我国小麦田禾本科杂草对精噁唑禾草灵的抗药性研究进展

小麦是我国主要的粮食作物, 麦田草害的发生与危害严重影响小麦的产量与品质。我国小麦田的禾本科杂草主要包括日本看麦娘、看麦娘、菵草和多花黑麦草等, 田间杂草防除主要依靠化学除草剂。精噁唑禾草灵自20世纪80年代进入我国市场以来, 长期用于小麦田禾本科杂草防除, 已经报道麦田多种禾本科杂草对精噁唑禾草灵产生了高水平抗药性。为更加科学合理地控制小麦田杂草的发生与危害, 一些学者就麦田禾本科杂草对精噁唑禾草灵的抗药性水平监测和抗性机理进行了系统研究。本文系统总结了我国小麦田抗精噁唑禾草灵杂草的发生种群、抗性水平、靶标酶抗性机理与非靶标抗性机理, 还梳理了抗性杂草的交互抗性与多抗性发生情况, 分析了我国在抗性杂草治理方面的经验以及面临的问题, 为农田杂草防除提供指导。     

小麦田大穗看麦娘对精噁唑禾草灵的抗性

为明确小麦田大穗看麦娘对精噁唑禾草灵的抗性水平及产生抗性的机理,采用整株法测定了河南省小麦田大穗看麦娘种群对精噁唑禾草灵的抗性水平,以及细胞色素P450s抑制剂胡椒基丁醚(PBO)对精噁唑禾草灵的增效作用,并通过基因测序技术研究了其靶标ACCase基因的突变位点。结果显示:与敏感种群HN-06相比,抗性种群HN-05对精噁唑禾草灵的抗性倍数为52.2,其ACCase基因存在Ile-2041-Asn和Gly-2096-Ala位点突变;喷施PBO后,精噁唑禾草灵对大穗看麦娘的GR50值(有效成分)为5.4 g/hm^2,表现出明显的增效作用,与未喷施PBO处理的差异倍数为161.3。研究表明,抗性种群HN-05对精噁唑禾草灵已产生高水平抗性,该抗性的产生可能是由于其靶标基因突变和P450s介导的代谢增强同时导致的,即表现出了靶标抗性和非靶标抗性共存的现象。     

环嗪酮的环境行为研究进展

综述了环嗪酮的环境行为研究，包括其残留分析方法，水解，微生物降解，土壤降解，安全性评价，对非靶标生物的毒性测定，降解产物的研究等方面。     

精恶唑禾草灵防除小麦田杂草看麦娘田间药效试验

精恶唑禾草灵属选择性、内吸传导型苗后茎叶处理剂,可用于阔叶作物如大豆、棉花、花生、油菜、蔬菜等防治一年生禾本科杂草,精恶唑禾草灵加入安全剂解草唑后,可增强小麦对精恶唑禾草灵的耐药性,用于小麦田防除一年及多年生禾本科杂草。为明确精恶唑禾草灵对麦田常见恶性杂草看麦娘的具体防效,笔者于2011年初,进行了精恶唑禾草灵防除冬小...     

小麦田精噁唑禾草灵抗性杂草的田间监测与防控

田间监测试验表明,69g/L精噁唑禾草灵EW在小麦田疑似抗性杂草种群试验区对看麦娘、野燕麦、菵草等一年生禾本科杂草防效较差,综合株防效只有58.21%,综合鲜重防效也只有67.67%;69g/L精噁唑禾草灵EW在小麦田敏感杂草种群试验区对看麦娘、野燕麦、菵草等一年生禾本科杂草防效较好,综合株防效87.61%,综合鲜重防效88.48%。表明多年使用精噁唑禾草灵的小麦田看麦娘、野燕麦、菵草等种群均已对精噁唑禾草灵产生了抗药性。     

手性除草剂研究进展

以几大类已经商品化或具有较好市场前景的手性除草剂为对象,综述了各除草剂的除草活性、对非靶标生物的毒性及其在环境迁移中的对映异构体选择性现象及机理的研究成果。由于对映异构体间的生物学性质迥异,因此,手性除草剂对映异构体的活性、作用机理、代谢转化及其在生物体内的转移等都具有手性选择性差异。同时,手性除草剂对植物的选择性作用还会因作用对象及环境因素的改变而改变,其在环境中的选择性降解情况也十分复杂,不仅与该除草剂自身的理化性质有关,还与其所处的环境因素有关,诸如土壤类型、植物种类、微生物群落结构、温度、pH值等均会改变手性除草剂对映异构体的环境归趋。     

扑草净在养殖水体中的生态毒理效应及其微生物降解的研究进展

扑草净是一种均三氮苯类除草剂,近年来被广泛应用于水产养殖中,在清除水体青苔和杂草方面卓有成效。但因其具有较难降解的特性而对养殖水环境存在着污染隐患。本文阐述了扑草净在养殖水体中的生态毒理效应及其微生物降解的研究进展,以期引起相关研究者的关注和重视。扑草净对养殖水体中的水生生物具有一定的急性毒性,其对水草和藻类属于高毒物质,对鱼、虾类的毒性介于中毒和高毒之间,并可通过藻类间接影响鱼虾的生长代谢。扑草净在环境中的半衰期长达数月,但在一定条件下可被微生物降解。降解微生物包括细菌、真菌等20多种。微生物对扑草净的降解主要是通过酶促反应完成的,受物质本身结构、环境温度、pH等多种因素的影响,多种微生物共存时的降解效果较好。目前利用微生物降解扑草净的研究多数还停留在试验阶段,实际生产中尚无规模化的应用,对其在降解过程中可能产生的中间产物及毒性效应研究不多。因此如何有效地筛选高活性的降解菌株,降低扑草净在养殖环境中的停留,减少对水生生物的毒性将是未来研究的目标和方向。     

甲草胺对非靶标生物的毒理学研究进展

甲草胺是一种选择性芽前除草剂,在20世纪末期被广泛应用于防治大豆、花生、水稻田等一年生禾本科及阔叶杂草。目前,甲草胺由于其致畸性及内分泌干扰活性已被多国禁用。文章综述了甲草胺进入环境后对非靶标生物的毒理学研究进展,主要包括急性毒性、慢性毒性和氧化应激效应等,旨在为甲草胺生态环境风险评估提供数据资料。     

助剂激健对甲基二磺隆防除抗精■唑禾草灵菵草的增效作用

旨在明确助剂激健(主要成分为非离子表面活性剂、油酸甲酯、玉米胚芽油、油茶籽油等)对甲基二磺隆防除抗精■唑禾草灵菵草是否具有增效作用,并探究其最佳增效剂量及机制。采用室内整株生物测定法筛选激健对甲基二磺隆防除抗精■唑禾草灵菵草的最佳增效剂量,并通过测定激健对药液表面张力、接触角、扩展直径、最大持留量等物理指标的影响,以及对抗精■唑禾草灵菵草乙酰乳酸合酶(ALS)活性的影响,来阐明其增效作用机制。结果表明,助剂激健和甲基二磺隆的最佳增效组合为甲基二磺隆12 g a.i./hm~2+激健0.05%(体积分数);激健能显著降低药液的表面张力及接触角,显著增加扩展直径及最大持留量;激健对抗精■唑禾草灵菵草ALS活性无显著影响。由结果可以看出,助剂激健对甲基二磺隆防除抗精■唑禾草灵菵草具有增效作用,主要是通过改变药液理化性质而发挥增效作用,而不是在生理生化水平上对甲基二磺隆的靶标酶活性产生影响。     

八种除草剂对多异瓢虫不同虫态的安全性评价

在新疆棉区，早春季节田埂杂草上滋养的天敌昆虫，是棉田内天敌的主要来源，也是棉田外天敌保育的重点。生产上，常喷施除草剂来防除田埂上的恶性杂草，从而除草剂可能会对非靶标天敌昆虫产生直接的不利影响。本文评价了新疆农田中常用的8种除草剂对多异瓢虫不同虫态存活的影响，发现8种除草剂喷施对多异瓢虫卵孵化率、蛹羽化率、成虫存活率均没有显著影响，精喹禾灵、苯磺隆、精噁唑禾草灵处理后3龄幼虫的存活率显著低于对照，而高效氟吡甲禾灵、精吡氟禾草灵、烯草酮、氯氟吡氧乙酸、乙氧氟草醚处理组的幼虫存活率与对照没有显著差异。利用高效氟吡甲禾灵、乙氧氟草醚药液处理多异瓢虫卵后，对卵、幼虫、蛹历期以及各虫态存活率、蛹重等均无明显影响，仅高效氟吡甲禾灵处理组幼虫化蛹率显著降低。利用高效氟吡甲禾灵、乙氧氟草醚处理3龄幼虫后，对其生长发育没有显著影响。本研究证实，新疆农田常用的8种除草剂对多异瓢虫比较安全，没有明显的毒杀作用与负面效应。     

不同覆盖材料下土壤水温效应对玉米前期生长的影响

本研究旨在比较盆栽与大田试验条件下不同覆盖材料的土壤调温保湿效果,为选择农业环保型覆盖材料提供理论依据。2014和2015年分别设置盆栽试验和大田试验,覆盖塑料地膜(DM)、液体地膜(YM)、麻地膜(MM)及秸秆(JM)等4种材料,以不覆盖处理为对照(CK),分析了不同覆盖材料对土壤水温状况及玉米前期生长的影响。结果表明:麻地膜覆盖对玉米生育前期0~20 cm土层土壤的保水保墒效果最好,秸秆覆盖处理次之,麻地膜覆盖和秸秆覆盖处理玉米出苗至大喇叭口期平均土壤贮水量分别较对照显著提高29.0%和26.6%。覆盖不同材料的调温作用:2014年盆栽试验玉米拔节期各处理升温效果表现为MMDMJMYMCK,大喇叭口期其降温效果表现为MMJMCKDMYM;2015年大田试验玉米拔节期各处理升温效果表现为CKDMMMYMJM,大喇叭口期其降温效果表现为CKDMMMJMYM。麻地膜覆盖处理促进了玉米前期的生长,比不覆盖处理提前10~11 d进入大喇叭口期,玉米株高、茎粗、叶面积及生物量分别较对照显著提高48.3%、27.5%、158.2%和63.5%。     

Comparing ecological risks of pesticides: the utility of a Risk Quotient ranking approach across refinements of exposure

Environmental risk assessment of pesticides and other chemicals often uses the Risk Quotient (RQ) method to characterize risk quantitatively. An RQ is calculated by dividing an environmental exposure value by a toxicity end-point value. Tier 1 RQs, which are characterized by highly conservative toxicity and exposure assumptions, are used primarily for screening out negligible risks in regulatory decision making. It has been argued that the tier 1 RQ approach is valuable for making direct comparisons of quantitative risk between pesticides. However, an outstanding question is whether relative risks among pesticides would change if refinements of exposure are incorporated into the RQ calculations. This study tested that hypothesis. Aquatic ecological risk assessments were conducted for 12 herbicide and 12 insecticide active ingredients used on agricultural crops in the USA. The pesticides were chosen because surface-water monitoring data for them were available as part of the United States Geological Survey's National Water-Quality Assessment Program (NAWQA). Ecological receptors and effects evaluated were aquatic non-vascular plants (acute risk), aquatic vertebrates (acute risk) and aquatic invertebrates (acute risk) for the herbicides and aquatic vertebrates (acute and chronic risk) and aquatic invertebrates (acute and chronic risk) for the insecticides. The data indicate that there were significant statistical correlations between numerical rankings of tier 1 RQs and RQs using refined environmental exposures. The results support the hypothesis that numerical ranking of RQs for the purpose of comparing potential ecological risks is a valid approach because the rankings are significantly correlated regardless of the degree of exposure refinement.     

Rice paddy field herbicides and their effects on the environment and ecosystems

Paddy herbicides contribute to the reduction of weeding labor, however, there are concerns about their effects on the environment and ecosystems. The environmental burden of applied herbicides is heaviest in water systems such as irrigation channels and rivers. Herbicides are generally detected in rivers in concentrations in levels of ng/L for only 2 to 3 months after use. It is to be regretted that herbicides have been implicated in accidents involving fish, the impeded propagation of algae and other non‐target organisms. Therefore, it is necessary to assess the ecological risk, and the Environment Agency in Japan compiled an interim report on how pesticides' ecological effects should be assessed. Pesticides are separately examined for their toxicity (hazard assessment) and exposure (exposure analysis). However, to the environment and ecosystems there are many problems in assessing the ecological risk of pesticides, such as selection of geographic locations, methodology of assessing the impacts on ecosystems and monitoring the effect of pesticides. New herbicides are expected to have high selectivity and low toxicity. Decreasing herbicide toxicity requires high selectivity to distinguish target weeds from crops and non‐target organisms. New groups of compounds will be developed based on a biorational approach. Moreover, it is necessary to develop an environmentally low‐impact application method such as the use of granular types and sustained‐release formulation among others. It is important that integrated methods be used to control paddy weeds by combining ecological/agronomical, mechanical and biological control methods, instead of relying solely on chemical herbicides.     

Grazing exclusion-induced shifts,the relative importance of environmental filtering,biotic interactions and dispersal limitation in shaping desert steppe communities,northern China

Grazing exclusion is one of the most efficient approaches to restore degraded grassland but may negatively affects the recovery of species diversity. Changes in plant species diversity should be a consequence of the ecological assembly process. Local community assembly is influenced by environmental filtering, biotic interactions, and dispersal. However, how these factors potentially contribute to changes to species diversity is poorly understood, especially in harsh environments. In this study, two management sites within a Stipa breviflora desert steppe community(typical natural steppe) were selected in northern China. In one of the two management sites, grazing has been excluded since 2010 and in the other with open grazing by sheep. In August 2016, three plots were established and 100 sampling units were created within each plot in a 5 m×5 m area at the two management sites. To assess the effects of grazing exclusion on S. breviflora steppe, we analyzed the vegetation biomass, species diversity,soil organic carbon, and soil particle size distribution using paired T-tests. In addition, variation partitioning was applied to determine the relative importance of environmental filtering and dispersal limitation. Null mode analysis was used to quantify the influence of biotic interactions in conjunction with Eco Sim niche overlap and co-occurrence values. Our results demonstrated that(1) species diversity significantly decreased and the main improvements in soil quality occurred in the topsoil 0–10 cm after the grazing exclusion;(2) environmental filtering was important for community assembly between grazed and fenced grassland and this appears particularly true for soil particle size distribution, which may be well correlated with soil hydrological processes; and(3) however, competitive exclusion may play a significant role within the exclusion. The multiple pathways of assembly may collectively determine negative effects on the restoration of species diversity. Therefore, designers should be aware of the risk of reducing grazing exclusion-induced species diversity and account for manipulating processes. This in turn will reduce dominant species and promote environmental heterogeneity to maximize species diversity in semi-arid regions.     

农药对蚯蚓的生长和繁殖毒性及其在生态风险评价中的应用

蚯蚓占了陆生无脊椎生物生物量的绝大部分,是农田生态系统土壤物质循环中的重要一环,且蚯蚓对某些污染物比许多其它土壤动物更为敏感,是陆生生态系统中土壤农用化学品污染的理想指示生物。死亡率是最常用于评估化学品对蚯蚓毒性的参数,但大多数情况下蚯蚓死亡率变化对农用化学品暴露并不敏感,因此急性毒性测试结果并不能为评估化学品对蚯蚓种群危害提供最敏感的风险预测。因此,研究更多可应用于土壤污染评价的蚯蚓生物标志物十分有意义,可对保护整个土壤动物区系的安全阈值设定提供参考。本文从蚯蚓常用毒理学研究方法入手,重点综述了农药对蚯蚓的生长和繁殖毒性效应以及相关毒理学测试指标在农药土壤生物风险评价中的应用,并讨论了影响蚯蚓生态毒理学测试结果的各项因素,最后对该领域未来研究提出了展望和建议。     

宁夏麻黄山草原蝗虫及天敌对土壤含水量及坡度的响应特征

为明确宁夏麻黄山蝗虫种群、天敌种群与土壤含水量及坡度之间的关系,于2012年在麻黄山蝗区设置3个样点进行2次调查,使用土壤水分温度速测仪测量不同深度土壤含水量,通过数字高程模型获取坡度数据,以网捕目测法对蝗虫及天敌进行采集,并利用典型性相关分析法分析不同深度土层土壤含水量、坡度与蝗虫物种多样性及种群密度的关系。结果显示,在能够影响蝗虫种群的20~40 cm土层上,首次调查中土壤含水量都体现出坡顶最高、坡底最低的相似趋势;第2次调查中则在不同地形上呈现出多样化。蝗虫物种多样性与20、30 cm土层含水量关系不明显,相关系数仅为0.1306和-0.0157;蝗虫种群密度与20、30 cm土壤含水量关系也不明显,相关系数为0.0077和-0.0118。随着坡度的增加,蝗虫物种多样性与种群密度都有所下降,相关系数分别为0.7223和0.4315;坡度在30°以内的蝗虫物种多样性与种群密度都比较高,超过30°后二者急剧下降。表明在西部干旱、半干旱草原地区,土壤含水量对蝗虫种群的空间分布没有决定性影响,而坡度是影响蝗虫分布的重要因素。     

黄河上游植被覆盖度空间分布特征及其影响因素

采用2000—2015年MODIS1M NDVI数据计算黄河上游年最大植被覆盖度 (FVC)，了解空间分布状况及变化特征；同时，采用了一种基于统计学原理的地理探测器模型，考虑非气候类环境因素、气候类环境因素和人类活动因素，使用相应的代理变量对黄河上游FVC空间分布的影响因素做定量研究。研究表明：① 黄河上游FVC总体上以改善为主，空间分布特征变化不大；② 单因子方面，降水量(q值0.669)是该地区FVC空间分布的主要影响因素，其他因子的影响作用存在区域差异；③ 降水分别和土壤类型、土地利用方式的交互作用(q值0.777、0.775)对研究区FVC空间分布起主导作用，土壤类型和土地利用的影响作用在一定高程、降水条件下才得以体现；④ 总体上，气候类环境因素>非气候类环境因素>人类活动因素，人类活动在与降水等环境因子的共同作用能够更充分地解释FVC空间分布；⑤ 对研究区的生态恢复应重点放在降水的充分利用和土地利用方式改进等方面。     

杀菌剂对水稻旱育秧立枯病的控制作用及其对秧苗的生理效应

为了筛选防治水稻旱育秧立枯病的有效药剂,通过秧盘试验和室内致病菌离体毒力测定,结合考察药剂对秧苗生长的影响,对保护性杀菌剂代森锰锌和福美双以及内吸治疗性杀菌剂稻瘟灵、 FDA1 霉灵等进行了系统评价。结果表明, FDA1 霉灵、甲基硫菌灵和稻瘟灵对致病菌离体毒力虽然不高,但由于 FDA1 霉灵和甲基硫菌灵对水稻秧苗生长均有促进作用,稻瘟灵能显著提高秧苗抗低温胁迫能力,这3种药剂对水稻立枯病的防治效果较好,防效达65%~81%;而离体毒力虽然高,但对秧苗生长不利的三唑酮、丙环唑和烯唑醇等三唑类药剂效果稍差,防效为51%~75%。根据试验结果提出稻瘟灵是防治该类病害的一种较理想的单用或混用药剂;针对水稻立枯病的发生受环境影响大、病原种类多等特点,指出在研究防治药剂时应采用活体筛选为主、离体筛选为辅的筛选方法,而且提倡不同杀菌谱品种的混用。     

Artificial root exudates and soil organic carbon mineralization in a degraded sandy grassland in northern China

Plant root exudates contain various organic and inorganic components that include glucose, citric and oxalic acid. These components affect rhizosphere microbial and microfaunal activities, but the mechanisms are not fully known. Studies concerned from degraded grassland ecosystems with low soil carbon（C） contents are rare, in spite of the global distribution of grasslands in need of restoration. All these have a high potential for carbon sequestration, with a reduced carbon content due to overutilization. An exudate component that rapidly decomposes will increase soil respiration and CO2 emission, while a component that reduces decomposition of native soil carbon can reduce CO2 emission and actually help sequestering carbon in soil. Therefore, to investigate root exudate effects on rhizosphere activity, citric acid, glucose and oxalic acid（0.6 g C/kg dry soil） were added to soils from three biotopes（grassland, fixed dune and mobile dune） located in Naiman, Horqin Sandy Land, Inner Mongolia, China） and subjected to a 24-day incubation experiment together with a control. The soils were also analyzed for general soil properties. The results show that total respiration without exudate addition was highest in grassland soil, intermediate in fixed dune and lowest in mobile dune soil. However, the proportion of native soil carbon mineralized was highest in mobile dune soil, reflecting the low C/N ratio found there. The exudate effects on CO2-C emissions and other variables differed somewhat between biotopes, but total respiration（including that from the added substrates） was significantly increased in all combinations compared with the control, except for oxalic acid addition to mobile dune soil, which reduced CO2-C emissions from native soil carbon. A small but statistically significant increase in pH by the exudate additions in grassland and fixed dune soil was observed, but there was a major decrease from acid additions to mobile dune soil. In contrast, electrical conductivity decreased in grassland