草甘膦、草铵膦喷施对槟榔根系形态及生理的影响

除草剂防除杂草的同时会给非靶标作物带来药害,频繁使用除草剂的海南槟榔园叶片黄化症状更加明显,我们推测除草剂可能导致槟榔根系退化,从而引起叶片黄化。本试验以幼龄期槟榔与成龄期槟榔为研究对象,测定草甘膦和草铵膦使用后槟榔根系生长发育形态与相关生理指标。结果表明：（1）在幼龄期槟榔根系中,主要以直径为0～1.5mm的根为主要根系结构,数量上占到总根的88%以上,表面积占到了总根的68%以上。草甘膦和草铵膦喷施显著降低了槟榔幼苗根系鲜重、干物质积累量,白色吸收根的比例、吸收根活力。（2）在成龄期槟榔气生根中,喷施草甘膦和草铵膦均引起气生根药剂残留,且农残随施用浓度增加而变高;喷施草甘膦和草铵膦,阻碍了槟榔气生根发育。草甘膦处理第14天后气生根死亡数达到最大,而草铵膦处理第28天后达到最大。（3）草铵膦损害了气生根组织结构,使新根内皮层排列稀疏,表皮组织厚度增加,木栓化程度加深,导致根表皮细胞大量死亡,抑制了气生根伸长与增粗。上述研究结果表明草甘膦和草铵膦通过木栓化加速根系死亡调控槟榔根系生长与发育。     

液相色谱串联质谱法检测草铵膦、草甘膦及其代谢物在水和土壤中的残留

利用超高效液相色谱-串联质谱仪(UHPLC-MS/MS),结合固相萃取净化建立了在水和土壤中同时快速测定草甘膦、草铵膦及其6种代谢物的多残留分析方法。前处理采用Oasis MCX和Oasis MAX固相萃取柱提取,2%甲酸甲醇-水(体积比为1∶1)洗脱,旋干后0.1%氨水定容,UHPLC-MS/MS检测。方法的线性范围为0.02～0.5 mg/L;在水中添加水平为0.000 1 mg/L和0.001 mg/L时,草甘膦、草铵膦及其代谢物的回收率为72.8%~94.2%,RSD为2.3%~16.1%;土壤中添加水平为0.001 mg/kg和0.01 mg/kg时,草甘膦、草铵膦及其代谢物的回收率为70.6%~88.5%,RSD为3.6%~12.8%。本方法准确、灵敏、全面,适用于草甘膦、草铵膦及其代谢物在水土环境中的残留检测及监测。     

Losses of 15N-nitrogen by plant–soil system after herbicide application on black oat

Recent studies have demonstrated that the use of glyphosate or glufosinate-ammonium herbicides for some cover crop desiccation in conservationist systems could favor nitrogen (N) losses from the soil–plant system. In this context, the objective of this study was to evaluate the losses of N by the plant–soil system after the desiccation of black oat (Avena strigosa Schreb.) with the application of herbicides glyphosate, glufosinate-ammonium, or paraquat. Two greenhouse experiments were implemented using black oat plants fertilized with labeled (¹⁵N) ammonium nitrogen, and the N loss of the plant–soil system was quantified. The desiccation of black oat with glyphosate caused a reduction in root dry mass by approximately 60% in both experiments. The glyphosate and glufosinate-ammonium reduced the amount of N present in the aboveground portion; however, the paraquat herbicide did not modify it. None of the herbicides applied affected N losses in the black oat plant–soil system. However, 5–15% of the N applied as fertilizer was lost up to harvest. The results suggest that black oat can be used as a cover crop in direct sowing in order to avoid nitrogen losses in the soil–plant system.     

超高效液相-串联质谱法测定茶叶中草甘膦、草铵膦、氨甲基膦酸残留

探讨一种超高效液相-串联质谱法测定茶叶中草甘膦、草铵膦、氨甲基膦酸残留的测定方法,以期为建立茶叶中草铵膦、草甘膦及其代谢产物等农残检测方法的国家标准提供参考。茶样经超纯水、二氯甲烷提取和CAX萃取柱净化后,在硼酸盐缓冲液中与9-芴基甲基三氯甲烷(FMOC-Cl)进行衍生反应,衍生后产物在Waters HSS T3色谱柱上进行超高效液相色谱分离,质谱检测采用电喷雾正离子源、多反应离子监测模式。在0~100 ng/mL范围内,草铵膦、草甘膦和氨甲基膦酸均有良好的线性关系(R²>0.999);方法检出限为0.7 μg/kg;在不同茶类（乌龙茶、花茶、白茶）中添加浓度为2.0、4.0、10.0 μg/kg时,草甘膦的平均回收率为86.3%~100.2%,草铵膦的平均回收率为85.7%~101.5%,氨甲基膦酸的平均回收率为88.1%~98.4%;相对标准偏差(RSD)在1.1%~5.0%之间。该方法样品前处理简单,分析时间短,回收率和精密度等符合农药多残留检测技术的要求,适用于茶叶中草铵膦、草甘膦和氨甲基膦酸残留的同时检测。     

草铵膦对斑马鱼胚胎及仔鱼的毒性研究

草铵膦(glufosinate-ammonium,GLA)是一种广谱触杀型非选择性除草剂,随着在生产中应用的不断增加,其生物安全性也越来越受到人们的重视。试验以斑马鱼Danio rerio胚胎为动物模型,用不同剂量的草铵膦染毒受精后2h的斑马鱼胚胎,观察其死亡率和形态学变化,并应用原位杂交和QRT-PCR技术检测了Vasa基因表达情况,以分析草铵膦的毒性作用。结果表明:1.6μg/L的草铵膦对斑马鱼胚胎有显著致死作用、1.3μg/L的草铵膦有显著致畸作用,其中畸形表现为尾部弯曲和阻碍黑色素沉着。原位杂交结果显示:1.3μg/L的草铵膦可引起Vasa表达的部分缺失,QRT-PCR定量分析发现,草铵膦可引起斑马鱼胚胎Vasa基因表达水平下调3.8倍。表明草铵膦对斑马鱼胚胎有较强的致死毒性、致畸作用和潜在的生殖毒性。     

Competition Affects the Production of First Backcross Offspring on F1-hybrids, Brassica Napus × B. Rapa

Summary Interspecific F₁-hybrids may arise in fields with transplastomic oilseed rape where B. rapa occurs as a weed. Spilled seeds, including transplastomic F₁-hybrids with B. rapa, may germinate, which creates an opportunity for production of transplastomic BC₁ with B. rapa as father (BC_1r). Field trials were made with three different proportions of B. napus, B. rapa and F₁-hybrids and three different densities. Contrary to most studies on how plant competition affects introgression between oilseed rape and B. rapa, this study focused on offspring produced on F₁-hybrids, where the F₁-hybrids had oilseed rape as maternal parent. We estimated the BC_1r production in all combinations of proportion and density, and found that B. rapa sired from 0.6–7.8% of the offspring. At the proportion with the highest abundance of F₁-hybrids the entire paternity was assessed. There was a significant density effect on the production of BC_1r but the effect differed among proportions. Both the highest and lowest frequencies of BC_1r were obtained at high plant density. Neither the proportion nor density affected the number of BC_1r per square-meter significantly. Biomass components decreased significantly from low to intermediate density, whereas a further increase in density only affected the thousand-seed weight significantly. On the basis of the results from the present experiment we conclude that introgression of transgenes from transplastomic oilseed rape to B. rapa seems most likely at current field densities of B. napus, and when B. rapa is an abundant weed.     

草铵膦的作用机理及其应用

草铵膦(glufosinate-ammonium)是以谷氨酰胺合成酶(GS)为靶标酶的有机磷类非传导性灭生除草剂。光强、温度和湿度等环境因子对其活性有很大影响。其不但可以灭生除草，作为转基因技术研究的筛选剂，而且随着转基因抗草铵膦作物的问世，该产品的应用将进一步扩大。     

MINERALIZATION AND CORN RECOVERY OF 15NITROGEN FROM BLACK OATS RESIDUES TREATED WITH HERBICIDES

Nitrogen (N) mineralization from black oat residues (Avena strigosa), with or without previous application of herbicides, and its utilization by corn crop were investigated. The experiments were performed in a completely randomized setup, with three treatments and ten replicates. The treatments were: A) control - corn grown in soil with residues of black oats harvested without herbicide application; B) glyphosate - corn grown in soil with residues of glyphosate-desiccated black oat; and C) glufosinate - corn grown in soil with residues of black oat previously desiccated with glufosinate-ammonium. The remaining black oat residues on the soil surface were smaller in the control treatment than in glyphosate and glufosinate treatments. Black oat residues from the control treatment released 30% and 20% more carbon (C) and nitrogen (N), respectively, than from herbicide treatments. Microbial biomass carbon, total and mineral soil N arising from black oat residues were reduced by herbicide management. Black oat residues treated with glyphosate reduced corn total-N by 16%; however, dry mass yield was not affected by the treatments. Herbicide application on black oat reduced the total amount of residue-released nitrogen in the corn kernels, leaves and the whole plant. Net nitrogen mineralization from black oat residues is affected by the application of glyphosate or glufosinate-ammonium.     

Toxicity of the herbicide glufosinate-ammonium to Tetranychus urticae (Acari: Tetranychidae) under laboratory and field conditions

The toxicity of herbicides widely used in apple orchards to the two-spotted spider mite (Tetranychus urticae) was evaluated in laboratory and field studies. In a laboratory study with susceptible T. urticae, glufosinate-ammonium was highly effective against larvae, protonymphs and adults, but non-toxic to eggs. Its efficacy was much greater than that of the commonly used acaricide azocyclotin. The immatures died within 24 h after treatment, suggesting that the nymphicidal action may be attributable to a direct effect rather than an inhibitory action of chitin synthesis. Glufosinate-ammonium showed a positive temperature coefficient of toxicity against T. urticae adults at six temperatures from 10 to 32°C, being more toxic at higher temperatures. Very low levels of resistance to the herbicide were observed in the seven field-collected T. urticae populations resistant to various acaricides. Treatment with glufosinate-ammonium did not cause a repellent response from either adults or immature stages of T. urticae. Paraquat dichloride and glyphosate were ineffective against all stages of T. urticae. In a field study of a population of T. urticae, glufosinate-ammonium when sprayed to weeds caused significant decrease in T. urticae population densities in apple trees for nine weeks after treatment, as compared with the control. Thereafter, a single application of standard acaricides to apple foliage greatly reduced population densities, although there was no difference in the densities between the glufosinate-ammonium-treated and control plots. Based upon laboratory and field data, two single treatments with glufosinate-ammonium to weeds in May and a selective acaricide to apple trees in July may be used to prevent damage by T. urticae. ©1997 SCI     

Joint action of amino acid biosynthesis-inhibiting herbicides

The joint action of binary mixtures of the amino acid biosynthesis‐inhibiting herbicides glyphosate, glufosinate‐ammonium, metsulfuron‐methyl and imazapyr was assessed in pot experiments applying the Additive Dose Model (ADM). Plants of Sinapis arvensis or S. alba were sprayed with seven doses of the herbicides alone and binary fixed‐ratio mixtures of the four herbicides. In total, 73 binary mixtures were studied in six separate experiments. Mixtures of glyphosate and glufosinate‐ammonium were less phytotoxic than predicted by ADM whether commercial formulations or technical grade products were applied. In contrast, mixtures of glyphosate and metsulfuron‐methyl, glyphosate and imazapyr, glufosinate‐ammonium and metsulfuron‐methyl, glufosinate‐ammonium and imazapyr, and metsulfuron‐methyl and imazapyr either followed ADM or were synergistic. Synergism was observed most frequently for mixtures of glyphosate or glufosinate‐ammonium with metsulfuron‐methyl. Synergism was also more pronounced for commercial formulations of glyphosate and glufosinate‐ammonium than for the corresponding technical grade formulations, implying that synergism was caused by the presence of the formulation constituents of the commercial glyphosate and glufosinate‐ammonium formulations in the spray solution.