单季晚稻机插田化学除草技术

[目的]随着小苗机插稻田面积的扩大,机插田草害发生也日益严重,为有效控制机插田杂草的危害,2008—2009年在浙江省桐庐县单季晚稻机插田进行不同施药时期和施药剂量对主要杂草防效试验。[结果]5%丁草胺GR 750 g a.i./hm2+10%苄嘧磺隆WP 30 g a.i./hm2和20%乙.苄WP 90 g a.i./hm2在插后3 d施药,插后50 d对总草鲜质量防效极显著高于插后7 d的防效。53%苄嘧.苯噻酰WP 318、477、636 g a.i./hm2于插后5 d施药,药后30、50 d,对异型莎草、阔叶草、总杂草的防效有差异;而50%苄.丁.异丙隆WP 450、600 g a.i./hm2的防效差异均不显著;药后50 d对总草株防效均达93%以上、鲜质量防效99%以上,且增产8.2%~14.4%。上述处理除20%乙.苄WP 90 g a.i./hm2在药后15 d内对机插稻有一定影响外,其余均较安全。[结论]在小苗机插后3~5 d,使用5%丁草胺GR 750 g a.i./hm2+10%苄嘧磺隆WP 30 g a.i./hm2或53%苄嘧.苯噻酰WP 318~636 g a.i./hm2,或...     

丹东港进口大豆携带杂草种类与检测

丹东港是中国海岸线最北端的不冻良港,近年来从该口岸进境的大豆数量逐年增加,从2009年至今,丹东港约有280万吨大豆进境,主要来自美国和巴西。从进口大豆检出杂草情况看,杂草种类繁多,共17科、74种,其中检疫性杂草有5科、11种。本文对丹东港进口大豆携带的杂草进行了分类与风险分析,并提出相应的一些建议,从而降低有害生物的传入几率。     

直播稻田化学除草试验

直播稻田用不同药剂在播种后各一次化除或播种后两次化除都具有很好的除草效果。播后前期是化学除草的关键时期播后前期每６６７米＾２用１０％苄嘧黄隆１５克＋６０％丁划胺６０毫升，１０％苄嘧黄隆１５克＋５０％杀草丹１５０毫升，１７．２％新幼禾葆２４０克或１５．８％幼禾葆２００克防铲均较好。     

8%精喹·乳氟禾乳油防除花生田杂草试验

为明确8%精喹·乳氟禾乳油防除花生田杂草的效果和对花生的安全性,采用田间小区试验的方法,观察其对花生田杂草的防效和对花生产量的影响。结果表明,8%精喹.乳氟禾乳油有效成分用量100.0～240.0 g/hm2对花生田马唐、牛筋草、反枝苋、马齿苋等杂草均有好的防治效果,药后20 d,总体株防效为96.45%～99.68%,鲜重防效97.93%～99.83%。对作物花生安全性较好,药后部分叶片出现药害斑,不扩展,可恢复,对花生苗期生长无影响,增产率33.42%～47.33%。     

Comparison of the wound-activated transformation of caulerpenyne by invasive and noninvasive Caulerpa species of the Mediterranean

The invasive green alga, Caulerpa taxifolia, that has spread rapidly after its introduction into the Mediterranean and the North American Pacific, reacts to wounding by transforming its major metabolite caulerpenyne (1). This wound-activated reaction involves the transformation of the bis-enol acetate moiety of 1, releasing reactive 1,4-dialdehydes. The ability to perform this transformation is found also in both the noninvasive Mediterranean C. prolifera and the invasive C. racemosa. Trapping experiments, as well as transformation of the model substrate geranyl acetate, suggest that all three investigated Caulerpa spp. rely on esterases that act upon wounding of the algae by subsequently removing the three acetate residues of caulerpenyne. The resulting reactive 1,4-dialdehyde oxytoxin 2 (9) can be identified by liquid chromatography–mass spectrometry and is unstable in the wounded tissue. Caulerpenyne transformation occurs rapidly, and severe tissue damage caused degradation of more than 50% of the stored caulerpenyne within 1 min in all three algae. Prevention of the enzymatic reaction before extraction, by shock freezing the tissue with liquid nitrogen, was used for the determination of the caulerpenyne content in intact algae. It gives about twofold higher values compared to an established methanol extraction protocol. The speed and mechanism of the wound-activated transformation, as well as the caulerpenyne content in intact tissue of invasive and noninvasive Caulerpa spp., are comparable. Thus, this enzymatic , transformation, despite being fast and efficient, is likely not the key for the success of the investigated invasive species.     

Why Phenolic Acids Are Unlikely Primary Allelochemicals in Rice

Allelopathy in rice (Oryza sativa, L.) effective against weeds has been found in about 3.5% of tested rice germplasm in both laboratory and field experimentation. However, the allelochemicals responsible for growth inhibition of rice-associated weeds have not yet been identified. In the literature, phenolic acids are often mentioned as putative allelochemicals. If phenolic acids commonly reach growth inhibitory concentrations in rice ecosystems, it must be expected that the degree of tolerance to phenolic acids will vary among traditional rice cultivars or plant species adapted to rice environments having inherently different phenolic acid concentrations. Phenolic acids concentrations are normally greater in submerged than in aerobic soils. A dose–response study, however, showed that seedlings of rice cultivars adapted to submerged anaerobic soils did not have higher level of tolerance against p-hydroxybenzoic acid than did seedlings of varieties adapted to aerobic upland soils. Moreover, traditional rice cultivars had no greater tolerance than did improved cultivars that were recently bred for traits other than tolerance of phenolic acids. Similarly, there were no differences in tolerance of p-hydroxybenzoic acid between two Echinochloa weed species adapted to either anaerobic or aerobic growth conditions. Thus, neither the rice cultivars nor weed species had evolved different tolerance levels against the phenolic acid. However, all rice cultivars had significantly greater tolerance of p-hydroxybenzoic acid than did either weed species. In a second experiment, the rates at which rice plants released phenolic acids into solution cultures were measured for at least one month, the time period of greatest allelopathic activity following planting under field conditions. The maximum release rate of phenolic acids during the first month of growth was approximately 10 g/plant/day. At a conventional plant density, the release rate of phenolic acids would be approximately 1 mg/m²day. This order of release rate cannot provide concentrations remotely close to phytotoxic levels determined for these rice cultivars and weed species. The results presented in this paper do not preclude the possibility that phenolic acids might be one component in a mixture of chemicals that, when present simultaneously, are allelopathic.     

氟嘧磺隆的合成研究与田间除草效果

以2-氨基-4，6-二羟基嘧啶为起始原料，选用高效催化剂A，经二氟甲基化后得到2-氨基-4。6-双(二氟甲氧基)嘧啶(DMAP)；DMAP在溶剂B中与邻甲氧甲酰苯磺酰异氰酸酯加成合成氟嘧磺隆，合成总收率21％。产品含量达97％。田间试验结果表明：10％氟嘧磺隆可涅性粉剂7．5、15和30g a．i．／hm^2对玉米田阔叶杂草的防效分别为77％、89％和95％，对禾本科杂草的防效分别为40％、54％和63％；对玉米安全；各处理区玉米产量和玉米穗轴重均明显高于对照区产量和穗轴重。     

磺草酮对玉米的安全性及除草效果评价

田间测定了磺草酮对玉米的安全性及防除杂草试验效果，结果表明磺草酮有效成分562．5～1200g／hm^2防除玉米田单子叶杂草马唐、牛筋草、狗尾草效果较好，防效为86．5％～98．0％；对双子叶杂草中的反枝苋防效较好，防效为99．3％～l00％；对铁苋莱和马齿苋防效较差，防效为35．0％～62．9％。对玉米有触杀性药害，至药后15天药害症状消失，不影响玉米的产量，且有较好的增产作用，增产l0．0％左右。     

Application of Hyphenated Chromatography–Mass Spectrometry Techniques to Plant Allelopathy Research

Plant allelopathy offers hope as an additional means of weed control in modern agriculture. Its mechanisms and molecular basis are not yet well understood. Research on the chemical basis for allelopathy has often been hindered by the complexity of plant and soil matrices, making it difficult to track active compounds. Recent improvements in the cost and capabilities of bench-top chromatography–mass spectrometry instruments make these tools more powerful and more widely available to assist with molecular studies conducted in today's expanding field. Such instrumental techniques are herein recommended as economically efficient means of advancing the rigor of allelopathy research and assisting the development of a better understanding of the chemical basis for the allelopathy phenomenon.     

50%仲灵·乙草胺乳油对大豆田杂草药效及安全性

为验证50%仲灵.乙草胺乳油对大豆田杂草的药效、杀草谱及对大豆生长的安全性,采用播后苗前土壤喷雾处理、定期调查的方法进行田间药效试验。结果表明,药剂50%仲灵.乙草胺乳油的杀草谱较广,对一年生禾本科杂草及大部分阔叶杂草有良好的防效。施药后20 d调查,对各种杂草株防效为77.0%～96.3%;施药后40 d调查,对各种杂草株防效为79.5%～97.0%。对大豆产量未见不良影响。50%仲灵.乙草胺乳油适宜有效成分用量为1500～2250 g/hm2,对水750L/hm2,播后苗前土壤喷雾。