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11.
在2001~2002年两年间,应用百草敌、2,4-D丁酯乳油、2-甲-4-氯丙酸及混合药剂对青海大学农牧学院草业科学系试验地草坪杂草进行防除试验。结果表明:百草敌、2,4-D丁酯乳油及混合药剂I对几种主要杂草防除效果比较好,与对照相比30 d能达100%,而且两种混合药剂有增效作用,扩大了除草剂的使用范围。 相似文献
12.
Although adult Rumex obtusifolius are problematic weeds, their seedlings are poor competitors against Lolium perenne, particularly in established swards. We investigated the possibility of using this weakness to augment control of R. obtusifolius seedlings with combinations of Gastrophysa viridula (Coleoptera: Chrysomelidae) and the rust fungus Uromyces rumicis. Rumex obtusifolius seedlings were grown in competition with L. perenne sown at different rates and times after R. obtusifolius: they competed successfully with L. perenne when sown 21 days before the grass. Sowing both species at the same time resulted in a dominant grass sward, with R. obtusifolius becoming dominant when sown 42 days prior to L. perenne. Grass sowing rate had no effect on R. obtusifolius growth or biomass. A second experiment investigated how competition from L. perenne sown 21 days after R. obtusifolius combined with damage from G. viridula and/or U. rumicis (applied at either the 3–4‐ or 10–13‐leaf stage, or at both stages) affected the growth and final biomass of R. obtusifolius. Beetle grazing at the latter leaf stage was the only treatment that reduced R. obtusifolius biomass, although rust infection at the earlier application led to an increase in shoot and root weight. The results are discussed in terms of the potential for use of these agents in the field. 相似文献
13.
稻田轮作对水稻病、虫、草害的影响 总被引:2,自引:0,他引:2
目前南方大部分稻田采用连作耕作制度,并且滥用农药现象严重,这对农田生态环境造成极其不利的影响。为探讨稻田轮作对减轻稻田病、虫、草害的生态作用,本试验以长期水稻连作为对照,根据14年田间定位试验,详细研究了稻田轮作对水稻病、虫、草害的影响。结果表明,稻田轮作在一定程度上能减轻稻田水稻的病虫草害。稻田轮作处理的早稻纹枯病发病率平均比连作处理低10%,病情指数低0.4%;晚稻纹枯病的病株率平均比连作处理低17.7%,病情指数低13.3%。轮作处理的早晚稻稻曲病的病株率和病情指数也都低于连作处理。轮作处理所受虫害比连作处理要轻,轮作稻纵卷叶螟造成的白叶率和二化螟造成的白叶率明显低于连作。轮作处理的杂草生长情况比连作处理弱。 相似文献
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为了弄清南繁区转基因水稻田、非转基因水稻田和空白对照田杂草种类及发生情况,采取5点取样法,对3种田的田间杂草种类及危害情况进行了调查。结果表明:转基因水稻田有杂草19种,隶属11科,优势杂草为空心菜、牛毛毡、水莎草、莲子草、水苋菜、千金子,相对多度分别为37.58%、28.51%、26.24%、21.70%、21.62%、20.84%;非转基因水稻田主要杂草包括17种,隶属10科,优势杂草为空心菜、水莎草、牛毛毡、莲子草、水苋菜,相对多度分别为40.14%、29.83%、29.83%、24.11%、21.70%;空白对照田主要杂草包括12种,隶属8科,优势杂草为空心菜、水莎草、水苋菜、碎米莎草、莲子草、鳢肠,相对多度分别为60.28%、36.76%、34.98%、33.80%、29.11%、23.25%;水稻田(转基因水稻和非转基因水稻)中各优势杂草的危害程度明显低于空白对照;除了千金子,转基因水稻田中的优势杂草(空心菜、牛毛毡、水莎草、莲子草、水苋菜、碎米莎草、鳢肠)的危害程度均略低于对应的非转基因水稻。 相似文献
17.
M Liebman Z J Miller C L Williams P R Westerman P M Dixon A Heggenstaller A S Davis F D Menalled D N Sundberg 《Weed Research》2014,54(3):293-306
Weed seeds in and on the soil are the primary cause of weed infestations in arable fields. Previous studies have documented reductions in weed seedbanks due to cropping system diversification through extended rotation sequences, but the impacts of different rotation systems on additions to and losses from weed seedbanks remain poorly understood. We conducted an experiment in Iowa, USA, to determine the fates of Setaria faberi and Abutilon theophrasti seeds in 2‐, 3‐ and 4‐year crop rotation systems when seed additions to the soil seedbank were restricted to a single pulse at the initiation of the study. Over the course of the experiment, seedlings were removed as they emerged and prevented from producing new seeds. After 41 months, seed population densities dropped >85% for S. faberi and >65% for A. theophrasti, but differences between rotation systems in the magnitude of seedbank reductions were not detected. Most of the reductions in seedbank densities took place from autumn through early spring in the first 5 months following seed deposition, before seedling emergence occurred, suggesting that seed predation and/or seed decay was important. For S. faberi, total cumulative seedling emergence and total seed mortality did not differ between rotation systems. In contrast, for A. theophrasti, seedling emergence was 71% lower and seed mortality was 83% greater in the 3‐ and 4‐year rotation systems than in the 2‐year system. Results of this study indicate that for certain weed species, such as A. theophrasti, crop rotation systems can strongly affect life‐history processes associated with soil seedbanks. 相似文献
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Naïma Zehhar Pascal Labrousse Marie-Claire Arnaud Christian Boulet Driss Bouya André Fer 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(1):75-82
Orobanche ramosa is a parasitic Angiosperm responsible for severe yield losses in several economical crops. It is a serious threat in oilseed rape in France and Morocco and is appearing in carrot crops in Morocco. In this study, several varieties of oilseed rape and carrot were screened in order to identify resistant cultivars and to characterize the resistance mechanisms involved. All the 15 oilseed rape varieties tested were susceptible. In carrot, the varieties 'Colmar à coeur rouge' and 'Nantaise demi-longue' were susceptible, whereas 'Palaiseau' and 'Buror' were resistant. In the susceptible 'Colmar à coeur rouge' carrot no defence reactions were found and the development of the parasite inhibited carrot tap root formation. In the resistant carrot varieties, the parasite germinated, became attached to the host root but became necrotic before emergence. In 'Buror' carrot, formation of a mechanical barrier was associated with the restriction to the cortex of the parasite. In maize cv. 'Vigni', a non-host of O. ramosa, thickening of xylem vessels, cell divisions in the central cylinder and formation of an encapsulation layer were observed in association with restricted development of Orobanche haustoria. 相似文献
20.
Christopher J. Andrews Mark Skipsey Jane K. Townson Carol Morris Ian Jepson Robert Edwards 《Pest management science》1997,51(2):213-222
Using extracts from suspension-cultured cells of soybean (Glycine max cv. Mandarin) as a source of active enzymes, the activities of glutathione transferases (GSTs) catalysing the conjugation of 1-chloro-2,4-dinitrobenzene (CDNB) and selective herbicides were determined to be in the order CDNB≫ fomesafen>metolachlor=acifluorfen>chlorimuron-ethyl. GST activities showed a thiol dependence in a substrate-specific manner. Thus, GST activities toward acifluorfen and fomesafen were greater when homoglutathione (hGSH), the endogenously occurring thiol in soybean, was used as the co-substrate rather than glutathione (GSH). Compared with GSH, hGSH addition either reduced or had no effect on GST activities toward other substrates. In the absence of enzyme, the rates of hGSH conjugation with acifluorfen, chlorimuron-ethyl and fomesafen were negligible, suggesting that rapid hGSH conjugation in soybean must be catalysed by GSTs. GST activities were subsequently determined in 14-day-old plants of soybean and a number of annual grass and broadleaf weeds. GST activities of the plants were then related to observed sensitivities to post-emergence applications of the four herbicides. When enzyme activity was expressed on a mg-1 protein basis, all grass weeds and Abutilon theophrasticontained considerably higher GST activity toward CDNB than soybean. With fomesafen as the substrate, GST activities were determined to be in the order soybean≫Echinochloa crus-galli>Digitaria sanguinalis>Sorghum halepense=Setaria faberi with none of the broadleaf weeds showing any activity. This order related well to the observed selectivity of fomesafen, with the exception of A. theophrasti, which was partially tolerant to the herbicide. Using metolachlor as the substrate the order of the GST activities was soybean>A. theophrasti≫S. halepense>Amaranthus retroflexus>Ipomoea hederacea, with the remaining species showing no activity. GST activities toward metolachlor correlated well with the selectivity of the herbicide toward the broadleaf weeds but not toward the grass weeds. Acifluorfen and chlorimuron-ethyl were selectively active on these species, but GST activities toward these herbicides could not be detected in crude extracts from whole plants. © 1997 SCI 相似文献