藜、铁苋菜和苘麻对草甘膦的耐受性及其与莽草酸含量的关系

采用整株生物测定法研究了藜、铁苋菜和苘麻对草甘膦的耐受性,药后14 d测定结果表明,草甘膦对上述3种杂草的ED50分别为215.27、954.34、1 522.54 g a.i./hm~2。通过比较杂草植株地上部莽草酸积累量的变化发现,草甘膦1 230 g a.i./hm~2处理后,藜、铁苋菜和苘麻莽草酸积累量最大值分别为1 400.65、1247.19、581.28μg/g,莽草酸积累量越少的杂草对草甘膦耐受性也越强。药后5 d,对杂草不同部位莽草酸积累量的比较显示,3种杂草顶部叶片莽草酸积累量明显大于根部,敏感种和耐受种相比,顶部叶片莽草酸积累量的差异更为明显,该部位可以准确地评价杂草对草甘膦的耐受程度。     

草甘膦对田旋花和打碗花体内莽草酸含量的影响

草甘膦处理后14d,对田旋花、打碗花、大豆体内莽草酸积累量进行分析,可明确田旋花和打碗花对草甘膦的敏感性.草甘膦840ga.i./hm2、420ga.i./hm2处理后,不同植物体内莽草酸的积累量依次为大豆>打碗花>田旋花.田旋花对草甘膦的耐药能力最强,并且随着生长时间的延长对草甘膦的抗药能力增强.打碗花只是在草甘膦剂量比较低时具有一定的耐药能力.     

田旋花对草甘膦的耐药性机制

在温室条件下,测定了草甘膦对田旋花与打碗花生长的抑制作用及其体内莽草酸含量变化的影响,比较了两者5-烯醇丙酮莽草酸-3-磷酸合成酶（5-enolpyruvylshikimate-3-phosphate syn-thase,EPSPS）基因及编码氨基酸的差异,以探讨田旋花对草甘膦的耐药性机制。结果表明,田旋花对草甘膦的耐药性较高,GR50值（有效成分）为2834.04g/hm2;打碗花相对敏感,GR50值为210.63 g/hm2。经有效成分922.50 g/hm2草甘膦处理后,耐药性高的田旋花体内莽草酸积累缓慢,处理后7天达到峰值,为397.69μg/g;而打碗花体内莽草酸含量呈现持续快速升高的趋势,处理后13天达到峰值,为1 299.52μg/g。克隆获得的田旋花和打碗花编码EPSPS cDNA长度相同,均为1 707 bp,编码520个氨基酸,两者在EPSPS保守区内存在不同的氨基酸位点,田旋花的第101位为极性丝氨酸,而打碗花为非极性苯丙氨酸。     

50%炔苯酰草胺WP防除移栽莴苣田杂草的效果及安全性

50%炔苯酰草胺WP 1 120~2 000 g/hm2对藜、反枝苋、稗、马唐等莴苣田主要一年生杂草具有好的防效,药后40 d鲜重防效达95%以上,对莴苣安全。     

3个草甘膦复配组合对非耕地杂草的防除效果

采用室内盆栽喷雾法和田间茎叶喷雾法,研究草甘膦的复配应用技术。室内测试结果表明:草甘膦与麦草畏配比为(0.5~512)∶1对旱稗和空心莲子草均表现为相加作用;草甘膦与2甲4氯配比为(2.85~5.24)∶1对旱稗和藜均表现为相加作用;草甘膦与草铵膦配比为(0.90~10.32)∶1对旱稗表现为相加作用,对藜表现为增效作用。田间药效结果表明:药后30 d,35%麦草·草甘膦水剂在1 200~1 500 g/hm2剂量下,总草株防效和鲜质量防效分别为93.16%~97.96%和95.24%~99.42%;36%2甲·草甘膦水剂在1 296~2 592 g/hm2剂量下,对总草株防效和鲜质量防效分别为91.09%~94.77%和90.04%~95.07%;36%草甘膦·草铵膦水剂在1 404~2 808 g/hm2剂量下,总草株防效和鲜质量防效分别为92.30%~97.66%和93.08%~97.65%。3个复配剂均能有效防除非耕地杂草,持效期达30 d以上。草甘膦与除草剂复配具有较好的配伍性,与麦草畏、2甲4氯或草铵膦复配均表现为相加或增效作用,室内复配筛选结果与田间药效结果一致。3个复配剂与单剂相比,既增加了药效又提高了速效性。     

20％精喹禾灵乳油防除大豆田杂草的田间试验

采用田间小区试验方法进行20％精喹禾灵乳油防除大豆田一年生禾本科杂草的田间药效试验。结果表明：20％精喹禾灵乳油用药有效成分剂量应为45．0～52．5 g/hm2,该剂量下,20％精喹禾灵乳油搭配笔者单位自主研发的HY-01增效剂,能够有效防除夏大豆田的马唐、牛筋草、稗草;施药后30d,对禾本科杂草的鲜质量防效在95％以上,可见在推荐剂量下施用对大豆安全。     

甲磺隆和草甘膦对空心莲子草乙酰乳酸合酶活性和莽草酸含量的影响

为研究甲磺隆和草甘膦对空心莲子草的作用机理,探索其最佳的使用技术,采用有效成分为30 g/hm2和60 g/hm2 的甲磺隆处理空心莲子草,能明显抑制其茎和根乙酰乳酸合酶的比活性;有效成分为1537.5g/ hm2和3075g/ hm2 的草甘膦处理则能明显抑制空心莲子草莽草酸含量的积累;施用甲磺隆和草甘膦对空心莲子草生长的抑制作用随药剂浓度的提高而增大.二次施用草甘膦(间隔30天)的结果表明,低剂量处理对抑制空心莲子草根组织莽草酸含量的积累更明显.     

环戊噁草酮对直播稻田杂草的室内活性及田间防效评价

为探究环戊噁草酮在直播稻田的科学使用技术,通过室内生物测定,明确了环戊噁草酮的杀草谱、生物活性及对8个主栽水稻品种的安全性,并验证了其在田间的防除效果。室内除草活性测定结果表明,在有效成分225 g/hm2剂量下,环戊噁草酮对牛筋草Eleusine indica、异型莎草Cyperus difformis、鳢肠Eclipta prostrata、香附子Cyperus rotundus及碎米莎草Cyperus iria 5种杂草的鲜重抑制率均可达90%以上,对直播稻田常见杂草稗草、马唐、鳢肠及碎米莎草的GR₅₀值 (有效成分,余同) 在82.15~189.17 g/hm2之间。安全性测定结果表明,在有效成分1800 g/hm2剂量下,环戊噁草酮对8种供试水稻品种安全,株高抑制率为1.89%~5.16%,鲜重抑制率介于1.47%~4.14%之间。环戊噁草酮在隆两优华占、梓两优5号、南粳9108、南粳46这4种水稻与稗草Echinochloa crus-galli、马唐Digitaria sanguinalis、鳢肠、碎米莎草4种杂草间的选择性指数在3.27~28.24之间,其中在水稻与鳢肠、碎米莎草之间的选择性指数明显高于对照药剂噁草酮。田间防效数据表明:在有效成分450 g/hm2剂量下,药后45 d,环戊噁草酮对直播稻田杂草的鲜重防效可达87.94%。研究表明,环戊噁草酮在直播稻田具有良好的应用前景。     

异唑草酮及其混剂噻酮·异唑的除草活性及对玉米的安全性

异噁唑草酮和噻酮·异噁唑是新型?广谱?高活性的土壤处理除草剂?明确异噁唑草酮和噻酮·异噁唑对玉米田杂草的除草活性及对玉米的安全性是该药剂在玉米田应用的重要内容?本文采用温室整株生物测定法研究了两种药剂对玉米田常见杂草的除草活性及对玉米的安全性?结果表明:20%异噁唑草酮悬浮剂和26%噻酮·异噁唑悬浮剂土壤处理对玉米田杂草有较高的除草活性, 两种药剂对各种杂草的GR90均低于田间推荐剂量?20%异噁唑草酮悬浮剂土壤处理对阔叶杂草藜?苘麻?反枝苋和苍耳均有较高的除草活性, GR90均小于54 g/hm 2, 对禾本科杂草狗尾草?马唐?稗和野黍也有较高的除草活性, GR90均小于63 g/hm 2?26%噻酮·异噁唑悬浮剂对阔叶杂草藜?反枝苋?苘麻和苍耳也有较高的除草活性, GR90均小于62 g/hm 2, 对禾本科杂草狗尾草?马唐?稗和野黍也有较高的除草活性, GR90均小于59 g/hm 2?20%异噁唑草酮悬浮剂和26%噻酮·异噁唑悬浮剂土壤处理对玉米的安全性很高, 对玉米和杂草的选择性指数均高于17?异噁唑草酮及其混剂噻酮·异噁唑用药量低?除草活性强?对玉米安全, 是玉米田土壤处理除草剂较为理想的替代产品?     

不同地区田旋花种群对草甘膦耐受水平的差异

在温室条件下,研究了草甘膦对北京、河北等地田旋花种群生长及其莽草酸含量变化的影响。结果表明,不同地区田旋花种群对草甘膦具有普遍的耐受能力,其中河北元氏的田旋花种群对草甘膦的耐受能力最强,GR50值为4 014.92 g a.i./hm2;北京海淀田旋花种群对草甘膦相对敏感,GR50值为957.65 g a.i./hm2。经922.5 ga.i./hm2草甘膦处理后,耐药性最高的河北元氏田旋花种群体内莽草酸含量累积缓慢,处理后14 d所受伤害能自行恢复并保持正常生长;敏感的北京海淀田旋花种群体内莽草酸迅速积累,在处理后7 d莽草酸含量达到最高值,植株生长受到一定程度的抑制。田旋花体内莽草酸含量与其耐药性高低呈负相关,因此可以通过检测田旋花经草甘膦处理后体内莽草酸的含量来明确不同地区田旋花对草甘膦耐受水平的高低。     

赤霉素缓解Mn~(2+)对草甘膦拮抗效应的研究

为探索能够减轻或消除Mn2+对草甘膦拮抗效应的方法,以高羊茅为试材,将赤霉素(GA3)与草甘膦和硫酸锰(Mn2+质量分数为0.1%)混用,研究了赤霉素对Mn2+降低草甘膦药效的缓解作用。结果表明:赤霉素+草甘膦+硫酸锰处理组高羊茅比同剂量草甘膦+硫酸锰处理组叶色更黄,萎蔫更严重,与同剂量草甘膦单剂处理组比较接近,其中加入50 mg/L赤霉素处理组缓解草甘膦拮抗效应的效果最好。赤霉素+草甘膦+硫酸锰处理组高羊茅的干、鲜重及叶绿素含量均低于草甘膦+硫酸锰处理组,而丙二醛和莽草酸含量均明显高于草甘膦+硫酸锰处理组。处理后第6天,赤霉素+草甘膦+硫酸锰组莽草酸含量分别比草甘膦+硫酸锰组增加了49.8%(加入50 mg/L赤霉素)和28.8%(加入30 mg/L赤霉素),差异显著;处理后第2天,赤霉素+草甘膦+硫酸锰组丙二醛含量分别比草甘膦+硫酸锰组增加了54.1%(加入50 mg/L赤霉素)和52.9%(加入30 mg/L赤霉素),差异显著。研究表明,将赤霉素与锰肥和草甘膦混合喷施,将有可能在一定程度上缓解Mn2+对草甘膦的拮抗效应,保证草甘膦的除草效果。     

Rice (Oryza sativa) response to drift rates of glyphosate

Greenhouse and field studies were conducted to investigate response of two rice varieties, Priscilla and Cocodrie, to sub-lethal rates of glyphosate in terms of injury, shikimate accumulation and yield. In the greenhouse, more shikimate accumulated in Cocodrie than Priscilla at comparable glyphosate rates applied to plants at the three-leaf stage. In field studies, glyphosate was applied to both varieties when they were 74-cm tall and in the internode separation growth stage. Visual injury, plant height, and leaf-tissue samples for shikimate analysis were collected at 3, 7, 14, 21 and 28 days after treatment (DAT). Rice yield was also determined. Noticeable visual injury and height reduction to both varieties was observed as early as 7 and 3 DAT in Cocodrie and Priscilla, respectively. Shikimate levels in leaves began to increase in both varieties by 3 DAT in a dose-dependent manner and reached a peak between 7 and 14 DAT. Elevated shikimate levels were still detectable by 28 DAT. Similar levels of shikimate accumulated in both varieties at comparable glyphosate rates. However, glyphosate treatment at comparable rates reduced rice yields more in Cocodrie than in Priscilla. The highest rate of glyphosate reduced yield in Cocodrie by 92% whereas there was only a 60% yield reduction in Priscilla. Shikimate levels in glyphosate-treated rice were strongly correlated to yield reductions across both varieties and appeared to be a better predictor of yield reduction than was visual injury. Visual injury coupled with measured shikimate levels can be used collaboratively to identify glyphosate exposure and estimate subsequent rice yield reductions.     

Response of wild Brassica juncea populations to glyphosate

BACKGROUND: Wild Brassica juncea (L.) is a troublesome arable land weed and ruderal. It is critical to understand the responses of this weed to herbicides, because the assessment of its susceptibility profile has important ecological and evolutionary consequences for future cultivation of herbicide-tolerant oilseed rape. The response of 31 wild populations from different geographic origins in China to glyphosate was evaluated with two bioassay methods, and variable responses were found in initial studies. Dose-response assays were conducted to characterize the extreme populations further, and shikimate accumulation in vivo was determined using a spectrophotometric method. RESULTS: On the basis of ID(50) values, the resistance ratios (R/S) were 5.85 and 4.19 for two glyphosate-resistant B. juncea populations in germination tests, whereas they were 4 times more resistant to glyphosate in spray tests. There were differences in shikimate accumulation patterns between the two biotypes. Shikimate concentrations in resistant populations began to decline from 6 days after treatment (DAT), while they increased continually in susceptible populations. CONCLUSION: The results obtained suggest that the populations responded differentially to glyphosate, and this variability may provide the genetic basis for evolution of individuals with increased resistance to glyphosate, with important implications for herbicide resistance management, especially in the context of risk assessment of glyphosate-tolerant crops.     

Shikimate accumulation in nine weedy species following glyphosate application

Glyphosate is commonly used in a variety of weed control scenarios and plants respond biochemically by continuing to attempt to push carbon through the shikimate pathway. The result is an accumulation of shikimate in sensitive plants in the days immediately after application. This research determined shikimate accumulation dynamics in nine problematic plant species from 0 to 6 days after treatment (DAT). Ambrosia artemisiifolia, Trifolium repens and Conyza canadensis showed rising concentrations through 6 DAT to >4000 mg L^?1. Chenopodium album, Xanthium strumarium and Urochloa platyphylla showed concentrations levelling off to a constant of about 2000 mg L^?1. Ambrosia trifida, Amaranthus palmeri and Polygonum pensylvanicum generally showed lower levels of shikimate accumulation and concentrations were decreasing after 3 DAT. No apparent relationships were evident between shikimate accumulation pattern and plant growth rate or speed of glyphosate activity. There also appeared to be no pattern in the shikimate accumulation trends that would allow for an informed decision as to which of these species would be most likely to develop glyphosate resistance. Shikimate concentrations were in agreement between field and glasshouse conditions for C. canadensis, but did not agree with those from A. palmeri.     

Resistance to glyphosate in Lolium rigidum

Annual ryegrass (Lolium rigidum) is a widespread and important weed of Australia and populations of this weed have developed resistance to most major herbicides, including glyphosate. The possible mechanisms of resistance have been examined in one glyphosate-resistant Lolium population. No major differences were observed between resistant and susceptible biotypes in respect of (i) the target enzyme (EPSP synthase), (ii) DAHP synthase, the first enzyme of the target (shikimate) pathway, (iii) absorption of glyphosate, or (iv) translocation. Following treatment with glyphosate, there was greater accumulation of shikimate (derived from shikimate-3-Pi) in susceptible than in resistant plants. In addition, the resistant population exhibited cross-resistance to 2-hydroxy-3-(1,2,4-triazol-1-yl)propyl phosphonate, a herbicide which, although structurally similar to glyphosate, acts at an unrelated target site. On the basis of these observations we speculate that movement of glyphosate to its site of action in the plastid is involved in the resistance mechanism. © 1999 Society of Chemical Industry     

高锰胁迫下草甘膦对空心莲子草体内莽草酸含量和抗氧化酶活性的影响

鉴于高锰胁迫下空心莲子草Alternanthera philoxeroides对草甘膦的耐药性增强,在水培条件下研究了不同浓度锰条件下草甘膦处理后该草体内莽草酸的积累和主要抗氧化酶系统的响应。次高浓度锰(0.31 mmol/L)条件下培养120 d后空心莲子草体内过氧化氢酶(CAT)活性显著高于常规浓度锰处理(0.009 1 mmol/L,对照);高浓度锰(2.45 mmol/L)条件下超氧化物歧化酶(SOD)活性升高,CAT活性下降。草甘膦(按草甘膦酸68 g/hm2)茎叶处理后6 d内,常规锰浓度培养的空心莲子草体内莽草酸含量比用草甘膦刚处理时增加了31.9％~226.0%,且显著高于同一时间次高锰和高锰的处理;不同锰浓度下培养的空心莲子草体内过氧化物酶(POD)和CAT、SOD活性均为先升高后再逐渐下降,但次高锰处理的该3种酶活性均高于对照,高锰处理的SOD和POD活性高于对照,而CAT活性与对照相当。上述结果表明,在较高锰浓度下空心莲子草能启动抗氧化酶系统而能有效地清除自由基;在草甘膦处理后初期,高锰条件下空心莲子草体内莽草酸途径受抑制程度较轻,抗氧化酶活性较高,这可能是空心莲子草耐高锰和高锰条件下该草耐草甘膦的部分机制。     

Low doses of glyphosate change the responses of soyabean to subsequent glyphosate treatments

Many herbicides promote plant growth at doses well below the recommended application rate (hormesis). The objectives of this study were to evaluate glyphosate‐induced hormesis in soyabean (Glycine max) and determine whether pre‐treating soyabean seedlings with low doses of glyphosate would affect their response to subsequent glyphosate treatments. Seven doses (1.8–720 g a.e. ha^?1) of glyphosate were applied to 3‐week‐old seedlings, and the effects on the electron transport rate (ETR), metabolite (shikimate, benzoate, salicylate, AMPA, phenylalanine, tyrosine and tryptophan) levels and dry weight were determined. The lowest dose stimulated ETR and increased biomass the most. Benzoate levels increased 203% with 3.6 g a.e. ha^?1 glyphosate. Salicylate content and tyrosine content were unaffected, whereas phenylalanine and tryptophan levels were increased by 60 and 80%, respectively, at 7.2 g a.e. ha^?1. Dose–response curves for these three amino acids were typical for hormesis. In another experiment that was replicated twice, soyabean plants were pre‐treated with low doses of glyphosate (1.8, 3.6 or 7.2 g a.e. ha^?1) and treated with a second application of glyphosate (1.8, 3.6, 7.2, 36, 180 or 720 g a.e. ha^?1) 14 days later. For total seedling dry weight, a 3.6 and 7.2 g a.e. ha^?1 glyphosate dose preconditioned the soyabean seedlings to have greater growth stimulation by a later glyphosate treatment than plants with no preconditioning glyphosate exposure. Optimal hormetic doses were generally higher with pre‐treated plants than plants that had not been exposed to glyphosate. Thus, pre‐exposure to low doses of glyphosate can change the hormetic response to later low‐dose exposures.     

草甘膦铵盐对3种滩涂动物抗氧化酶、丙二醛及大弹涂鱼红细胞微核的影响

为评价草甘膦对河口及滩涂水域生物的影响,采用室内人工染毒法,研究了草甘膦铵盐对可口革囊星虫Phascolosoma esculenta、缢蛏Sinonovacula constricta Lamark和大弹涂鱼Boleophthalmus pectinirostris 3种滩涂动物超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)、丙二醛 (MDA) 及大弹涂鱼红细胞微核的影响。结果表明:经低浓度 (63.5 mg/L) 草甘膦短时间 (2 d) 染毒后,可口革囊星虫肠组织的SOD、CAT活性值及MDA含量分别为231.54、1.719 U/mg pro. 和0.60 nmol/mg pro.,3种指标均显著或极显著高于相应对照值 (204.88、1.521 U/mg pro. 和0.54 nmol/mg pro.),且随着药剂处理浓度增加,SOD、CAT活性及MDA含量均升高;但当染毒时间延长至8 d时,可口革囊星虫肠组织的SOD、CAT活性值及MDA含量均明显降低,分别为155.67、1.403 U/mg pro. 和0.53 nmol/mg pro.,显著低于对照,且随药剂处理浓度进一步增加,酶活性及MDA含量值降低更显著。草甘膦对缢蛏内脏团及大弹涂鱼肝脏SOD、CAT活性及MDA含量的影响表现出类似规律。此外,经低浓度 (53.5 mg/L) 草甘膦染毒8 d后,大弹涂鱼红细胞微核率及核异常率分别为17.00‰ 和21.33‰,均极显著高于相应对照值 (13.67‰ 和13.33‰),且随着草甘膦浓度增大,其红细胞微核率及核异常率均显著升高,表明大弹涂鱼对草甘膦有较高的敏感性。所得研究结果可为评价草甘膦对河口及滩涂水域生物的影响提供参考依据。     

有机硅喷雾助剂对草甘膦在空心莲子草上的沉积和生物活性的影响

研究了有机硅喷雾助剂(OSA)对草甘膦在空心莲子草Alternanthera philoxeroides上的沉 积与生物活性的影响。当采用较大喷雾雾滴,施药液量高于632.5 L/hm2时,添加OSA(0.35 g/L) 后,草甘膦药液在空心莲子草上的沉积量显著下降。最大稳定持留量(MRG)由未添加OSA的0.61~0.63 μ L/cm2下降到0.50~0.54 μ L/cm2。分别以33.7和67.4 μ g/株剂量的草甘膦点叶处理空心莲子草,发现添加OSA的处理对再生植株茎叶生长的抑制率分别比对照提高了8.89%和14.83%。草甘膦(有效成分199.3 g/hm2)施药后1 h进行人工模拟降雨处理,添加OSA后药剂对空心莲子草的生物活性比无OSA对照处理提高了20.5%。研究结果表明,添加有机硅喷雾助剂促进了草甘膦在空心莲子草中的向下传导性能,提高了草甘膦水剂在空心莲子草叶片的耐雨水冲刷性能,但会降低草甘膦药液在空心莲子草上的最大稳定持留量。     

Metabolic effects in rapeseed (Brassica napus L.) seedlings after root exposure to glyphosate

Metabolic effects in rapeseed (Brassica napus L.) seedlings after root exposure to sublethal concentrations of glyphosate were examined in order to evaluate the possibilities of using a response pattern in plants as a measure of exposure to glyphosate through the growth media, more sensitive than the well-known biomarker shikimate. Rapeseed seedlings were grown in hydroponic nutrient solutions containing varying sublethal concentrations of glyphosate (1–50 μM). After 9 days of glyphosate exposure, the shoots of the seedlings were analysed with respect to the effects on selected metabolites downstream from the primary affected metabolite shikimate, which accumulated linearly in response to glyphosate exposure (from 0 to ∼126 μmol/g DW). The selected metabolites analysed, comprising the free amino acids, and the glucosinolates derived therefrom, showed complex patterns in response to glyphosate exposure. Most noteworthy was though that they responded at the lowest concentrations of exposure to glyphosate (1 μM), where no visual effects, decrease in shoot DW or shikimate could be detected, indicating that a biomarker response more sensitive than that of shikimate can be established for plants exposed to glyphosate.