Longevity of seeds of four annual grass and two dicotyledon weed species as related to placement in the soil and straw disposal technique

Persistence of seeds of the four winter annual grass species, Alopecurus myosuroides , Bromus sterilis , Bromus hordeaceus and Vulpia myuros , were studied under field conditions. The studies also included the two dicotyledon species, Tripleurospermum inodorum and Galium aparine . Seed samples were stored in the field at different depths in the plough layer for a year. Following germination, seedling emergence was taken as an indicator of field persistence. In a supplementary investigation, seed samples were placed on the soil surface or buried at 2 cm for a month and then tested for viability. Persistence of the two Bromus species was very short, irrespective of depth and duration of burial. Persistence of the other species was positively correlated with incorporation of seeds to a few centimetres depth. Increasing the depth of incorporation below 2 cm had a variable influence on persistence. Persistence of seeds placed directly on the soil surface was short, whether they were left there for a year or a month. Whether seeds at the soil surface were left uncovered or covered with chopped straw had limited influence on seed persistence. However, straw cover significantly increased persistence of A. myosuroides seeds and there was the same tendency with T. inodorum .     

不同供氮水平多花黑麦草化感抑草作用与资源竞争分析

[目的]为了判断黑麦草与猪殃殃的化感作用与资源竞争关系。[方法]运用化感一竞争分离法,通过盆栽混播不同比例的供、受体植株,测定受体植株干重的变化规律,以探讨黑麦草对猪殃殃杂草的化感作用或资源竞争的关系。[结果]当黑麦草和猪殃殃混播比例较大时（供受体混播比例为12：10）,会由竞争作用转为化感作用;而在氮素胁迫条件下,两者的关系均会加强,在氮水平为10kg／667m2时,化感作用最强,随着氮水平的加大,抑制作用减弱,竞争作用逐渐加强。[结论]明确黑麦草与猪殃殃的资源竞争与化感作用的关系,为黑麦草化感抑草作用研究提供理论依据。     

Influence of alkyl oleates on efficacy of phenmedipham applied as an acetone:water solution on Galium aparine

Galium aparine plants were treated at the two-whorl stage with technical-grade phenmedipham. The active ingredient was applied at 10 doses as an acetone:water solution, without emulsifier, alone or in mixture with an ester of oleic acid (methyl, butyl, octyl, dodecanyl, octadecanyl). The plant response was described by a log-logistic regression model. Phenmedipham applied alone did not kill the plants even at the highest dose (1621 g a.i. ha⁻¹). In contrast, addition of any alkyl oleate to phenmedipham killed the plants at the 200–400 g a.i. ha⁻¹ doses. The alkyl oleates differently affected activity of phenmedipham. Their effects could be ranked as follows: butyl ≥ methyl; octyl> methyl; dodecanyl ≤ methyl; octadecanyl < methyl oleate. Thus, butyl and octyl oleate promoted phenmedipham activity more than methyl oleate.     

几种除草剂混配对麦田阔叶杂草的防除效果

通过田间试验,比较双氟磺草胺、唑草酮、氯氟吡氧乙酸异辛酯等9种除草剂及其混剂在小麦田防除播娘蒿、猪殃殃、荠菜3种阔叶杂草的效果,以期筛选出对河南省小麦田优势阔叶杂草防效较好的药剂组合。结果表明,供试药剂对小麦均比较安全,对小麦生长发育无不良影响。药后28 d,29%氯氟吡氧乙酸异辛酯WP 111.31 g/hm~2(有效成分用量,下同)+5%唑草酮WP 3.31 g/hm~2对播娘蒿和猪殃殃的防效最佳,其中对播娘蒿的株防效和鲜质量防效均达到100.00%,对猪殃殃的株防效和鲜质量防效分别为68.42%、71.44%;50 g/L双氟磺草胺SC 7.50 g/hm~2+40%唑草酮WG 15.00 g/hm~2+200 g/L氯氟吡氧乙酸异辛酯EC 120.00 g/hm~2对荠菜的防效最佳,株防效为80.69%,鲜质量防效为85.92%。29%氯氟吡氧乙酸异辛酯WP 111.31 g/hm~2+5%唑草酮WP3.31 g/hm~2对总草的防效最佳,株防效为82.80%,鲜质量防效为89.49%;50 g/L双氟磺草胺SC7.50 g/hm~2+90%甲基碘磺隆钠盐TG 9.99 g/hm~2复配和200 g/L氯氟吡氧乙酸异辛酯EC 150.00 g/hm~2对总草的株防效分别为60.24%、47.31%,鲜质量防效分别为66.86%、53.92%,效果较差。总体来说,推荐使用29%氯氟吡氧乙酸异辛酯WP 111.31 g/hm~2+5%唑草酮WP 3.31 g/hm~2、50 g/L双氟磺草胺SC 7.50 g/hm~2+40%唑草酮WG 15.00 g/hm~2,不仅对小麦田播娘蒿、荠菜、猪殃殃均有较好的防效,而且对小麦安全。     

多花黑麦草根系抑草潜力评价及其化感物质分析

以我国南方种植较普遍的多花黑麦草‘美克斯’和‘海克里斯’为供体试验材料,以杂草猪殃殃为受体材料,探讨多花黑麦草根系浸提液的化感潜力及分析主要化感物质成分(GC-MS鉴定)。结果表明,2个多花黑麦草根系浸提液对猪殃殃具有化感抑制作用,对种子发芽率大小的影响与质量分数呈负相关,随着质量分数的增加,抑制作用加强;美克斯对猪殃殃种子发芽率的抑制作用要强于海克里斯,美克斯对受体种子发芽抑制率为-0.55,海克里斯的为-0.51;2个多花黑麦草根系浸提液对猪殃殃幼苗生长也存在明显的抑制作用,表现为随着质量分数的增加抑制作用加强,在10.0%时的综合抑制率最高,其次为7.5%,再次为5.0%;相同质量分数下不同品种间以美克斯的抑制作用要强于海克里斯;美克斯根系浸提液中的化感物质包括12类,与抑制作用相关的酚酸类物质占主要成分,包括苯酚类和酸类物质。海克里斯根系分泌的化感物质中,脂肪族化合物占主要成分,包括草酸、甲醇、乙醇和丁醇类。     

山东省冬小麦田猪殃殃抗药性水平及ASL靶标抗性机理分析

为明确山东省冬小麦田猪殃殃Galium aparine对常规除草剂氯氟吡氧乙酸、苯磺隆及双氟磺草胺的抗性水平和抗性种群的乙酰乳酸合成酶(acetolactate synthase,ALS)靶标抗性机理,在温室内采用整株生物测定法测定21个猪殃殃种群对氯氟吡氧乙酸、苯磺隆和双氟磺草胺的抗性水平,同时根据猪殃殃ALS基因序列设计引物,提取猪殃殃高抗种群单株基因组DNA进行测序,并与拟南芥Arabidopsis thaliana敏感型ALS基因进行比对,查找突变位点分析其抗性机理。结果表明,21个猪殃殃种群对氯氟吡氧乙酸均敏感,尚未产生抗性;90.48%的猪殃殃种群已对苯磺隆产生了抗性,其中低抗、中抗和高抗种群分别占总种群数的23.81%、23.81%和42.86%,相对抗性指数最高为1 134.82;71.43%的猪殃殃种群已对双氟磺草胺产生了抗性,其中低抗、中抗和高抗种群分别占总种群数的19.05%、9.52%和38.10%,相对抗性指数最高为87.05。高抗苯磺隆种群XZ-1和LW均发生了ALS基因第197位氨基酸功能位点的突变,其中XZ-1种群发生了CCC(脯氨酸)到TCC(丝氨酸)...     

麦田抗性生物型猪殃殃对苯磺隆的抗性机制

为探讨猪殃殃Galium aparine抗药性生物型(R)对苯磺隆的抗性机制,测定了苯磺隆对猪殃殃抗性、敏感(S)生物型体内靶标酶 、代谢酶 及抗氧化酶 影响的差异。离体试验结果表明,苯磺隆对R、S生物型猪殃殃ALS的抑制中量(IC50)分别为0.682、0.718 μg/L(有效剂量),R、S生物型猪殃殃ALS对苯磺隆的敏感性不存在差异。活体试验结果表明,苯磺隆茎叶喷雾处理后,R、S生物型ALS活力均表现为先上升,但S生物型上升幅度小,且随后快速下降,第3 d即回落至对照之下,并维持在低于对照的水平,而R生物型ALS活力在第2 d可达对照的4.10倍,第5 d 基本回落至对照水平,之后基本维持在对照水平;R生物型GSTs活力在第1 d即开始上升,最高可达对照的 2.40 倍,而S生物型则表现为先下降,然后小幅回升,最高为对照的1.61倍,两者在10 d左右均回落至对照水平;R生物型SOD活力与对照基本相同,而S生物型虽略有下降,但R、S间不存在显著差异;两者POD活力虽均有大幅提高,但亦不存在显著差异。结果表明,低水平抗药性生物型猪殃殃对苯磺隆产生抗性的原因可能是ALS过量表达及GSTs对苯磺隆的代谢作用加强,而不是由于ALS的敏感性下降,同时POD、SOD在减轻药害中也具有一定作用。     

猪殃殃对AHAS抑制剂靶标抗性的快速分子检测

为建立猪殃殃靶标抗性快速检测方法,并明确小麦田猪殃殃Galium aparine var.tenerum对AHAS抑制剂靶标的突变类型及分布,从河南、陕西、安徽、江苏和山东5省不同田块采集疑似对AHAS抑制剂产生抗性的猪殃殃植株,采用特异性引物PCR扩增靶标酶AHAS基因保守区片段,并以直接测序法检测采集样品,通过与拟南芥AHAS基因序列比对分析后明确其突变位点。结果显示,在5省25个农田的样品中共有19个农田检测到AHAS突变,分布在河南、安徽和江苏3省;在检测样品中发现突变发生在2个位点,共有3种突变类型,分别是197位脯氨酸(CCC)突变为丙氨酸(GCC)或丝氨酸(TCC),或者是574位色氨酸(TGG)突变为亮氨酸(TTG),检测结果与田间药效反应基本一致。这种用特异性引物扩增目的片段测序的方法,由于其可以在生长当季进行检测,适用于田间靶标突变抗性猪殃殃的快速检测与监测。     

中国北方部分冬麦区猪殃殃对苯磺隆的抗性水平

采用温室盆栽法和培养皿法分别测定7省14个县市14块麦田的猪殃殃潜在抗药性生物型和临近非耕地敏感生物型对苯磺隆的抗性水平。温室盆栽法试验结果表明,除河北省石家庄、山西省太原、陕西省周至、山东省泰安采集点麦田猪殃殃生物型对苯磺隆仍处于敏感状态外,其它地区麦田猪殃殃均产生了不同程度的抗药性,抗性倍数在1.6～4.3之间,其中河南省许昌采集点抗药性最高,达4.3倍,安徽省太和、陕西省华县采集点抗药性最低,抗性倍数均为1.6;培养皿法试验结果表明,河南省许昌采集点抗药性较高,抗性倍数为2.2,而安徽省太和、陕西省华县采集点抗药性较低,抗性倍数分别为1.9和1.7。两种方法的抗性趋势基本一致。