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P K JENSEN 《Weed Research》2009,49(6):592-601
Persistence of seeds of the four winter annual grass species, Alopecurus myosuroides , Bromus sterilis , Bromus hordeaceus and Vulpia myuros , were studied under field conditions. The studies also included the two dicotyledon species, Tripleurospermum inodorum and Galium aparine . Seed samples were stored in the field at different depths in the plough layer for a year. Following germination, seedling emergence was taken as an indicator of field persistence. In a supplementary investigation, seed samples were placed on the soil surface or buried at 2 cm for a month and then tested for viability. Persistence of the two Bromus species was very short, irrespective of depth and duration of burial. Persistence of the other species was positively correlated with incorporation of seeds to a few centimetres depth. Increasing the depth of incorporation below 2 cm had a variable influence on persistence. Persistence of seeds placed directly on the soil surface was short, whether they were left there for a year or a month. Whether seeds at the soil surface were left uncovered or covered with chopped straw had limited influence on seed persistence. However, straw cover significantly increased persistence of A. myosuroides seeds and there was the same tendency with T. inodorum . 相似文献
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[目的]研究贯叶连翘提取物(HPE)对流感病毒感染小鼠肺组织中肿瘤坏死因子(TNF-α)、γ-干扰素(IFN-γ)等细胞因子的影响。[方法]以流感病毒滴鼻感染小鼠,分别灌胃给药(贯叶连翘提取物高剂量组100 mg/kg、低剂量组50 mg/kg和病毒唑组10 mg/kg),0.2ml/次,2次/d,5 d后摘眼球放血处死动物,摘出全肺,低温条件下制成肺匀浆,离心后取上清采用双抗体夹心ELISA法观察小鼠治疗前后肺组织中IFN-γ、TNF-α的变化。[结果]与模型对照组相比,贯叶连翘提取物流感病毒感染小鼠肺组织中TNF-α显著降低(P<0.05),IFN-γ极显著升高(P<0.01)。[结论]贯叶连翘提取物对机体抗感染免疫有一定调节作用。 相似文献
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贯叶连翘不定根悬浮培养的初步研究 总被引：1，自引：1，他引：0
为了给贯叶连翘不定根的大量扩繁提供可靠的理论依据,以贯叶连翘不定根为材料进行悬浮培养,对不定根生长的培养基种类、糖种类以及IBA浓度进行优化筛选,再通过观察贯叶连翘不定根的生长情况,测量其鲜物重和干物重,计算干物率和增殖系数,来确定最佳的悬浮培养条件。不同的培养基种类对贯叶连翘不定根的生长影响较大,MS对促进不定根生长的效果最好;蔗糖可明显增加贯叶连翘不定根的鲜物重和干物重,分别为8.29 g、0.46 g;当IBA浓度为1.0 mg/L时,贯叶连翘不定根的鲜物重﹑干物重﹑干物率以及增殖系数均达到最大值,分别为8.98 g﹑0.49 g﹑5.46%和13.97。贯叶连翘不定根在MS+IBA 1.0 mg/L,蔗糖作为其碳源的悬浮培养基中生长,增殖效果最好。 相似文献
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贯叶金丝桃的电子束辐照杀菌研究 总被引：1，自引：1，他引：0
研究电子束辐照贯叶金丝桃杀菌的可行性,为科研和生产中有效地应用该方法提供理论依据。辐照样品中微生物数量的测定依据《中华人民共和国药典》提供的方法;应用高效液相色谱检测有效成分金丝桃素和金丝桃苷含量;依据微生物存活对数与辐照剂量的线性关系,求得D10;采用目测、鼻嗅、品尝的评定方法,评定样品辐照前后的外部性状变化。结果表明:细菌、霉菌+酵母菌的D10值分别为2.91 kGy和4.69 kGy,霉菌和酵母菌相对于细菌对电子束有更强的耐受力,适宜的辐照加工剂量为4.5~6.5 kGy,经过辐照后,样品可以保存30~150 d,卫生指标仍达到国家药典中规定的中药粉剂微生物限度标准,金丝桃苷和金丝桃素的含量未发生显著变化。因此,利用电子束辐照贯叶金丝桃杀菌是一种行之有效的方法。 相似文献
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Using a competition model to quantify the optimal trade-off between machine vision capability and weed removal effectiveness 总被引：1，自引：1，他引：0
A C GRUNDY C M ONYANGO† K PHELPS R J READER J A MARCHANT† L R BENJAMIN‡ & A MEAD 《Weed Research》2005,45(5):388-405
The algorithm of an optical detection system was first investigated for its ability to correctly classify transplanted crops and weeds during the critical early stages of crop establishment and its robustness over a range of different crop species. The trade-off was then examined between increasing the sensitivity of the detection system vs. the possibility of, in doing so, misclassifying some crop plants as weeds and inadvertently removing them. This was achieved by running a competition model using parameters derived from the image analysis and assessing the outcome of scenarios in terms of yield. The optimum parameter values to maximize the detection of the crop and the optimum parameter values to maximize the detection of the weed appeared relatively insensitive to time of image capture or weed density. They also appeared insensitive for different crop species where the crop had similar growth habit. However, competition scenarios indicated that the detection system parameter settings to achieve optimum yields were sensitive to the competitive ability of the weed species. For Veronica persica, crop yield was more sensitive to accidental crop removal than from competition. In contrast, in the presence of Tripleurospermum inodorum, yield loss was more attributable to weed competition. Importantly, linking the detection system with the competition model illustrated the principle that optimum yield may not necessarily be obtained by maximizing weed removal or minimizing crop removal. This first example of combining a detection system with a competition model presents a new opportunity to quantify the sensitivity of image classification in terms of yield. 相似文献
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以贯叶连翘粗提浸膏为材料,考察六种大孔吸附树脂分离纯化金丝桃素的性能。采用静态、动态吸附方法筛选树脂,以中压分离方法确定分离纯化的条件。结果表明:HZ-801树脂以其高吸附率、高洗脱率成为优选的分离填料,其最佳分离纯化条件为:进样液质量浓度为0.1125 g/m L,进样速度为5.0 m L/min、洗脱速度为20 m L/min,0~95%乙醇溶液梯度洗脱,金丝桃素的纯度为79.11%。HZ-801可以较好分离纯化金丝桃素,纯化工艺具有较大实践性及参考价值。 相似文献
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The development of acetolactate synthase (ALS) tolerant sugar beet provides new opportunities for weed control in sugar beet cultivation. The system consists of an ALS?inhibiting herbicide (foramsulfuron + thiencarbazone‐methyl) and a herbicide‐tolerant sugar beet variety. Previously, the use of ALS‐inhibitors in sugar beet was limited due to the susceptibility of the crop to active ingredients from this mode of action. The postulated benefits of cultivation of the ALS‐tolerant sugar beet are associated with potential risks. Up to now, with no relevant proportion of herbicide‐tolerant crops in Germany, ALS‐inhibitors are used in many different crops. An additional use in sugar beet cultivation could increase the selection pressure for ALS‐resistant weeds. To evaluate the impact of varying intensity of ALS‐inhibitor use on two weed species (Alopecurus myosuroides and Tripleurospermum perforatum) in a crop rotation, field trials were conducted in Germany in two locations from 2014 to 2017. Weed densities, genetic resistance background and crop yields were annually assessed. The results indicate that it is possible to control ALS‐resistant weeds with an adapted herbicide strategy in a crop rotation including herbicide‐tolerant sugar beet. According to the weed density and species, the herbicide strategy must be extended to graminicide treatment in sugar beet, and a residual herbicide must be used in winter wheat. The spread of resistant biotypes in our experiments could not be attributed to the integration of herbicide‐tolerant cultivars, although the application of ALS‐inhibitors promoted the development of resistant weed populations. Annual use of ALS‐inhibitors resulted in significant high weed densities and caused seriously yield losses. Genetic analysis of surviving weed plants confirmed the selection of ALS‐resistant biotypes. 相似文献
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针对目前国际上日渐重视金丝桃素的应用情况，建立了简单的高效液相色谱(HPLC)测定野生及栽培的贯叶连翘提取物中金丝桃素的含量，回收率分别为98．6％和97．2％，相对标准偏差分别为1．2％和1．6％(n=4)。该法灵敏度高，最小检出量低，有良好的重现性和精密度。 相似文献
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[目的]建立贯叶连翘的ISSR-PCR反应体系,并对其条件进行优化.[方法]以贯叶连翘基因组DNA为模板,用L16(45)正交试验设计系统分析引物浓度、Taq DNA聚合酶浓度、Mg2浓度、dNTP浓度和模板DNA浓度5种因素对贯叶连翘ISSR-PCR反应扩增结果的影响.[结果]正交试验设计的方法可以用于贯叶连翘1SSR-PCR反应体系的建立,经过优化得到贯叶连翘ISSR-PCR反应体系的最佳条件为:20μISSR-PCR反应体系中含10×PCR buffer,Mg2+浓度1.2 mmol/L,Taq DNA聚合酶浓度50 U/ml,DNA浓度20 ng/μl,dNTP浓度250 μmol/L,引物浓度0.75 μmol/L.[结论]试验建立的贯叶连翘的ISSR-PCR反应体系重复性好、分辨率高,结果稳定可靠. 相似文献