4％烟嘧磺隆减量对玉米田杂草防效及玉米产量的影响

[目的]评价4%烟嘧磺隆悬浮剂减量施用在玉米田杂草防治上的可行性。[方法]以郑单958为试验品种,研究1 500 m L/hm~24%烟嘧磺隆、750 m L/hm~24%烟嘧磺隆、750 m L/hm~24%烟嘧磺隆+增效剂A(99%甲酯化大豆油)、750 m L/hm~24%烟嘧磺隆+增效剂B(Silwet 408)4个除草剂减量施用对玉米田杂草防效及玉米产量的影响。[结果]添加增效剂能明显提高烟嘧磺隆除草剂的防效,较正常剂量或减量50%单施烟嘧磺隆处理药效提高了9.6%~27.0%,且施药后28 d药效降幅也最小,增效剂Silwet 408对玉米的安全性明显优于99%甲酯化大豆油,且防效好,玉米产量较不除草对照提高了16.6%。[结论]试验结果为玉米田杂草治理和化学除草剂减量使用提供了理论依据。     

芽前除草剂种类及浓度对桔梗种子萌发及幼苗生长的影响

为筛选适宜桔梗浓度的芽前除草剂。以蒸馏水为对照,研究二甲戊灵和异丙甲草胺2种除草剂、3种浓度对桔梗种子萌发及幼苗生长的影响。结果表明,与对照相比,异丙甲草胺显著降低种子发芽率和发芽指数,二甲戊灵显著提高种子发芽势和发芽指数,当浓度为0.32 mL/L时,桔梗种子发芽率最高。在幼苗生长阶段,二甲戊灵和异丙甲草胺均显著降低幼苗根长和株高,增加根粗和茎粗,其中0.32 mL/L二甲戊灵处理幼苗苗高、根长的降幅和根粗、茎粗的增幅度显著低于其他处理。可见,二甲戊灵浓度为0.32 mL/L对桔梗种子萌发和幼苗生长影响最小。     

几种常用除草剂对家蚕生长发育的影响

[目的]探讨4种农田常用除草剂对家蚕生长发育和产茧的影响,筛选适宜的桑园除草剂。[方法]采用毒叶添食法研究目前常用除草剂莠去津、烟嘧磺隆、硝磺草酮和草甘膦对家蚕生长发育及茧质的影响。[结果]莠去津对家蚕的毒性最大,取食毒叶第7天全部死亡;烟嘧磺隆对家蚕的毒性也较大,家蚕的死亡率高达80%,虽然有部分蚕能够泌丝结茧,但所结茧的茧质极差;硝磺草酮和草甘膦毒性较小,家蚕的存活率超过70%,大部分都能泌丝结茧;硝磺草酮和草甘膦低浓度处理基本不影响茧质,而高浓度处理降低了家蚕茧的全茧量和茧层量,对茧长和茧幅基本无影响。[结论]莠去津和烟嘧磺隆对家蚕毒性大,不适宜用于桑园除草;低浓度硝磺草酮和草甘膦对家蚕相对安全。     

两种除草剂对黑麦早期幼苗生长的影响(英文)

[目的]了解除草剂对黑麦幼苗早期生长的影响。[方法]从生理生化和细胞水平分析了2种除草剂[阿特拉津(Atrazine)和甲酰胺草磷(Amiprophos methyl,APM)]对黑麦早期幼苗生长的影响。[结果]Atrazine可明显降低黑麦幼苗叶绿素a、b和可溶性蛋白质的含量。当用0.100和1.000mg/L Atrazine处理黑麦幼苗16h时,叶绿素a、b含量分别从对照的1.26(a)、0.49(b)mg/g(FW)下降至1.15(a)、0.46(b)mg/g(FW)和0.81(a)、0.33(b)mg/g(FW)。可溶性蛋白质含量则随着Atrazine处理浓度的增加而减少。Atrazine对黑麦分生组织细胞有丝分裂和染色体结构无显著影响。APM处理后,黑麦幼苗叶绿素a、b和可溶性蛋白质含量无显著变化,但分生组织细胞有丝分裂和染色体结构变异如桥、多极分裂、滞后染色体和不均等分裂中期细胞数量显著增加。[结论]黑麦中Atrazine使用的临界剂量为0.100~1.000mg/L,而APM为4.000mg/L。     

3种除草剂对黑土脲酶活性的影响

[目的]为合理用药用肥提供科学依据。[方法]采用实验室模拟恒温培养的方法,研究了莠去津、乙草胺、烟嘧磺隆对高、中、低3种肥力黑土脲酶活性的影响。[结果]在试验浓度范围内,3种除草剂均对土壤脲酶有影响,而且浓度越大,影响越明显。莠去津和烟嘧磺隆对土壤脲酶有一定的抑制作用,乙草胺对土壤脲酶有一定的激活作用。[结论]对3种土壤的影响程度均是低产田土〉中产田土〉高产田土。     

Nitric oxide reduces oxidative stress generated by lactofen in soybean plants

Nitric oxide (NO) is a molecule able to directly scavenge ROS and end chain reactions, which can be generated by some herbicides. This study aimed to evaluate whether the pretreatment of soybean plants with sodium nitroprusside (SNP) solution, a NO-donor substance, provides protection against oxidative stress generated by lactofen. Soybean plants were pretreated with SNP before lactofen application. The levels of lipoperoxides and photosynthetic pigments were quantified, and the activity of the antioxidant enzymes glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) was assessed. Although lipid peroxidation was not completely prevented, NO was able to scavenge ROS generated by the lactofen action, avoiding the photosynthetic pigment breakdown. Consequently, ROS scavenging by NO leads to a decrease in the available substrate for the antioxidant enzymes SOD, CAT, and POD, which are essential to protect plants under oxidative stress situations such as absence of GST induction by H₂O₂.     

几种不同茎叶处理除草剂对谷子的安全性研究

采用随机完全区组试验设计,在大田条件下研究了百草敌、2甲4氯、2,4-D丁酯对谷子形态指标及生理代谢的影响,探讨了除草剂对谷子生长的安全性。结果表明,3种药剂中,百草敌对谷子形态指标和生理指标的抑制率均最小,对谷子产量的影响未达显著水平,对谷子较安全;2,4-D丁酯对谷子的安全性最差,对谷子各项形态指标和生理指标的抑制率均最大,对谷子产量有显著的影响;2甲4氯对谷子的安全性居中。由此可见,百草敌可作为谷子田较理想的除草剂。     

Evaluation of some weed control treatments for long season weed control in maize (Zea mays L.) under zero and minimum tillage at Samaru, in Nigeria

The effect of weed control treatments for long season control of weeds in maize under zero and minimum tillage was evaluated at Samara in northern Nigeria. Among the weed control treatments evaluated, soil ridging plus application of either 2,4-D or atrazine at 1.5 kg a.i/ha performed well as they effectively controlled weeds and resulted in better growth and a grain yield that was comparable to the hand weed control. Maize production under minimum tillage was better than under zero tillage.     

Effect of some Herbicides on Oil Seed Rape (Brassica Napus L.) and Associated Weeds

Two field experiments were conducted during 1984/1985 and 1985/1986 seasons to study the effect of Alachlor, Metolachlor, Pendimethalin, Diphenamid, CGA 10832 and Oxadiazon as pre-emergence herbicides and EPTC as presowing herbicide at two doses as well as hand-hoeing treatment on weed spread and rapeseed yield under Egyptian conditions. All the tested herbicides except "Oxadiazon" gave satisfactorily good annual grass weed control up to harvest time. While, Oxadiazon and Diphenamid at both doses controlled adequately the growth of annual broad-leaved weeds. The highest rapeseed yield was achieved under the application of Metolachlor at 2.4 and 3.6, Pendimethalin at 1.8, Diphenamid at 1.8, CGA 10832 at 2.4 and Oxadiazon at 1.2 kg a.i./ha. While, Pendimethalin at 2.4, Diphenamid at 2.4, CGA 10832 at 3.6, Oxadiazon at 1.8 and EPTC at 5.5 kg a.i./ha exhibited an obvious phytotoxic effect on rapeseed plants.     

Soil microbial community response to surfactants and herbicides in two soils

The environmental impacts of herbicides on desirable plants and the soil biota are of public concern. The surfactants that are often used with herbicides are also under scrutiny as potentially harmful to soil biological systems. To address these concerns, we used two soils, a silt loam and a silty, clay loam from south central Missouri, to investigate the impacts of herbicides and surfactants on soil microbial communities using phospholipid fatty acid (PLFA) analysis. The surfactants used in this study were alkylphenol ethoxylate plus alcohol ethoxylate (Activator 90), polyethoxylate (Agri-Dex), and a blend of ammonium sulfate, drift reduction/deposition polymers and anti-foam agent (Thrust). The herbicides were glyphosate, atrazine and bentazon. Surfactants and herbicides were applied to soils at label rate, either alone or combined, to 4000 g soil per pot. The two soils differed in history, texture, some chemical characteristics and several microbial community characteristics. A few of the chemicals altered some of the components of the microbial community after only one application of the chemical at field-rate. The Cole County, MO silt loam showed larger changes in the microbial community with application of treatments. For the Boone County, MO silty clay loam, Activator 90, Agri-Dex and bentazon treatments increased microbial biomass determined by PLFA; Thrust decreased PLFA markers, bacteria to fungi ratio; and Agri-Dex at both rates decreased monounsaturated fatty acids. Changes in the microbial community due to herbicides or surfactants were minimal in this study of a single application of these chemicals, but could be indicators of potential long-term effects. Long-term studies are needed to determine the changes in the microbial community after several years of annual applications of herbicides and surfactants on a wide array of soil types and management practices.