回归设计应用于大豆化学除草配方最佳剂量的筛选初探

本文对Ｄ－饱合设计法应用于大豆田化学除草剂混配最佳剂量的筛选进行了初步探索，并建立了拉索、丁草胺、广灭灵三种药剂用量与除草效果、杂草鲜重的数学模型，经Ｘ２与相关检验，模型的拟合度极好，具有推广价值。应用微机进行仿真模拟，获得了此三种除草剂混配应用于大豆田除草的最佳剂量为：（拉索８７．７－１２８．７ｍＬ＋丁草胺１０８．７～１３８．８ｍＬ＋广灭灵５０．１～６３．１ｍＬ）／６６７ｍ２。     

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.     

Studies of clomazone mode of action

Intact spinach chloroplasts were used to determine if clomazone, 5-OH clomazone, and/or 5-keto clomazone inhibited the chloroplastic isoprenoid pathway. When isopentenyl pyrophosphate was used as a precursor, neither clomazone nor the clomazone metabolites (5-OH clomazone and 5-keto clomazone) inhibited the formation of products separated by HPLC in the organic phase. However, when pyruvate, a substrate for the first committed step of the pathway, was used as a precursor, both 5-keto clomazone and fosmidomycin reduced the formation of a non-polar product and increased the formation of a polar product in the organic phase. Only 5-keto clomazone, not 5-OH clomazone or clomazone, inhibited the formation of an additional product other than fosmidomycin in the aqueous phase from pyruvate incorporation. In an in vitro assay, 5-keto clomazone inhibited DXP synthase, the enzyme catalyzing the first committed step of the chloroplastic isoprenoid pathway. Therefore, our studies show that neither clomazone nor 5-OH clomazone inhibits the chloroplastic isoprenoid pathway, only 5-keto clomazone does.     

3种药剂对山楂异噁草松药害的缓解效果比较

[目的]探究异噁草松药害的缓解方法.[方法]以遭受异噁草松药害程度相近的山楂为研究对象,研究了绿叶灵、解害灵、自配试剂3种试剂对其白化叶片的复绿效果.[结果]自配试剂的复绿效果显著优于绿叶灵与解害灵,缓解药害效果显著.[结论]试验自配试剂可望用于缓解异噁草松药害.     

长残留除草剂广灭灵的生物测定方法

试验以小麦、玉米等作物为指示植物,分别以株高和叶绿素的含量为生物测定指标,在不同的培养条件下,对广灭灵生物测定方法进行筛选。结果表明,利用土培生测法培养的小麦株高抑制率与药剂的浓度在不同的范围内有显著的相关性;通过连续测定玉米叶片中叶绿素的含量,发现培养至第6天的玉米叶片叶绿素含量抑制率和药剂浓度相关性最好,并在低浓度范围内表现出药剂对叶绿素含量提高有促进作用。以玉米叶绿素含量作为生测指标不仅指示的浓度范围广,还具有良好的重现性,是广灭灵理想的生物测定指标之一。     

水稻土中广灭灵残留动态及降解影响因子的研究

对水稻土中广灭灵残留消解动态及降解影响因子研究结果表明 ,广灭灵在 4种水稻土中降解符合 1级动力学方程C =C0 e-kt,其降解半衰期为 5 7～ 2 2 0d。广灭灵降解以微生物降解为主 ,土壤灭菌处理大大降低广灭灵降解速率 ,土壤理化性质、温度、湿度、pH值是影响广灭灵降解的重要因素。广灭灵降解速率与不同类型水稻土有机质含量呈显著负相关关系 ,相关系数为 - 0 8336。随温度上升而广灭灵降解有加速趋势 ,但常温 2 5℃时广灭灵降解速率高于 35℃处理 ,增加土壤湿度及施用石灰增加土壤 pH值均加快广灭灵降解速率     

生物炭对土壤残留异噁草松的生物有害性影响研究

通过混土施药模拟长残效除草剂的土壤残留环境,揭示生物炭对异噁草松土壤残留的生物有害性的影响。结果表明,土壤中异噁草松残留量低于0.12mg/kg,对幼苗生长有促进作用,高于该阈值,逐渐表现为抑制作用;异噁草松残留达到0.96mg/kg时,幼苗生长基本处于停滞状态,施入生物炭能够有效降低其生物有害性;异噁草松残留超过0.72mg/kg时,不加生物炭处理,造成穗秃尖率大、结实率低、子粒成熟度差、含水率高;添加生物炭对玉米生长有一定的促进作用,产量平均增加10.25%;通过模拟试验预测:前茬大豆田异噁草松施用量低于2250mL/hm²,对下茬玉米生长可能会有一定的促进作用;连续几年喷药量高于4500mL/hm²,可产生一定程度的药害。生物炭对土壤中一定阈值范围内的异噁草松残留具有降低生物有害性的作用。     

50%乙·异噁松EC防除油菜田杂草药效试验

防除油菜田杂草药效试验结果表明:施用50%乙.异噁松EC有效成分525~1125 g/hm2后第30、60、90 d对看麦娘、网草和牛繁缕的综合密度防效分别为92.32%~100%、91.07%~99.68%、92.07%~99.83%,第90 d的综合鲜重防效高达93%以上;施用该药剂能显著提高油菜田间的透光率,降低杂草对田间养分和水分的吸收,对油菜的增产率为29.01%~29.48%。     

Effect of herbicide and cover crop on weed control in no-tillage jack-o-lantern pumpkin (Cucurbita pepo L.) production

Field experiments were conducted to evaluate cover crop (none, winter wheat, or winter rye) and pre-emergence (PRE) applications of clomazone plus ethalfluralin alone or with halosulfuron [PRE or post-emergence (POST)] for smooth crabgrass [Digitaria ischaemum (Schreb. ex Schweig) Schreb. ex Muhl.] and redroot pigweed (Amaranthus retroflexus L.) control in no-tillage ‘Aspen’ jack-o-lantern pumpkin (Cucurbita pepo L.). At pumpkin harvest, cover crops had reduced smooth crabgrass density, but not redroot pigweed. Although PRE or POST applications of halosulfuron alone were more effective at reducing redroot pigweed density than clomazone plus ethalfluralin PRE, the combination of halosulfuron plus clomazone and ethalfluralin PRE reduced redroot pigweed density to the greatest extent. Pumpkin yields were not affected by cover crop, although average pumpkin sizes were greater with the inclusion of cover crop residues. Pumpkin fruit sizes and yields were the greatest with clomazone and ethalfluralin PRE in combination with halosulfuron applied PRE or POST. Overall, cover crop had relatively little influence on pumpkin yields compared with herbicide treatments. The addition of halosulfuron to clomazone and ethalfluralin provided greater broadleaf weed control resulting in greater jack-o-lantern pumpkin yields.     

异恶草酮脲醛树脂微胶囊剂的研制

[目的]研究除草剂异恶草酮微胶囊的反应工艺。[方法]用原位聚合法制备以脲醛树脂为壁材的除草剂异恶草酮微胶囊剂,讨论乳化剂、搅拌速度、尿素-甲醛量比和芯皮比等对微胶囊的粒径及分布、结构、包埋率和缓释性的影响。[结果]选用OP-10为乳化剂,均质速度2000r/min,尿素-甲醛量比为1：2,芯皮比为1：1.5,控制一定的终点pH值和酸化时间,可制得结构紧密、包埋率为26.7%、粒径分布均匀且平均粒径在0.6μm左右的流动性球形固体微胶囊。[结论]异恶草酮脲醛树脂微胶囊剂是一种环境友好型制剂。