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81.
A field study was conducted in 2001 and 2002 at Blackville, SC, to evaluate broadleaved weed control and economics of conventional and glyphosate-containing herbicide programmes in glyphosate-resistant soybean planted in 97-cm-wide rows. Treatments included chlorimuron plus sulfentrazone or chlorimuron plus metribuzin applied pre-emergence followed by post-emergence applications of lactofen or glyphosate 4 wk after soybean emergence (WAE). Other treatments were glyphosate applied 4 WAE, sequential applications of low dose glyphosate applied 2 and 4 WAE, and a non-treated control. Pre-emergence herbicides followed by glyphosate, controlled Ipomoea lacunosa L. 8 WAE. I. hederacea var. integriuscula Gray control with pre-emergence herbicides followed by glyphosate was 100% with similar control from chlorimuron plus sulfentrazone followed by lactofen, whereas control following the single glyphosate application was 84%. Amaranthus palmeri S. Wats. control 9 WAE was 100% following single or sequential glyphosate applications, while control ranged from 76% to 96% with pre-emergence herbicides followed by lactofen. However, early season weed interference when a single application of glyphosate was delayed until 4 WAE reduced soybean yields an average of 389 kg/ha compared to pre-emergence herbicides followed by glyphosate. Based on mean contrasts, pre-emergence herbicides followed by glyphosate had greater gross profit margins than a single glyphosate application alone, but were similar to sequential glyphosate applications. Gross profit margins from pre-emergence herbicides followed by lactofen were not different from glyphosate alone. 相似文献
82.
From their introduction in 1996, glyphosate resistant (GR) soybean cultivars have been rapidly adopted by farmers in Argentina and in other countries in the world. The high rate of adoption of this technology seems to be based on the simplicity of use provided by a single herbicide (glyphosate), its high efficacy to control many weeds and, the low costs of the technology relative to that used in conventional crops. During 2001–2002, 2002–2003 and 2003–2004 soybean growing seasons, field surveys and field experiments were performed with the aim of studying the effect of different glyphosate management strategies on the diversity of soybean weed communities, weed control, individual survival, fecundity and crop yield. In addition, the emergence pattern of three important weeds, Digitaria sanguinalis, Cyperus rotundus and Anoda cristata, was also studied. Both field surveys and field experiments were carried out on no-till soybean crops sown immediately after wheat or barley harvest (double cropped system). Experiments were set up in commercial soybean crops and consisted of different times of a single glyphosate application, two glyphosate applications and also the application of glyphosate plus a residual herbicide imazethapyr. A. cristata, D. sanguinalis, Stellaria media, Chenopodium album and Cyperus sp. were the most prevalent weeds recorded at pre-harvest of the soybean crops, showing regional constancy higher than 80% in both years. In three out of four field experiments, crop yield was not increased when glyphosate was applied twice compared with a single application of the herbicide. In addition there was a lower negative effect on weed species richness when glyphosate was applied once during the crop cycle than with two applications of glyphosate or glyphosate plus imazethapyr. D. sanguinalis escaped the glyphosate early treatment because of the long weed emergence period, while A. cristata and C. rotundus survived treatments due to their high individual tolerance. The results suggest that it is possible to manage glyphosate application to get high crop yield with a low impact on weed diversity, depending on the weed species and their abundance. 相似文献
83.
草甘膦对土壤微生物的影响 总被引:2,自引:0,他引:2
以东北地区黑土为材料,探讨草甘膦对土壤呼吸、土壤可培养菌种群数量、大豆固氮根瘤菌和大豆根腐镰刀菌数量的影响。研究结果表明,随着草甘膦浓度的加大,土壤呼吸的抑制作用增强,土壤中草甘膦含量为1 mg&;#8226;kg-1、10 mg&;#8226;kg-1、100 mg&;#8226;kg-1时,危害系数分别为1.20、0.322、0.0760,远小于无危害标准系数20,确定草甘膦对土壤微生物低毒或无实际危害。不同浓度的草甘膦对土壤真菌、放线菌种群数量具有一定影响。土壤可培养菌种群数量随草甘膦浓度的升高抑制作用逐渐增强,随着草甘膦加入时间的延长,真菌、细菌、放线菌的种群数量有所恢复,其中放线菌与真菌同细菌相比对草甘膦敏感,土壤细菌对草甘膦具有较强的耐受或降解能力。草甘膦对大豆根瘤菌和大豆根腐镰刀菌有一定影响,对大豆根瘤菌的抑制作用与草甘膦浓度呈正比;低浓度草甘膦对镰刀菌产生激活作用,高浓度草甘膦对镰刀菌具有抑制作用;伴随草甘膦加入时间的延长,其对大豆根瘤菌和大豆根腐镰刀菌的抑制作用逐渐减弱。 相似文献
84.
Tertyllianos MitsisAspasia Efthimiadou Dimitrios J. Bilalis Nicholas G. DanalatosPanagiotis Efthimiadis Aristidis Konstantas 《Industrial Crops and Products》2011,33(2):544-548
Adverse hot and dry environmental conditions prevailing during the period of oilseed rape ripening can be blamed for considerable yield losses during the crop's mechanized harvesting in the Mediterranean area. In this paper, the effect of chemical dessication of oilseed rape with glyphosate applied 35 days after anthesis for reducing seed yield loss was studied. The experiment was conducted in four fields at two locations in central Greece and for two growth periods following a completely randomized plot design with 8 treatments in three replications. Treatments include all possible combinations of two crop varieties and four levels of glyphosate (as dessicant) application. A significant positive effect of dessicant application level on crop yield for both studied varieties was found. The application dose of 200 g a.i. of glyphosate per hectare had the best results. The highest dry weight was found among the plants sprayed with 200 g. a.i. of glyphosate per hectare. The highest seed yield and oil yield were found among the plants sprayed with 200 g a.i. per hectare, which makes clear the positive effect of this spraying minimizing pod shattering and yield losses. The greatest 1000-seed weight was found among the plants sprayed with 200 g a.i. ha−1, due to the greater size of seeds that remained on the plants until harvesting. 相似文献
85.
Sanja Baric Christine Kerschbamer Josef Vigl Josef Dalla Via 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(2):207-211
Apple proliferation (AP), a phytoplasma-induced disease of apple trees, was proven to be transmitted through infected grafting
material and sap-sucking insects. To date there are little firm data on disease propagation in the field via natural root
grafts. This question was thus addressed in the present case study by investigating trees of a 24-year old commercial apple
orchard (‘Red Chief’ on MM 111), where the existence of root connections was discovered accidentally. After having displayed
specific AP symptoms, nine trees were cut down and the stubs were infiltrated or brushed with glyphosate. Herbicide injury,
however, remained not only restricted to the treated stubs, but also spread to approximately 50 neighbouring trees. Surprisingly,
none of the pollinators (‘Granny Smith’ on M 9) growing interjacently and alternating between herbicide-damaged main crop
trees was affected. Respective to the position of the nine AP-infected and glyphosate-treated cut stumps, four sections in
the orchard were defined, from which a total of 122 trees was sampled and analysed using qualitative real-time PCR for detection
of AP phytoplasma. The pathogen was found in 71.4% of ‘Red Chief’ trees with severe herbicide damage and 18.8% of trees with
partial herbicide damage. None of the 31 investigated pollinators was AP-infected. Our data indicate that root connections
seem to play a role for the spread of AP phytoplasma at least in older orchards and between trees on vigorous rootstocks. 相似文献
86.
B.V. Ortiz S.J. ThomsonY. Huang K.N. ReddyW. Ding 《Computers and Electronics in Agriculture》2011,77(2):204-213
Crop injury caused by off-target drift of herbicide can seriously reduce growth and yield and is of great concern to farmers and aerial applicators. Farmers can benefit from identifying an indirect method for assessing the level of crop injury. This study evaluates the combined use of statistical methods and vegetation indices (VIs) derived from multispectral images to assess the level of crop injury. An experiment was conducted in 2009 to determine glyphosate injury differences among the cotton, corn, and soybean crops. The crops were planted in eight rows spaced 102 cm apart and 80 m long with four replications. Seven VIs were calculated from multispectral images collected at 7 and 21 days after the glyphosate application (DAA). At each image collection date, visual injury estimates were assessed and data were collected for plant height, chlorophyll content, and shoot dry weight. From the seven VIs evaluated as surrogate for glyphosate injury identification using a canonical correlation analysis (CCA), the Chlorophyll Vegetation Index (CVI) showed the highest correlation with field-measured plant injury data. CVI image values were subtracted from the CVI average values of the non-injured area to generate CVI residual images (CVIres). Frequency distribution histograms of CVIres image values were calculated to assess the level of injury between crops. These data suggested that injury increased from 7DAA to 21DAA with corn exhibiting higher severity of injury than cotton or soybean, while only moderate injury was observed for cotton. The techniques evaluated in this study are promising for estimating the level of glyphosate herbicide drift, which can be used to make appropriate management decisions considering crop proximity. 相似文献
87.
用耐性菜豆根尖为材料,以λgt10为载体获得了4.8×105个重组噬菌体的cDNA文库。以植物EPSP合成酶基因保守序列合成二段探针,经噬菌体原位杂交筛选出了阳性克隆,并进行了酶切鉴定。测定 cDNA 序列长度为2024个核苷酸,其中编码长1569个核苷酸,共编码523个氨基酸和一个终止密码子,与已发表的其它植物成熟EPSP合成酶氨基酸序列相比具有很高的同源性(≥84.8%),但进入叶绿体运输肽的氨基酸同源性低。以耐性菜豆EPSP合成酶的cDNA序列为模板,用RT-PCR方法扩增感性菜豆EPSP合成酶cDNA片段,并克隆于pUC18质粒上,经测定序列并比较发现:感性菜豆EPSP合成酶cDNA核苷酸序列1737位碱基为G,而耐性的为C,从而表达出的513位氨基酸残基感性的为E,耐性的为Q,表明两种菜豆EPSP合成酶cDNA核苷酸序列一位点的差异是它们对草甘膦耐性不同的原因。 相似文献
88.
Glyphosate efficacy was examined in young velvetleaf plants from the standpoint of its tissue distribution and sensitivity. In whole plant assays, manual application of a sub-lethal dose to the first leaf resulted only in meristem injury while other tissues remained visually healthy. Our studies showed that this differential tissue response was caused by a combination of differential distribution as well as sensitivity to glyphosate. Using [14C]glyphosate, we measured tissue injury and glyphosate residue, and calculated tissue threshold for 50% growth inhibition. Our studies showed that roots and meristem have high glyphosate distribution (45 and 34% of translocated, respectively) and low inhibition thresholds (0.23 and 0.21 ppm, respectively) resulting in tissues that were easily killed by glyphosate. In contrast, the base stem contained a much higher inhibition threshold (8.4 ppm) with only intermediate distribution (10%) resulting in a tissue that was most difficult to kill. We observed a linear relationship between glyphosate dose and tissue concentration; furthermore, tissue distribution pattern was independent of dose or surfactants class. At a sub-lethal dose, sensitive tissues that received a large distribution of glyphosate were preferentially killed. As the dose was increased, more glyphosate was available for distribution, and all tissues received a proportionately greater amount of glyphosate. Plant death occurred when the applied dose was sufficient to attain the lethal threshold in all tissues. 相似文献
89.
90.
铜和草甘膦对蚯蚓的毒性效应研究 总被引:2,自引:1,他引:2
污染物的交互作用及其生态毒理效应已成为环境科学研究的主要方向。含铜杀菌剂与除草剂草甘膦[N-(膦酸甲基)甘氨酸]是农业生产中常见的农药,其在土壤中共存可能造成复合污染。草甘膦中含有羧基、氨基、磷酸基等配位基团对重金属阳离子和有机阳离子有很强的络合能力,草甘膦可以影响重金属的生物有效性、毒性以及重金属在生物体内的积累。本文以赤子爱胜蚓(Eisenia fetida)为例,采用室内模拟试验,单一试验设置5个铜浓度25 mg·kg-1、50 mg·kg-1、100 mg·kg-1、200 mg·kg-1和400 mg·kg-1,5个草甘膦浓度25mg·kg-1、50 mg·kg-1、100 mg·kg-1、200 mg·kg-1和500 mg·kg-1,并以去离子水做空白对照;复合试验设置2个铜浓度(低铜浓度25 mg·kg-1和高铜浓度200 mg·kg-1)分别与5个草甘膦浓度(0、25 mg·kg-1、50 mg·kg-1、100 mg·kg-1和200 mg·kg-1)复合;每个处理3次重复,试验期为35 d。研究了铜和草甘膦的单一及复合施用对蚯蚓的亚急性毒性效应。单一毒性试验结果表明,蚯蚓对低浓度铜的响应不敏感,而较高浓度铜使蚯蚓生物量的相对增长率受到显著抑制(α=0.01,r2=0.570),且未出现死亡,并且随着铜浓度的增加蚯蚓体内铜含量显著增加(α=0.01,r2=0.905)。与对照相比草甘膦的添加对蚯蚓的生长无显著影响。复合毒性试验结果表明,草甘膦和铜复合可以降低蚯蚓对铜的吸收,特别是当铜浓度较高时即200 mg·kg-1,草甘膦和铜复合可显著降低蚯蚓对铜的吸收,并且草甘膦能够减轻铜对蚯蚓生物量相对增长率的抑制,但差异并不显著。以上结果表明,铜比草甘膦的毒性大很多,铜与草甘膦复合能够减少蚯蚓对铜的吸收,缓解铜的毒性。因此本研究认为,在草甘膦和重金属共存的污染土壤中,草甘膦能够控制重金属的生物有效性和毒性。 相似文献