银胶菊花对苘麻和稗的化感作用

通过室内培养皿法,研究了银胶菊花水浸提液及其乙酸乙酯相、正丁醇相、剩余水相不同极性组分对苘麻和稗种子萌发及幼苗生长的影响。定性测定结果表明,在50 g/L浓度处理下,水浸提液完全抑制苘麻和稗种子萌发,对苘麻和稗根长、芽长、鲜重抑制率分别为82.6%、89.1%、84.3%和91.7%、55.8%、39.1%;正丁醇相抑制苘麻种子萌发和幼苗生长最强,乙酸乙酯相抑制稗种子萌发和幼苗生长最强。定量测定结果表明,在1 g/L浓度处理下,乙酸乙酯相生物活性最高,苘麻和稗种子萌发率分别为13.3%和33.3%,对苘麻和稗根长、芽长、鲜重的抑制率分别为63.1%、80.0%、58.3%和51.3%、26.7%、23.3%。     

银胶菊对苘麻化感作用初步研究

通过室内培养皿法,研究了银胶菊水浸提液对苘麻种子萌发和幼苗生长的影响.结果表明,根、茎、叶、花水浸提液的化感作用强度存在差异,花、叶水浸提液对苘麻的化感抑制强度高于根、茎,且抑制强度随处理浓度的升高而增强;在20％浓度下,花、叶水浸提液完全抑制苘麻幼苗生长,对苘麻种子萌发的抑制率分别为91.9％、78.4％.     

银胶菊的花与叶对苘麻化感作用联合测定

运用室内培养皿生物测定法对银胶菊(Parthenium hysterophorus L.)花、叶水浸提液乙酸乙酯相化感作用联合测定发现,混配物抑制苘麻胚轴的生长,但混配物并未表现出化感抑制作用的增效效应,这表明二者之间的化感物质是相互独立起作用的.     

银胶菊的花对稗草的化感作用及其化感物质分离与鉴定

为明确银胶菊的花组织对稗草的化感作用及其活性物质成分,采用培养皿法和室内盆栽法,研究了其水浸提液的乙酸乙酯相、正丁醇相和剩余水相对稗草生长的影响。结果表明,乙酸乙酯相的化感抑制活性最高,其中,温室盆栽试验中对稗草萌发、株高、鲜重的抑制率分别为11.1%、10.2%和14.6%。采用GC-MS技术,从乙酸乙酯相较高活性组分中分离鉴定了15种主要化合物,分别为烃类及其衍生物、萘类、醇类、苯类、酸类、酮类和酯类。     

银胶菊植株水浸提液对几种植物的化感作用

以萝卜、黄瓜、三叶鬼针草和马唐4种植物的种子为供试对象,测定了银胶菊植株水浸提液的化感活性.结果表明:(1)低浓度(0.01 g/ml)的银胶菊植株水浸提液对萝卜和黄瓜种子的萌发没有影响,相对萌发率均为100%,而对萝卜和黄瓜幼苗的生长却表现为促进作用,相对苗长分别为174.3%和103.9%,相对根长分别为151.9%和103.9%;(2)高浓度(0.5 g/ml)的银胶菊植株水浸提液对萝卜和黄瓜的种子萌发率、幼苗根长和苗高均表现为抑制作用,并随着浓度的提高,抑制作用增强;(3)不同浓度的银胶菊植株水浸提液对三叶鬼针草和马唐的种子萌发率、幼苗根长和苗高均表现为抑制作用,并随着浓度的提高,抑制作用增强.其中,当水浸提液浓度为0.5 g/ml时,三叶鬼针草和马唐的种子相对萌发率为0,受到强烈的化感作用.     

银胶菊的花对小麦的化感作用机制

采用温室盆栽法,研究了银胶菊的花水浸提液对小麦生长及其生理生化机制的影响,以明确其对小麦的化感作用。结果显示,花水浸提液抑制小麦种子萌发和幼苗生长,且抑制强度随浸提液浓度的升高而加强;随着花水浸提液浓度的增加,小麦叶片光合作用、光合色素含量和过氧化氢酶(CAT)活性下降,磷(P)和丙二醛(MDA)含量升高,氮(N)含量呈现先降低后趋于正常的变化趋势,硝酸还原酶(NR)活性呈现先降低后升高的变化趋势,谷氨酰胺合成酶(GS)活性没有显著变化,而过氧化物酶(POD)和超氧化物歧化酶(SOD)活性则呈现先升高后降低的变化趋势。表明银胶菊的花水浸提液抑制小麦叶片光合作用,提高了小麦叶片的MDA含量,并降低了小麦叶片SOD、POD和CAT的活性。     

白三叶草对苘麻和稗草的化感作用

为进一步明确白三叶草对杂草的化感作用，研究了不同浓度的白三叶草地上部分水浸液和根部水浸液对苘麻和稗草种子发芽率和种子萌发过程中生理生化机制的影响。结果表明，白三叶草地上部分水浸液和根部水浸液显著抑制苘麻和稗草种子的发芽率，降低了杂草种子萌发过程中超氧化物歧化酶、过氧化氢酶的活性，抑制了杂草种子萌发过程中的呼吸速率、根系活力，明显提高了杂草种子过氧化物酶活性和丙二醛的含量。用浓度0．1g／mL的地上部分水浸液处理稗草种子后，最终发芽率降低56％，稗草种子萌发过程中超氧化物歧化酶、过氧化氢酶的活性分别降低24．78％、48．69％，呼吸速率和根系活力分别降低40．63％、36．28％，过氧化物酶活性和丙二醛的含量分别提高32．30％、87．40％。随着水浸液浓度的提高，化感作用增强，地上部分水浸液对杂草的化感作用大于根部水浸液，对稗草的抑制作用大于苘麻的化感作用。     

油菜对千金子的化感作用及其化感物质分离鉴定

研究了油菜茎根水提液对后茬稻田中恶性杂草千金子的化感作用,并分离鉴定了化感物质。结果表明,不同品种油菜的水提液对千金子种子萌发有抑制作用,对幼苗生长无影响,同时对水稻种子萌发及幼苗生长安全。利用室内生测及GC-MS方法鉴定抑制千金子种子萌发的化感物质为有机酸,抑制率达100%。其主要成分为油酸、棕榈酸、芥酸、亚油酸、硬脂酸、二十碳烯酸及山嵛酸。     

三裂叶蟛蜞菊对绿豆的化感作用

研究了三裂叶蟛蜞菊各器官水提液对绿豆种子萌发及其幼苗生长的影响。结果表明,各器官水提液浸种能显著降低绿豆种子发芽率,且发芽率随水提液浓度增大而降低;各器官水提液能显著抑制绿豆幼苗的生长,5d后绿豆平均根长随水提液浓度增大而变短;对绿豆种子萌发的化感作用从强到弱依次为茎〉叶〉全株〉根。     

核桃叶水浸液对四种作物的化感作用

研究了核桃叶水浸液对玉米、花生、豌豆和辣椒种子萌发及幼苗生长的化感作用.结果表明,不同浓度核桃叶水浸液对4种作物各项测定指标抑制作用各异,随着处理浓度增大,抑制作用不断增强,其中对4种受体发芽势和根长的抑制效应与对照相比差异显著;随处理浓度降低,抑制作用减弱,在0.025g/mL处理时甚至表现为促进作用,体现出双重浓度...     

Glyphosate efficacy is contributed by its tissue concentration and sensitivity in velvetleaf (Abutilon theophrasti)

Glyphosate efficacy was examined in young velvetleaf plants from the standpoint of its tissue distribution and sensitivity. In whole plant assays, manual application of a sub-lethal dose to the first leaf resulted only in meristem injury while other tissues remained visually healthy. Our studies showed that this differential tissue response was caused by a combination of differential distribution as well as sensitivity to glyphosate. Using [¹⁴C]glyphosate, we measured tissue injury and glyphosate residue, and calculated tissue threshold for 50% growth inhibition. Our studies showed that roots and meristem have high glyphosate distribution (45 and 34% of translocated, respectively) and low inhibition thresholds (0.23 and 0.21 ppm, respectively) resulting in tissues that were easily killed by glyphosate. In contrast, the base stem contained a much higher inhibition threshold (8.4 ppm) with only intermediate distribution (10%) resulting in a tissue that was most difficult to kill. We observed a linear relationship between glyphosate dose and tissue concentration; furthermore, tissue distribution pattern was independent of dose or surfactants class. At a sub-lethal dose, sensitive tissues that received a large distribution of glyphosate were preferentially killed. As the dose was increased, more glyphosate was available for distribution, and all tissues received a proportionately greater amount of glyphosate. Plant death occurred when the applied dose was sufficient to attain the lethal threshold in all tissues.     

狭卵链格孢菌毒素细交链孢菌酮酸对稗草细胞膜脂质过氧化作用的影响

为明确狭卵链格孢菌Alternaria augustiovoide菌株AAEC05-3产生的毒素细交链孢菌酮酸(tenuazonic acid,TeA)的作用机制,利用离体试验,研究了TeA对稗草叶片细胞膜脂质过氧化的影响。结果显示,低浓度TeA处理对稗草叶片的细胞膜透性和脂质过氧化影响不大;用高浓度TeA处理稗草叶片24 h后,稗草叶片细胞膜透性和脂质过氧化作用显著增强。TeA浓度为100 μmol/L时,稗草叶片相对电导率和丙二醛(MDA)含量分别增加28.21%和63.58%;脂氧合酶(Lox)活性增高61.59%,且不饱和脂肪酸含量显著降低,亚油酸(18∶2)和亚麻酸(18∶3)分别降低19.56%和17.20%,脂肪酸氢过氧化物在叶片中大量积累。表明TeA可以诱导稗草叶片细胞膜的脂质过氧化作用。     

Biotransformation of clomazone in rice (Oryza sativa) and early watergrass (Echinochloa oryzoides)

Rice (Oryza sativa), a relatively tolerant species, and early watergrass (Echinochloa oryzoides; EWG), a relatively susceptible species, were exposed to ¹⁴C-labeled clomazone to determine accumulation, biotransformation, and mass balance. On a total mass basis, rice absorbed more clomazone than EWG (p < 0.05), but on a nmol/g basis, there was no significant difference between the two species (p > 0.05). Rice contained more extractable ¹⁴C residues (7.7 ± 0.5 vs. 4.8 ± 0.5 nmol in rice vs. EWG, respectively; p < 0.5), but the concentration in EWG was significantly higher (4.2 ± 0.5 vs. 1.8 ± 0.1 nmol/g in EWG vs. rice, respectively; p < 0.01). More metabolized residue was measured in EWG compared to rice (84.1% vs. 67.9%; p < 0.01). Both species produced hydroxylated forms, β-d-glucoside conjugates, and several other unidentified polar metabolites, but EWG generally produced higher metabolite concentrations. The concentration of the suspected active metabolite, 5-ketoclomazone, was significantly higher in EWG vs. rice (21 ± 2 vs. 5.7 ± 0.5 pmol/g, respectively; p < 0.01). Differences in sensitivity to clomazone between rice and EWG appear to be due to differential metabolism, but in this case the more susceptible EWG qualitatively and quantitatively metabolized more clomazone than the more tolerant rice. This is consistent with the action of a metabolically activated herbicide. This metabolic difference could be exploited to develop herbicide safeners for use with clomazone.     

多炔类化合物对稗草光活化生长抑制活性及作用靶标

采用小杯法测定了8个人工合成的多炔类化合物对稗草的光活化生长抑制活性,经近紫外光(320～400nm)照射后,所测的化合物中的化合物5(1-苯基-4-(3,4-亚甲基二氧)苯基-丁二炔)能显著抑制稗草根、茎的伸长,当处理浓度为100mg/L时,经光照处理测得对稗草根、茎生长抑制率分别为93.56%和68.03%,而非光照处理则为27.73%和17.76%,显示出明显的光活化生长抑制效应.在检测不同光照时间和不同浓度处理的试验结果中发现,随着光照时间从0.5h到3h,浓度从0.1mg/L到10mg/L时,测得稗草根长和茎长的抑制率呈现明显的正相关.电镜下观察表明,经化合物5处理的稗草愈伤组织,浓度为10mg/L、光照为3h时,可造成生物膜结构的破坏,而非光照的细胞内膜结构受到轻度的损伤.     

稗草生防菌新月弯孢菌Culvularia lunata菌株J15(2)的安全性和致病力

为了确定生防菌新月弯孢菌Culvularia lunata菌株J15(2)的安全性及防除稗草的潜力,研究了该菌株的寄主范围,接种孢子时稗草叶龄、接种后保湿时间、接种浓度对该菌株致病力的影响,土壤带菌对稗草出苗的影响,以及与化学除草剂的相互作用.结果显示,菌株J15(2)只能在稗草上侵染并扩展;接种孢子后保湿24 h,对2叶期稗草抑制率可达55.6%,对1.5叶期稗草抑制率可达100%;保&48h,对2叶期稗草防效提高至91.6%;接种孢子量需达1012孢子/hm2才能较好地抑制稗草生长;土壤带菌亦可抑制稗草生长.该菌与化学除草剂精噁唑禾草灵或二氯喹啉酸混用能显著提高除稗效果,菌株J15(2) 3.3 × 1012孢子//hm2分别与精噁唑禾草灵有效剂量3.83g/hm2二氯喹啉酸有效剂量250.00g/hm2混用,对稗草防效分别为99.5%和88.6%,远高于这两个除草剂单用时的药效.该试验结果表明,菌株J15(2)具有作为微生物除草剂的开发潜力.