高锰胁迫下草甘膦对空心莲子草体内莽草酸含量和抗氧化酶活性的影响

鉴于高锰胁迫下空心莲子草Alternanthera philoxeroides对草甘膦的耐药性增强,在水培条件下研究了不同浓度锰条件下草甘膦处理后该草体内莽草酸的积累和主要抗氧化酶系统的响应。次高浓度锰(0.31 mmol/L)条件下培养120 d后空心莲子草体内过氧化氢酶(CAT)活性显著高于常规浓度锰处理(0.009 1 mmol/L,对照);高浓度锰(2.45 mmol/L)条件下超氧化物歧化酶(SOD)活性升高,CAT活性下降。草甘膦(按草甘膦酸68 g/hm2)茎叶处理后6 d内,常规锰浓度培养的空心莲子草体内莽草酸含量比用草甘膦刚处理时增加了31.9％~226.0%,且显著高于同一时间次高锰和高锰的处理;不同锰浓度下培养的空心莲子草体内过氧化物酶(POD)和CAT、SOD活性均为先升高后再逐渐下降,但次高锰处理的该3种酶活性均高于对照,高锰处理的SOD和POD活性高于对照,而CAT活性与对照相当。上述结果表明,在较高锰浓度下空心莲子草能启动抗氧化酶系统而能有效地清除自由基;在草甘膦处理后初期,高锰条件下空心莲子草体内莽草酸途径受抑制程度较轻,抗氧化酶活性较高,这可能是空心莲子草耐高锰和高锰条件下该草耐草甘膦的部分机制。     

草甘膦对田旋花和打碗花体内莽草酸含量的影响

草甘膦处理后14d,对田旋花、打碗花、大豆体内莽草酸积累量进行分析,可明确田旋花和打碗花对草甘膦的敏感性.草甘膦840ga.i./hm2、420ga.i./hm2处理后,不同植物体内莽草酸的积累量依次为大豆>打碗花>田旋花.田旋花对草甘膦的耐药能力最强,并且随着生长时间的延长对草甘膦的抗药能力增强.打碗花只是在草甘膦剂量比较低时具有一定的耐药能力.     

三种杂草对草甘膦的敏感性及处理后植株体内莽草酸积累量差异

为明确不同杂草对草甘膦的敏感性,以稗 Echinochloa crusgalli 、马唐 Digitaria sanguinalis 、藜 Chenopodium album 为供试材料,采用生物测定法和吸光光度法分别测定了草甘膦对3种杂草的抑制中浓度(GR50),以及不同剂量处理后杂草体内莽草酸积累量的变化。经410 g/hm2(有效成分)的草甘膦处理后,稗体内莽草酸积累量呈上升-下降-上升趋势,而马唐和藜则表现为缓慢上升,根据此剂量处理下莽草酸积累趋势得出,3种杂草对草甘膦的敏感性由高到低依次为稗、藜和马唐,与生测法的结果一致。经820~3 280 g/hm2(有效成分)的草甘膦处理后,3种杂草体内莽草酸积累量从第2 d开始急剧升高,增长速率随着草甘膦处理剂量的增加而加大;处理后稗、马唐和藜体内莽草酸积累量最高值差异显著,分别为1 137.9、4 989.7和2 084.2 μ g/g,为各自对照水平的16.7、23.7和82.9倍。该研究结果可为系统检测杂草对草甘膦的敏感性提供依据。     

甲磺隆和草甘膦对空心莲子草乙酰乳酸合酶活性和莽草酸含量的影响

为研究甲磺隆和草甘膦对空心莲子草的作用机理,探索其最佳的使用技术,采用有效成分为30 g/hm2和60 g/hm2 的甲磺隆处理空心莲子草,能明显抑制其茎和根乙酰乳酸合酶的比活性;有效成分为1537.5g/ hm2和3075g/ hm2 的草甘膦处理则能明显抑制空心莲子草莽草酸含量的积累;施用甲磺隆和草甘膦对空心莲子草生长的抑制作用随药剂浓度的提高而增大.二次施用草甘膦(间隔30天)的结果表明,低剂量处理对抑制空心莲子草根组织莽草酸含量的积累更明显.     

龙葵和苘麻发生数量与大豆产量的关系

龙葵和苘麻发生数量与大豆产量的关系王义明（黑龙江省农科院植保所哈尔滨１５００８６）作物因杂草的危害而减产。但杂草发生数量不同，作物产量损失的程度也不同。龙葵（Ｓｏｌａｎｕｍｎｉｇｒｕｍ）植株繁茂多枝，菏麻（Ａｂｕｔｉｌｏｎｔｈｅｏｐｈｒａｓｉｔ）植株...     

玉米田两种阔叶杂草藜及苍耳对草甘膦的敏感性测定

苍耳Xanthium strumarium和藜Chenopodium album是常见的两种阔叶杂草,其在玉米田发生严重,影响了玉米的生长和产量.本文利用整株生物测定法对我国东北及黄淮海玉米产区采集到的苍耳及藜种群对草甘膦的敏感性进行了测定.种子室内培养至5～6叶期,喷施草甘膦后14 d称量鲜重,计算抑制杂草种群50％...     

广西灵川等4地刺苋和反枝苋对草甘膦的敏感性

刺苋和反枝苋在广西各地农田均有分布,综合运用培养皿种子检测法、整株生物测定法对广西4个不同地点的刺苋和反枝苋种群进行草甘膦敏感性测定。结果表明,桂林灵川的刺苋和桂林兴安的反枝苋对草甘膦表现出敏感性下降的情况。同时,使用生化指标测定法检测的植株体内莽草酸含量变化情况与其敏感性变化趋势基本一致。     

不同地区田旋花种群对草甘膦耐受水平的差异

在温室条件下,研究了草甘膦对北京、河北等地田旋花种群生长及其莽草酸含量变化的影响。结果表明,不同地区田旋花种群对草甘膦具有普遍的耐受能力,其中河北元氏的田旋花种群对草甘膦的耐受能力最强,GR50值为4 014.92 g a.i./hm2;北京海淀田旋花种群对草甘膦相对敏感,GR50值为957.65 g a.i./hm2。经922.5 ga.i./hm2草甘膦处理后,耐药性最高的河北元氏田旋花种群体内莽草酸含量累积缓慢,处理后14 d所受伤害能自行恢复并保持正常生长;敏感的北京海淀田旋花种群体内莽草酸迅速积累,在处理后7 d莽草酸含量达到最高值,植株生长受到一定程度的抑制。田旋花体内莽草酸含量与其耐药性高低呈负相关,因此可以通过检测田旋花经草甘膦处理后体内莽草酸的含量来明确不同地区田旋花对草甘膦耐受水平的高低。     

玉米田四种禾本科杂草对草甘膦的敏感性测定

马唐Digitaria sanguinalis、牛筋草Eleusine indica、狗尾草Setaria viridis和虎尾草Chloris virgata是我国北方和黄淮海玉米田4种主要禾本科杂草,是影响玉米产量和品质的主要因素之一。为了明确禾本科杂草对草甘膦的敏感水平,本研究采用整株生物测定法测定上述4种杂草种群对草甘膦的敏感基线,为将来我国种植转基因耐草甘膦玉米后,玉米田杂草防除提供数据支撑。结果表明,马唐55个种群GR₅₀值范围在13.36～550.28 g a.i./ha,均值为120.02 g a.i./ha。狗尾草69个种群GR₅₀值范围在7.22～201.96g a.i./ha,均值为50.45 g a.i./ha。牛筋草50个种群GR₅₀范围在25.19～808.54 g a.i./ha,均值为218.78 g a.i./ha。测定的所有马唐、狗尾草和牛筋草种群GR₅₀值均低于900 g a.i./ha(田间推荐中剂量),表明这三种杂草对草甘膦敏感。虎尾草34个种群GR     

三氯吡氧乙酸·草甘膦对免耕麦田杂草的防效及对田间光照和水肥的影响

为明确70%三氯吡氧乙酸.草甘膦可溶性粉剂在免耕小麦田的应用前景,建立小麦田杂草管理体系,研究了三氯吡氧乙酸.草甘膦对小麦田杂草的防除效果,并测定了田间透光率、杂草对养分和水分的吸收量和小麦产量。结果表明,三氯吡氧乙酸.草甘膦对免耕小麦田主要杂草菵草、小飞蓬、牛繁缕、野老鹳草等均有较好的防除效果。并显著提高了小麦田间的透光率,降低了杂草对田间养分和水分的吸收,促进了光合作用,小麦增产效果显著。     

Ecophysiological characteristics of four maize hybrids and Abutilon theophrasti

Combining empirical research with simulation modelling may improve our understanding of the dynamics of crop:weed competition and for testing hypotheses on the importance of specific traits for enhancing crop performance in mixtures. Two field experiments were conducted to quantify and compare estimates of traits important for radiation interception and utilization in four maize hybrids and Abutilon theophrasti grown in monoculture. Early leaf area growth rate did not vary among maize hybrids within a year, but varied among years. The response of CO₂ assimilation rate to absorbed radiation and leaf nitrogen content did not differ among hybrids. Abutilon theophrasti and two old maize hybrids partitioned more new biomass to stem relative to reproductive organs than newer hybrids. Old hybrids had greater specific leaf area during the period of most rapid growth, grew taller, and leaf area was distributed higher in their canopy. Extinction coefficients for diffuse radiation did not differ among hybrids or between years. Results suggest that these four maize hybrids may differ in their ability to intercept incident radiation, which may influence their ability to compete for light.     

侵染苘麻的菜豆金色黄花叶病毒的鉴定及基因组结构分析

为明确引起我国山西晋中地区苘麻叶片表现皱缩和花叶症状的病原物及其基因组分子特征, 本研究利用双生病毒简并引物扩增获得病毒基因组部分序列,经测序、比对后设计特异性引物扩增病毒基因组序列, 进而通过生物信息学方法构建系统发育树并进行序列分析。结果表明:引起苘麻叶片皱缩、花叶的病原物为番茄黄化曲叶病毒(tomato yellow leaf curl virus, TYLCV), 将该分离物命名为TYLCV-Abu, GenBank登录号为OP293347, 但未扩增到β卫星。该病毒DNA-A基因组全长为2 782 bp, 含有6个开放阅读框。TYLCV-Abu分离物与TYLCV茄子分离物KSQ1-3(GenBank登录号KC428753)的核苷酸序列一致性最高, 为98.99%, 其中C4和V2编码的蛋白变异较大。重组结果分析显示,分离物TYLCV-Abu是由TYLCV-F(GenBank登录号KY971326)和TYLCV-KSQ1-3重组得到, 重组区域为其基因组2 617－2 782 nt区域。这是首次从苘麻样品中扩增到TYLCV全基因组序列并进行分析。     

不同环境因素对苘麻种子萌发及出苗的影响

苘麻Abutilon theophrasti Medikus具有生长旺盛、结籽量大和适应性强等特点,已成为多种农田中的恶性杂草,研究环境条件对苘麻萌发的影响对进一步探究其生物学特性与综合防治技术具有重要意义。通过室内试验研究温度、光照、酸碱度、水分胁迫、盐胁迫与苘麻种子萌发及埋土深度与其出苗的关系。结果表明,在10～35℃下苘麻种子均可萌发,20～30℃为其最适萌发温度范围;种子萌发对光照不敏感;适应pH范围广,在pH 4～9条件下种子发芽率均在70%以上;水势在-0.2～0 MPa范围内种子发芽率最高,当水势小于-0.7 MPa时,种子萌发受到完全抑制;有较强的耐盐性,NaCl浓度为160 mmol/L时发芽率超过40%;种子对播种深度适应性较强,覆盖不超过8 cm的土层均可出苗。     

Model of crop:weed competition applied to maize:Abutilon theophrasti interactions. I. Model description and evaluation

A complex set of interactions among crops, weeds and their environment determines the impact of weed interference on crop productivity. These interactions can be simulated with dynamic crop:weed competition models, such as ALMANAC. In this study, ALMANAC was modified to simulate maize: Abutilon theophrasti competition. In the modified ALMANAC model, daily increases in leaf area index (LAI), height and rooting depth are attenuated on the basis of accumulated above-ground biomass and by environmental stress. Also, a simple, flexible method is adopted to partition radiation in a mixed canopy. A maize: A. theophrasti competition study conducted near Aurora, NY, in which a range of weed densities (0–16 plants m⁻²) were established in a maize crop, was used to evaluate the model. The modified ALMANAC proved to be a useful tool for segregating the maize response to competition in 1991 (simulated loss of 35% at the highest weed density) from those in 1992–94 (simulated losses not greater than 16%). Based on these findings, the modified ALMANAC model is judged to be capable of distinguishing between environmental conditions that facilitate large yield losses and those that allow maize to outcompete A. theophrasti .     

Comparative ecophysiology of grain sorghum and Abutilon theophrasti in monoculture and in mixture

Selection of crop genotypes that are more competitive with weeds for light interception may improve crop yield stability in the presence of weeds. The effects of interference on ecophysiological characteristics of Abutilon theophrasti Medic. and three morphologically diverse grain sorghum hybrids was evaluated to determine the relative tolerance and suppressive ability of the three hybrids and specific traits that may contribute to those differences. A tall hybrid was more tolerant to A. theophrasti interference than two medium stature hybrids. Early leaf area growth of two medium-stature sorghum hybrids was reduced by A. theophrasti interference, whereas early growth of a tall hybrid was unaffected. The height of A. theophrasti was greater than two moderate-stature hybrids but lower than the tall hybrid. Greatest leaf area density (L_D) of the tall sorghum hybrid was above that of A. theophrasti , whereas greatest L_D of medium-stature hybrids was below that of the weed. In monoculture, the partitioning of new biomass to various plant organs was similar among sorghum hybrids, whereas the tall sorghum hybrid partitioned less biomass to leaves and more to stems than medium hybrids in mixture. The results indicate that the three hybrids differ in their susceptibility to A. theophrasti competition. Crop traits that may contribute to greater crop competitiveness include greater maximum height and its growth rate and greater height of maximum leaf area distribution.     

银胶菊花对苘麻和稗的化感作用

通过室内培养皿法,研究了银胶菊花水浸提液及其乙酸乙酯相、正丁醇相、剩余水相不同极性组分对苘麻和稗种子萌发及幼苗生长的影响。定性测定结果表明,在50 g/L浓度处理下,水浸提液完全抑制苘麻和稗种子萌发,对苘麻和稗根长、芽长、鲜重抑制率分别为82.6%、89.1%、84.3%和91.7%、55.8%、39.1%;正丁醇相抑制苘麻种子萌发和幼苗生长最强,乙酸乙酯相抑制稗种子萌发和幼苗生长最强。定量测定结果表明,在1 g/L浓度处理下,乙酸乙酯相生物活性最高,苘麻和稗种子萌发率分别为13.3%和33.3%,对苘麻和稗根长、芽长、鲜重的抑制率分别为63.1%、80.0%、58.3%和51.3%、26.7%、23.3%。     

Over-winter predation of Abutilon theophrasti and Setaria faberi seeds in arable land

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.     

Predispersal seed predation of Amaranthus retroflexus and Chenopodium album growing in soyabean fields

Field experiments were made in 1998 and 1999 to determine the influence of tillage and soyabean (Glycine max) row width on predispersal weed seed predation in Amaranthus retroflexus L. (redroot pigweed) and Chenopodium album L. (common lambsquarters). Soyabean was planted in wide (76 cm) and narrow (19 cm) rows with conventional or conservation tillage. Additional control plots without soyabean were also established. The two objectives were to determine (1) whether predispersal seed predation occurs in A. retroflexus or C. album, and (2) whether disturbance (soil tillage) or microclimate (planting pattern) influence predation level. Mean rates of seed predation were 26% and 4% in A. retroflexus and C. album, respectively. Although these levels were low at the population level, individual plants of both species had predation levels ranging from 0% to 80%, however, very few individuals of C. album had levels of predation above 10%. Differences among tillage and row width treatments occurred for A. retroflexus, but not for C. album. Amaranthus retroflexus and C. album growing within the soyabean crop received less light than those in the no‐crop plots, and produced less above‐ground biomass, smaller terminal inflorescences, and fewer seeds per inflorescence. Plant height, terminal inflorescence weight, and total seeds were correlated with predation in both weed species.     

Model of crop:weed competition applied to maize:Abutilon theophrasti interactions. II. Assessing the impact of climate: implications for economic thresholds

The practical application of single-season economic thresholds for post-emergence weed control decisions has been frustrated by the impact of growing season, climate and edaphic factors on crop:weed interactions. Competition in a mixed plant community is a dynamic process that is contingent upon species-specific growth characteristics and their expression based on environmental conditions. To address these issues, a modified version of the ALMANAC competition model was parameterized and run to simulate maize: Abutilon theophrasti competition with 30 years (1966–95) of historical climate data for a site in New York State. Simulations indicate that, when weeds do not emerge before maize, maize will only suffer substantial yield reductions from A. theophrasti competition in two out of every 10 years at this site. It is also evident that economic thresholds based solely on the level of weed infestation are inherently flawed. Long-term simulation results suggest that estimates of early season water stress could be used as an independent tool for rationalizing post-emergence control decisions. Shifting the focus from quantifying the infestation intensity of the weed population to assessing the competitive status of the maize crop indirectly with climate information may alleviate many of the problems commonly associated with threshold management strategies.