麦草畏。考虑到莠去津的长残留性及对生态的影响,建议使用72%异丙甲草胺乳油+48%麦草畏水剂。     

The influence of two herbicides on the antifungal activity of some fungicides against Pythium butleri and Rhizoctonia solani causing damping-off of cowpea

The herbicides fluchloralin and alachlor applied to soil altered the effectiveness of fungicide treatments to seed and soil for controlling cowpea damping-off. These herbicides also modified the in-vitro toxicity of the fungicides to the mycelial growth of Pythium butleri and Rhizoctonia solani in a nutrient medium. Both herbicides reduced the toxicity of 2-methoxyethylmercury chloride (MEMC) and propamocarb to the growth of P. butleri, and of carbendazim to the growth of R. solani, but enhanced the toxicity of captafol and quintozene to P. butleri and R. solani, respectively. In pot tests, quintozene gave better control of R. solani damping-off in soil treated with fluchloralin or alachlor than in untreated soil, whereas disease control by carbendazim was decreased in similarly treated soils. Both herbicides attenuated the effectiveness of MEMC and captafol to control the damping-off caused by P. butleri; the efficacy of propamocarb was increased by alachlor but was decreased by fluchloralin. The implications of herbicide-fungicide interactions are discussed in the context of fungicidal control of root diseases in herbicide-treated soil.     

Effect of alachlor on Avena seedlings: Inhibition of growth and interaction with gibberellic acid and indoleacetic acid

The growth of Avena seedlings grown in sand was found to be inhibited by alachlor with the time of onset of inhibition after treatment being a function of herbicide concentration. There was a 12 hr lag period following a subirrigation with 2.5 × 10^?4M alachlor before growth inhibition could be detected. This lag period may be due to uptake and translocation of alachlor from the roots to the site of inhibition or to the exhaustion of certain growth-limiting substance(s) whose biosynthesis is inhibited by alachlor. Additions of gibberellic acid by subirrigation simultaneously with alachlor or after alachlor treatment did not prevent growth inhibition. However, treatment with 10^?3M gibberellic acid 24 hr prior to alachlor treatment overcame the alachlor inhibition. On the other hand, in contrast to gibberellic acid, indoleacetic acid did not prevent inhibition by alachlor.     

Formulation affecting alachlor efficacy and persistence in sandy soils

BACKGROUND: The development of controlled‐release formulations of alachlor to extend the period of weed control was studied. This extended duration reduces the need for high herbicide application rates that could lead to environmental contamination. For this purpose, the influence of formulation, as well as the influence of soil characteristics, on alachlor efficacy and persistence in soil of a commercial formulation (CF) and different ethylcellulose microencapsulated formulations (MEFs) was evaluated. RESULTS: Higher alachlor rates yielded an enhanced initial herbicidal activity. The prolonged release of alachlor provided by the MEFs resulted in a higher herbicidal efficacy and a longer period of weed control compared with the effects of CF in the two soils tested (at 40 days after treatment, oat growth inhibition for CF and MEFs was 1.96% and 93.5% respectively). Soil characteristics strongly influenced alachlor efficacy and weed control by MEFs. The highest alachlor efficacy and persistence were observed in the soil with lowest microbial activity and clay and organic matter content. CONCLUSIONS: The use of MEFs can be advantageous because they permit the maintenance of the desired concentration of the herbicide in the soil for longer periods of weed control. Copyright © 2009 Society of Chemical Industry     

Field experiments for the evaluation of pesticide spray-drift on arable crops

Two distinct approaches were used to characterise spray-drift during the application of atrazine and alachlor to a maize crop. The first consisted in determining the quantities which did not reach their target. A first experiment was carried in 2001 to improve the sampling method. A second experiment in 2002 showed that losses represented 46 and 38% for atrazine and alachlor, respectively. The second approach was to follow the spatiotemporal evolution of the cloud formed during application. The concentrations observed near the application zone during spraying reached 4.5 microg m(-3) for atrazine and 8.5 microg m(-3) for alachlor. With alachlor these concentrations decreased rapidly when increasing distance from the plot or time following treatment, whereas in the case of atrazine they stabilised rapidly (between 0.5 and 0.3 microg m(-3)) both in space and in time. Deposits around the plot were light and slightly higher for alachlor (from 20 to 130 microg m(-2)). Alachlor was more rapidly diluted in space than atrazine, reflecting a differentiated evolution of physical form during the process. Alachlor, being more volatile than atrazine, is quickly transferred to the gaseous phase which was more rapidly dispersed than aerosols.     

Leaching of Alachlor from Alginate-Encapsulated Controlled-Release Formulations

The mobility of alachlor from alginate-encapsulated controlled-release (CR) formulations was investigated in two contrasting soil profiles. Two CR formulations of alachlor were prepared with the following components (1) base—sodium alginate+kaolin+‘Tween’ 20 (1+10+0·5 by mass) and (2) base+40 g kg⁻¹ linseed oil. These were compared to technical grade alachlor and to a commercial alachlor EC formulation (‘Lasso’ 4EC). All herbicide treatments were labeled with [¹⁴C]alachlor and were applied to duplicate soil columns that were composed of a surface and a subsoil horizon. Each horizon was packed to a depth of 12·5 cm, giving a total column length of 25 cm. The columns were leached with 21 cm (420 ml) to 30 cm (600 ml) of 0·01M calcium chloride for a period of 7 to 10 days. Alachlor leaching from the EC formulations was the same as that from the technical material in both soils: 33% in the Evesboro and 10% in the Conover soil. The CR-Oil formulation leached 4 and 2% of the applied [¹⁴C]alachlor, compared to 12 and 3% for the CR-N formulation for the Evesboro and Conover soils, respectively. The CR-Oil formulation also increased the amount of [¹⁴C]alachlor retained in the soil surface horizon (105–114%), compared to CR-N (39–45%), technical material (14–23%) and EC (12–17%).     

甲草胺在水稻上的残留及消解动态

采用气相色谱电子捕获检测(GC-ECD)建立了水稻中除草剂甲草胺的残留分析方法。样品经乙酸乙酯提取,乙二氨基-N-丙基硅烷(PSA)和石墨化炭黑(GCB)净化后采用GC-ECD检测。结果表明:在0.01~1mg/L范围内甲草胺浓度与响应值线性关系良好,相关系数(r)为0.998 8。当甲草胺在水稻植株、稻壳、糙米、田水和土壤中的添加水平为0.01~0.5mg/kg时,平均回收率为79.5%~113.6%,相对标准偏差(RSD)为2.5%~12.7%。甲草胺的最低检出浓度为0.01mg/kg。采用该方法对甲草胺在田间水稻中的消解动态和最终残留进行了测定。甲草胺在稻田植株和田水样品中的消解均符合一级动力学方程。半衰期分别为11.17~26.65d和1.56~1.78d,属于易降解农药。     

Enhanced degradation of some soil-applied herbicides

In a field experiment involving repeated herbicide application, persistence of simazine was not affected by up to three previous doses of the herbicide. With propyzamide, there was a trend to more rapid rates of degradation with increasing number of previous treatments. Persistence of linuron and alachlor was affected only slightly by prior applications. In a laboratory incubation with soil from the field that had received four doses of the appropriate herbicide over a 12–month period, there was again no effect from simazine pretreatments on rates of loss. However, propyzamide, linuron and alachlor all degraded more rapidly in the previously treated than in similar untreated soil samples. Propyzamide, linuron, alachlor and napropamide degradation rates were all enhanced by a single pretreatment of soil in laboratory incubations, whereas degradation rates of isoproturon, metazachlor, atrazine and simazine were the same in pretreated and control soil samples.     

Activity, adsorption and mobility of three acetanilide and two new amide herbicides

Activity, adsorption, and mobility of emulsifiable concentrate (EC) and microencapsulated (ME) formulations of alachlor and acetochlor as well as of metolachlor, S-metolachlor, dimethenamid and flufenacet were studied. Petri-dish bioassay, based on root response of oats ( Avena sativa L.), was used for their activity in sand and in a silty clay loam soil, and for determination of herbicide concentrations in soil solution (not adsorbed) and in column leachates of the adsorption and mobility studies respectively. Flufenacet and both acetochlor formulations showed the highest activity in both soils and ME-alachlor and metolachlor the lowest; the activity of dimethenamid, EC-alachlor and S-metolachlor was intermediate. Activity of both formulations of alachlor and acetochlor decreased with increasing organic matter content, but alachlor activity was reduced more than that of acetochlor. Lower amounts of dimethenamid and S-metolachlor were adsorbed by soil compared with the other herbicides and, consequently, greater amounts of these two herbicides were leached through that soil. None of the herbicides tested was detected below 30 cm. Less alachlor and acetochlor were biologically available in soil solution after their application as ME-formulations and, therefore, lower amounts of both ME-alachlor and ME-acetochlor were leached through the soil compared with those applied as EC-formulations.     

Differential influence of herbicide treatments on activity and kinetic parameters of C4 photosynthetic enzymes from Zea mays

The recommended field dose of rimsulfuron, imazethapyr, alachlor, atrazine or fluometuron differentially reduced shoot fresh and dry weight of 10-day-old maize seedlings as well as leaf protein content during the following 12 days. These reductions seemed consistent during the whole period with fluometuron, atrazine and alachlor but appeared to be nullified by the 5th day of treatment with rimsulfuron and imazethapyr. On the other hand, all herbicides mostly provoked significant inhibitions in specific activities of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31), malate dehydrogenase (MDH, EC 1.1.1.82), pyruvate phosphate dikinase (PPDK, EC 2.7.9.1) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) in leaves during the first 2 days. Thereafter, the inhibition was recovered in samples treated with rimsulfuron and imazethapyr, leveled off with alachlor but consistently augmented with atrazine and fluometuron. The kinetic characterization showed that rimsulfuron or imazethapyr unchanged V_max of all enzymes in vitro, however, V_max of PEPC, PPDK and Rubisco were decreased in vivo. Nevertheless, atrazine or fluometuron substantially reduced V_max of all enzymes while alachlor showed a reduction in this value of PEPC, MDH and Rubisco. Thus atrazine, fluometuron and, to a lower extent, alachlor reduced concentrations of all enzymes as well as rimsulfuron and imazethapyr for only Rubisco. On the contrary, K_m values of all enzymes were progressively increased by all herbicides indicating that the different herbicides altered the structural integrity of all enzymes. These findings conclude that rimsulfuron or imazethapyr competitively inhibited MDH but revealed mixed inhibition to PEPC, PPDK and Rubisco. Atrazine or fluometuron revealed mixed inhibitions to all enzymes whereas alachlor seemed to be either a competitive inhibitor to PPDK or a mixed inhibitor to PEPC, MDH and Rubisco.     

Effects of alachlor on anthocyanin and lignin synthesis in etiolated sorghum (Sorghum bicolor (L.) Moench) mesocotyls

Alachlor, a preemergence herbicide used to control grasses and some broadleaf weeds, was found to inhibit anthocyanin and lignin accumulation in excised sections of mesocotyls from 6 day-old, etiolated sorghum (Sorghum bicolor (L.) Moench) seedlings. Alachlor inhibited anthocyanin and lignin synthesis by 50% at 20 and 28 μM, respectively, with anthocyanin synthesis being inhibited in 1 hr. Other chloroacetanilide herbicides also inhibited anthocyanin synthesis in this system, but all were less active than alachlor. Inhibition of anthocyanin synthesis could not be reversed by compounds from the shikimic acid or phenylpropanoic acid pathways. Anthocyanin synthesis could be restored by removal of alachlor from the incubation solution. Evidence is presented which suggests that alachlor inhibits anthocyanin formation at a point late in the phenylpropanoic acid pathway and not in the shikimic acid pathway.