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Field experiments were conducted to characterize the demography of Abutilon theophrasti and Setaria faberi in a conventionally managed 2‐year (maize/soya bean) rotation, and in 3‐year (maize/soya bean/triticale + red clover) and 4‐year (maize/soya bean/triticale + lucerne/lucerne) rotations managed with 72% and 79% lower herbicide inputs respectively. Rates of weed seedling recruitment, seedling survival and adult plant fecundity were determined for populations in each phase of each rotation and used to calculate annual rates of weed population change, Δ. In both years of the study, Δ for A. theophrasti populations declined or remained stable in all three rotation systems. Despite greater rates of seedling survival and fecundity in maize and soya bean in the 3‐ and 4‐year rotations, increases in Δ for A. theophrasti populations were prevented in these systems because of low fecundity in triticale and low seedling survival and fecundity in lucerne. For Setaria faberi populations, Δ remained stable in the 2‐year rotation, increased in the 3‐year rotation in both years, and increased in the 4‐year rotation in 1 year. The results of this study indicate that when herbicide use is reduced, rotations that include triticale and lucerne can facilitate the suppression of A. theophrasti. Rotations that include lucerne can contribute to restraining S. faberi population growth, given adequate levels of seedling mortality in this crop. 相似文献
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Soil nitrogen (N) is considered an important driver of crop‐weed interactions, yet the mechanisms involved have been only partially explored, especially with respect to early‐season growth, when competitive hierarchies are formed. This study characterises the effects of different N levels on biomass accumulation and plant morphology for maize (Zea mays), and four important weed species (Amaranthus retroflexus, Abutilon theophrasti, Setaria faberi, and Chenopodium album). Under glasshouse conditions, plants were grown in separate pots and irrigated with nutrient solution at four N concentrations (0.2, 0.5, 2, 5 μm L−1) until 57 days after emergence. Except for S. faberi, which was unresponsive to N, the relative biomass growth rates (RGR) of maize and the broad‐leaved weeds were positively and similarly affected by increasing nitrogen. At all N levels, maize had a height advantage by virtue of its larger seed size, which conferred early growth benefits independent of RGR. At low N, biomass growth was instrumental to S. faberi’s improved competitive position, whereas height development per unit biomass improved the competitive position of A. theophrasti, C. album and A. retroflexus. The approach presented could be applied to other crop‐weed systems to evaluate environmental impacts on competitive outcomes. 相似文献
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Setaria faberi and Digitaria ciliaris are summer annual grass weeds that constitute an orchard weed community in Japan. Species dominance in the weed community shifts from S. faberi to D. ciliaris with an emergence delay. The change in species dominance is assumed to be a clue to how weeds dominate or coexist in shaping the community. Population dynamics and seasonal variations in emergence and competitive ability were studied from this viewpoint. Field monitoring and pot experiments exhibited that the emergence period of the two species overlapped extensively from April to June. The emergence of S. faberi began 2 weeks earlier than that of D. ciliaris in April and declined in June as a result of the induction of secondary dormancy. The plant density of D. ciliaris was high during the whole period. The great mortality of the species was replenished with its great natality. The replacement series experiments revealed that S. faberi that had been planted in April was a better competitor than D. ciliaris, but it lost its competitive superiority in the June plantings, when D. ciliaris became a superior competitor to S. faberi. The level of seed output was greater for D. ciliaris, even when it was an inferior competitor. Therefore, the shift in species dominance appeared to be attributed to a change in competitive superiority between the two species. The early emergence of S. faberi and the high plant density of D. ciliaris might accelerate competitive exclusion. The two species coexist when they are equivalent in competitiveness. 相似文献
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月月红中槲皮素·山奈酚的定性与定量研究 总被引：1，自引：1，他引：0
[目的]通过对月月红中槲皮素、山奈酚的定性定量研究,拟建立其HPLC分析方法,为进一步研究民族民间药物月月红的药效学奠定基础。[方法]采用化学定性法确定月月红不同部位中的主要化学组分;色谱条件：Hypersil DJZ C18色谱柱（4.6 mm×200.0 mm,5μm）;流动相：甲醇-0.4%磷酸（60∶40,V/V）;检测波长：368 nm;流速：1.000 ml/min;柱温：30℃;理论塔板数按山奈酚和槲皮素峰计算不低于3 000,外标法计算。[结果]槲皮素在0.081 6~0.489 6μg线性关系良好（R2=0.999 6）,平均回收率为101.6%,RSD为0.87%;山奈酚在0.069 6~0.417 6μg线性关系良好（R2=0.999 6）,平均回收率为96.8%,RSD为1.01%。月月红叶中槲皮素为0.038 2%,茎为0.005 2%,全株为0.010 5%;月月红叶中山奈酚含量为0.027 6%,茎为0.002 1%,全株为0.009 6%。[结论]HPLC分析方法稳定、重复性较好;月月红不同部位均含有槲皮素、山奈酚,且叶含量高于全株和茎。 相似文献
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春荷鼎杂交根状茎的组培快繁的研究 总被引：2，自引：1，他引：1
摘要：【研究目的】本文采用传统品种春荷鼎与普通春兰杂交的继代根状茎为试材,对根状茎的增殖和分化进行研究。【方法】探讨不同培养基、转换培养基、6-BA与NAA、IBA对根状茎增殖、分化的影响。【结果】不同培养基对生长率有明显影响,1/2 MS为春兰根状茎的基本培养基;最适增殖培养基为1/2 MS+BA0.1+NAA0.1;根状茎的最佳分化培养基为1/2 MS+BA1.0+IBA1.0;以1/2 MS+BA1.0+IBA1.0培养基再转入B5+BA1.0+IBA1.0培养得交替培养方式,获得分化率达76%。【结论】组培快繁是培育春兰新品种的重要技术手段。 相似文献
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本文利用FTIR技术分别检测不同产地紫金牛及其易混淆植物的化学成分的光谱特征,并通过主成分分析模型以及主成分载荷因子等化学计量学方法,对各样本进行鉴别,找出各测试样本化学组成的差异。结果表明：f1）两种紫金牛在3378cm^-1、2923cm^-1、1735cm^-1、1621cm^-1、1444cm^-1、1373cm^-1、1321cm^-1、1238cm^-1、1153cm^-1、1033cm^-1及776cm^-1附近均有吸收峰。（21由于融水县和永福县两地相距最近,在PCA检测模型二维散点图上,这两产地样品的距离也最近,恭城县与融水县及广西兴安县相距较远,故在散点图上的距离也较远;广西兴安县的月月红是紫金牛属植物,但不属于紫金牛种,所以,在散点图上的距离也就偏离各产地紫金牛。（3）提取PCA模型的载荷因子,分析表明,在种问比较,样品月月红中脂类、苯醌、黄酮及皂苷类成分的含量较紫金牛样品丰富。在紫金牛种内比较,广西永福县的样品香豆素、酮脂及皂苷类成分的含量比其它产地高,相反地,广西恭城药市的样本中尤其是酮脂及皂苷类成分的含量最低;但是,广西恭城县的紫金牛中香豆素、苯醌、甾醇,黄酮类等成分,较其它产地丰富。 相似文献
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杂交兰原球茎增殖及分化研究 总被引：4，自引：0，他引：4
[目的]对杂交兰原球茎的增殖及分化进行研究。[方法]采用L9(34)正交试验设计,研究培养基、6-BAI、BA和AC对杂交兰原球茎增殖的影响;设置几种不同培养基对原球茎的分化进行探讨。[结果]培养基和6-BA对原球茎的增殖影响不大,IBA浓度为0.1 mg/L、AC浓度为1.0 mg/L时,原球茎增殖效果最好;1/2 MS+6-BA 1.0 mg/L+NAA 0.5 mg/L对原球茎的分化效果最好。[结论]在培养基中添加NAA有利于原球茎的分化。 相似文献
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C L WILLIAMS M LIEBMAN P R WESTERMAN† J BORZA D SUNDBERG & B DANIELSON‡ 《Weed Research》2009,49(4):439-447
To improve understanding of over-winter weed seed predation in arable fields, we used data from winter exclosure trials to determine the amount of predation and the influence of crop habitats on predation of Abutilon theophrasti and Setaria faberi seed in 2-year (maize/soyabean) and 4-year (maize/soyabean/small grain+lucerne/lucerne) crop rotation systems between 2005 and 2008. Crop habitat influenced seed predation, and had similar impacts on the two weed species. Mean A. theophrasti predation ranged from 31% in the 2-year soyabean habitat to 99% in the 4-year lucerne habitat. Mean S. faberi predation ranged from 31% in the 2-year soyabean habitat to 97% in the 4-year lucerne habitat. Results suggest that a combination or interaction of cover and substrate may have affected crop habitat preference by seed predators. Future research should further examine the influence of physical habitat on seed predation to determine characteristics of cropping systems that encourage predation, particularly during over-winter periods, so as to routinely incorporate seed predators into long-term weed management strategies. 相似文献
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[目的]探讨杂交兰（Cymbidium hybridum×faberi）组培快繁技术,为杂交兰的工厂化生产提供技术支撑.[方法]以杂交兰茎尖和腋芽为外植体,调查不同激素与活性炭（AC）组合对原球茎诱导、增殖分化和生根培养的影响.[结果]6-BA是影响原球茎诱导的主要因素,IBA是影响原球茎增殖和分化的主要因素.原球茎诱导和增殖最适培养基为MS＋6-BA 1.0 mg/L＋IBA 0.5 mg/L＋AC 3.0 g/L＋3％蔗糖;MS＋6-BA 0.5 mg/L＋IBA 0.5 mg/L＋AC 3.0 g/L＋3％蔗糖最适于原球茎分化成苗;壮苗生根培养基为1/2MS＋ IBA 0.5 mg/L＋AC 1.0 g/L＋3％蔗糖＋0.5％琼脂.[结论]在MS基本培养基中,低量的6-BA、IBA对杂交兰原球茎诱导、增殖与分化、生根和移栽成活均有明显促进效应,原球茎不同生长阶段对AC的需求量不同. 相似文献