燕山北部板栗林下杂草群落动态及生态位研究

为准确掌握燕山北部板栗园杂草的发生现状及群落组成,分别于2017年、2018年、2020年对燕山北部板栗林下杂草的种类、数量等进行调查,并运用Levins生态位指数和Pianka生态位重叠指数分析板栗林下优势杂草的生态位动态及群落对资源的利用情况和种间竞争情况。结果表明:(1)2017年、2018年、2020年燕山北部板栗林下杂草群落中分别有53种(27科48属)、47种(24科43属)和44种(24科41属)植物。其中优势杂草15种。(2)15种优势杂草中,葎草和灰绿藜占据较宽的生态位,它们对环境资源利用的多样性程度比较高。鸭跖草、艾蒿、狗尾草、茜草、苦荬菜、白屈菜、紫花地丁、灰绿藜、毛地黄和野大豆等物种对资源的利用能力在逐步增强。(3)杂草群落中生态位重叠值＜0.2的优势物种种对数明显减少,优势杂草物种在逐渐增加对周边资源环境充分利用的能力,灰绿藜逐渐取代葎草的优势地位,进而导致种间竞争关系更加复杂,群落向更高级更合理利用环境资源的群落方向演替,逐步形成更加复杂的种群结构。因此,准确掌握板栗园杂草的发生现状、优势种群及群落组成,可为燕山北部板栗林下杂草的针对性防治提供理论依据。     

耕作方式对新垦沙地农田杂草群落结构的影响

通过田间调查的方式,研究了黑河中游边缘绿洲新垦沙地农田杂草分布状况,并对不同耕作方式下农田杂草群落结构特征进行了分析。调查中共记录杂草16种,隶属10科。新垦沙地农田杂草群落基本组成为藜(Chenopodium album)+牛筋草(Eleusineindica)+狗尾草(Setaria viridis)+反枝苋(Amaranthus retroflexus)。与当地传统的地膜覆盖、秋耕和玉米连作耕作方式相比,秸秆覆盖、减少秋耕和玉米-大豆轮作均可增加农田杂草物种丰富度、多样性指数和群落优势度(P0.05)。与当地传统耕作方式相比,秸秆覆盖可增加杂草群落中牛筋草优势度比,降低藜和反枝苋优势度比;减少秋耕可增加狗尾草、反枝苋、灰绿藜(C.glaucum)和米瓦罐(Silene conoidea)优势度比,降低牛筋草优势度比;玉米-大豆轮作可增加米瓦罐优势度比。不同耕作方式对偶见种杂草在田间的分布和组成影响不明显。可以看出,新垦沙地农田杂草物种较少,群落组成单一;不同耕作方式对新垦沙地农田杂草物种多样性和群落结构组成有明显影响,进一步深入研究对沙地农田杂草合理防除具有重要的指导意义。     

规模化稻鸭生态种养对稻田杂草群落组成及物种多样性的影响

为探索规模稻鸭生态种养稻田杂草群落的变化动态,运用植物群落生态的方法研究了规模稻鸭生态种养、常规稻鸭生态种养和水稻单一种植稻田杂草的群落变化特点及控草效果。结果表明:规模稻鸭生态种养杂草密度显著降低,与水稻单一种植比较防效为94%;水稻分蘖到孕穗期稻田杂草主要由看麦娘(Alopecuruspratensis)、稗草(Echinochhloa crausgalli)、狗牙根(Cynodon dactylon)、水花生(Alternanthera philoxeroides)、鸭舌草(Mouochoria vaginalis)、水竹叶(Murdannia triquetra)和鳢肠(Eclipta prostrata)组成,抽穗期到成熟期主要由水花生、稗草、狗牙根和水竹叶组成。研究还表明,规模稻鸭生态种养水稻分蘖期物种丰富度、Simpon指数、Shannon-Wiener指数略高于水稻单一种植,Pielou指数低于水稻单一种植;孕穗期到成熟期物种丰富度、Simpon指数、Shannon-Wiener指数低于水稻单一种植,Pielou指数显著高于水稻单一种植。水稻全生育期规模稻鸭生态种养与常规稻鸭生态种养比较稻田杂草密度、杂草生物量和多样性指数差异不显著,但杂草生物多样性指数略有提高。说明规模稻鸭生态种养显著改变稻田杂草的群落结构和组成,可抑制杂草发生危害,达到有效控草目的。     

棉田蜘蛛群落时空生态位研究

对棉田7种主要蜘蛛的生态位进行了分析，从时间、水平空间、垂直空间一维生态位以及时空（水平和垂直）三维生态位进行宽度值和重叠值的定量估计。研究结果表明时间生态位宽度值为星的蛛（Pardosa astrigera，PAR）最大（0.9218），其次为芦苇卷叶蛛（Dictyna arundinacea，DIC）（0.9176），重叠值为三突花蛛（Misumenops tri-cuspidatus，MIS）和彭妮红螯株（Chiracanthiumm japonicum，CHI）最大（0.8083）。水平生态位宽度值除黄褐新圆蛛(Neoscona doenitzi，NEO)最小（0.4307）外，其余集中在0.8814-0.9912间，重叠值多数集中在0.7200-0.9500间。垂直生态位宽度值为草间小黑蛛（Erigondium gramincola，ERI）最大（0.7998），重叠值为草间小黑蛛和温室球腹蛛（Achaearanea tepidariorum，ACH）最大（0.7600）。三维生态位宽度值为草间小黑蛛（0.7189）最大，重叠值较大为草间小黑蛛和温室球腹蛛（0.3716）、彭妮红螯蛛和芦苇卷叶蛛（0.3715）、草间小黑蛛和彭妮红螯蛛（0.3695）。并据三维生态位重叠值对这7种蜘蛛进行竞争群的划分，得出明显的竞争群，包括草间小黑蛛、彭妮红螯蛛、温室球腹蛛、芦苇卷叶蛛4种蜘蛛。     

不同耕作、秸秆及氮素管理措施对冬小麦-夏玉米轮作田杂草生物量影响的研究

农田杂草的发生受多种生产措施的影响,是造成作物减产的重要原因之一。本研究目的在于探索我国华北平原冬小麦-夏玉米轮作体系下农田杂草对不同耕作、秸秆和氮管理的响应。研究结果发现:(1)夏玉米拔节期杂草种类和平均总生物量分别是冬小麦拔节期的1.25倍和6.66倍,因此,玉米季是轮作中农田杂草防治最主要季节,而马唐、打碗花、稗草等是杂草防治的主要对象。(2)不同管理措施对冬小麦季农田杂草生物量无显著影响。(3)夏玉米季,全免耕处理杂草平均生物量比半免耕处理高77.5%～99.4%。玉米拔节期,无小麦秸秆覆盖还田时,会促进翻耕杂草的发生。(4)夏玉米收获时,高氮水平(当季施氮量240 kg.hm-2)杂草平均生物量比低氮水平(当季施氮量120 kg.hm-2)显著低55.9%,耕作和氮效应的交互作用达显著水平,全免耕、低氮投入杂草生物量是半免耕、高氮投入的4.05倍,在翻耕条件下,高氮水平抑制杂草效果不显著。因此,华北平原区冬小麦-夏玉米轮作体系应加强夏玉米季杂草的综合防治,利用秸秆覆盖还田抑制杂草的发生,也可通过优化氮素管理改善作物生长发育从而抑制杂草发生,其中在全免耕条件下,可通过适当增加氮素供应水平而减轻杂草的危害。     

小麦田杂草种类及危害情况调查

调查掌握小麦田杂草种类、分布和危害程度,可为筛选高效除草药剂提供科学依据。对定西市不同区域的小麦田杂草发生情况开展了调查,结果表明,定西市共有麦田杂草15科38种,其中单子叶杂草6种,双子叶杂草32种。安定区、通渭县、陇西县、临洮县以及渭源县北部等干旱半干旱区分布较多的杂草有12种,渭源县南部以及漳县、岷县等二阴区分布较多的杂草有13种。有8个杂草优势种,其中苦苣菜、藜、狗尾草、灰绿藜、菊叶香藜等5种杂草危害较重,危害等级达到Ⅲ级;苦苣菜、藜、狗尾草为绝对优势种,危害最重。杂草优势种是防除的重点对象,建议结合杂草特性,筛选高效除草剂加以科学防除。     

乌冈栎群落乔木层种群生态位分析

 通过野外群落调查,以物种重要值为生态位计算的资源状态指标,应用Levins公式、Hurtlbert公式、Pianka公式和Schoener公式,对福建将石、浙江开化、广东仁化、湖南沅陵和贵州荔波的乌冈栎群落乔木树种的生态位宽度、生态位重叠和生态位相似性比例进行了计算与分析。结果表明:1)乌冈栎作为群落的建群种,其生态位宽度要大于其他物种,Levins和Hurtlbert生态位宽度值在各群落中分别为0.678、0.690、0.693、0.682、0.694和0.879、0.950、0.967、0.908、0.972。2)从Pianka生态位重叠值来看,Np0.4的高相似性分布段中,将石、开化、仁化、沅陵和荔波所占比例分别为44.76%、24.09%、33.33%、39.08%和43.69%,相似性比例越高的种对,对资源的需求就具有越高的趋同性,由此可判断群落生态位分化的程度。4)乌冈栎林属于稳定的地形顶级群落,各物种所占据的生态位是自然界长期选择的结果,群落处于动态的稳定状态;在没有外部干扰的情况下,乌冈栎将长期保持优势种的地位。     

黄河三角洲植被演替过程种群生态位变化研究

对黄河三角洲天然湿地陆生植被和水生植被两种演替序列的种群生态位宽度和生态位重叠进行了调查研究。结果表明: 陆生植被经过翅碱蓬群落、碱蓬柽柳群落、柽柳群落、白茅群落的演替过程, 每个阶段优势种的生态位宽度都较大。翅碱蓬群落阶段优势种翅碱蓬的生态位宽度达9.99, 碱蓬柽柳群落阶段碱蓬的生态位宽度为9.72, 柽柳群落阶段柽柳的生态位宽度为9.20, 白茅群落阶段白茅的生态位宽度为9.31。水生植被的演替序列为眼子菜金鱼藻群落(沉水植物)阶段、浮萍水鳖群落(浮水植物)阶段、芦苇水烛群落(挺水植物)阶段和杞柳芦苇群落(湿生植物)阶段, 沉水植物阶段优势种眼子菜的生态位宽度为8.62, 浮水植物阶段优势种浮萍生态位宽度为9.23, 挺水植物阶段优势种芦苇的生态位宽度为8.59, 湿生植物阶段优势种杞柳生态位宽度为7.45。生态位宽度计测结果较好地对应着各种群在群落中的地位和作用, 生态位宽度在演替系列中的动态也较好地反映了种群在群落演替过程的数量动态。各演替阶段生态位重叠计算结果表明, 各阶段种群间的生态位重叠值低, 每一阶段内种群间有较高的生态位重叠     

土壤杂草种子库与杂草综合管理

土壤杂草种子库是农田杂草发生危害的主要根源,种子库的动态变化规律对于杂草的综合管理具有非常重要的意义。目前研究表明,杂草种子库的密度和组成变化很大,与田间杂草群落具有密切的联系。杂草种子库时刻处于输入和输出的动态变化之中。耕作方式影响杂草种子在土壤中的垂直分布,从而间接影响种子库的密度和种类组成;作物轮作使杂草的生存环境趋于多样化,能够限制某些对单一种植系统有着良好适应性的杂草种类的生长,作物轮作对杂草种子库种类组成和丰富度的影响要大于耕作方式;杂草管理措施能够大大降低田间杂草的结实,从而减小杂草种子库的规模。随着人们对除草剂使用和环境安全问题的日益关注,发展基于生态规律的杂草管理措施越来越受到人们重视,结合近几年国内外的研究进展,作者提出了杂草种子库今后的一些新的研究发展方向。     

两种生态控草措施对丘陵茶园杂草群落及物种多样性的影响

实现丘陵茶园杂草生态控制, 可有效减少茶园土壤水分和养分的消耗, 减少或避免使用化学除草剂.本研究根据生态位先估和生态位竞争原理, 设计覆盖稻草和间种豆科绿肥白三叶草(Trifolium repens)两种杂草生态控制技术, 同时设置清耕对照(CK), 采用小样方多点取样连续两年调查茶园杂草种群数量、生物量、平均株高等指标, 发现茶园共有杂草16科31属31种; 3个处理春季(4月)发生的杂草特征表现为生长速度较慢、生物量小、株高在30 cm以下; 夏季(7月)和秋季(9月)对照的优势恶性杂草多度(Pi)高达0.788和0.759, 稻草覆盖处理分别为0.256和0.420, 间种白三叶草处理恶性杂草种类较少发生(Pi值均低于0.050); 稻草覆盖处理茶园春、夏和秋季杂草物种丰富度(S)、种群多样性(H)、均匀度(J)等指数均高于对照, 优势集中性指数(C)低于对照; 间种白三叶草处理春、夏和秋季杂草总数量和生物量均显著低于对照, 夏、秋季杂草平均株高显著低于对照.结果表明两种生态控草处理措施能改变茶园杂草群落结构, 有效控制杂草的生长.     

长期定位施肥小麦田间杂草生物多样性的变化研究

长期定位试验研究不同施肥小麦苗期田间杂草生物多样性的变化结果表明,不同施肥处理田间杂草种类与各杂草相对丰度均发生变化,且各处理间Shannon多样性指数(H′)、Shannon均匀度指数(E)和Margalef物种丰富度指数(DMG)均存在差异,其原因可能是由于不同施肥造成各处理间土壤养分的不同,各种杂草的生长因而受其不同影响所致。     

基于剪切波变换和无人机麦田图像的区域杂草识别方法

区域杂草的识别有利于植保作业中的除草剂精准喷施。现有图像处理技术主要针对行间和株间杂草,而传统的图像采集与分析设备对苗期麦田杂草的识别存在一定局限性,难以满足非人工的区域性喷洒农药等作业需求。由于麦田区域中的麦苗和杂草具有形态和颜色区分度差的特点,传统的图像识别方法难以有效识别。针对此问题,该文提出利用剪切波变换对无人机麦田区域图像中杂草进行识别。该方法利用其自身的方向敏感性以及在纹理识别中的方向无关性,根据麦田区域图像在杂草较多的部分叶片纹理杂乱,反之则纹理相对规则的特点,处理得到不同尺度和不同方向下小麦与杂草的剪切波系数。然后针对小麦和杂草剪切波系数的不同特征,对剪切波系数矩阵进行归一化处理,同时对其均值和方差进行了统计分析,得到麦苗和杂草剪切波系数图中竖直锥第二尺度所有系数均值的区分值约为0.07,第二尺度各个方向的均方差均值的区分值约为0.08。通过对含杂草麦苗区域图像以及麦苗区域图像的验证,准确率为69.2%,效果优于传统的灰度共生矩阵方法。此外,该文对无人机拍摄区域图采用分块的方法,实现了对非麦苗区域的有效标识。由此可见,剪切波变换方法能够为基于低空植保无人机喷洒农药中的区域杂草识别提供参考。     

Einfluss von Bodeneigenschaften auf die Segetalflora von Ackerflächen

Impact of soil properties on weed distribution within agricultural fields Occurrence and distribution of weeds on agricultural fields are often heterogenous. The influence of various soil properties on the spatial structure and density of weed populations was investigated on two agricultural fields with special regard to three weed species (Polygonum amphibium, Cirsium arvense, Veronica hederifolia). Based on field specific sampling grids, weed counting and soil sampling were done. For all grid points, soil analysis was carried out (texture, organic C, total N, pH, soil nutrients P, K, Mg). Soil texture, soil organic C, and soil nutrients are the factors with the highest influence on the occurrence of the species studied.     

Differential allelopathic potential of sunflower (Helianthus annuus L.) genotypes on weeds and wheat (Triticum aestivum L.) crop

Studies were conducted to screen eight sunflower (Helianthus annuus L.) genotypes for their allelopathic potential against weeds and wheat crop, which customarily follows sunflower in Iraq. All sunflower genotypes significantly inhibited the total number and biomass of companion weeds and the magnitude of inhibition was genotype dependent. Among the eight genotypes tested, Sin-Altheeb and Coupon were the most weed-suppressing cultivars, and Euroflor and Shumoos were the least. A subsequent field experiment indicated that sunflower residues incorporated into the field soil significantly inhibited the total number and biomass of weeds growing in the wheat field. Sunflower genotypes Sin-Altheeb and Coupon appeared to inhibit total weed number and biomass more and significantly increased wheat yield compared with the least-suppressive genotypes (Euroflor and Shumoos). Chromatographic analyses by HPLC revealed the presence of 13 secondary metabolites in residues of the tested sunflower genotypes. All the isolated compounds appeared to be phenolic, with the exception of terpinol, which is a terpenoid derivative. The total concentration of Phytotoxins (phenolic compounds) was found to be higher in the most-suppressive potential genotypes compared with the least-suppressive genotypes.     

Glyphosate hormesis in broad-leaved weeds: a challenge for weed management

Little is known of glyphosate-induced hormesis in weeds and how this might influence weed management. To test the hormetic effect of low doses of glyphosate on broad-leaved weeds, two experiments were conducted, in the laboratory and the screenhouse. The hormetic effects of glyphosate solution in growth media (0, 65, 130, 250, and 500 g acid equivalent (a.e) ha^?1) and foliar spray (0, 4, 8, 16, 32, and 64 g a.e. ha^?1) were tested on four broad-leaved weeds (Coronopus didymus, Chenopodium album, Rumex dentatus, and Lathyrus aphaca). Glyphosate solution in the range 65–250 g a.e. ha^?1 stimulated the germination and seedling growth of all tested weeds. However, at 500 g a.e. ha^?1 inhibition of germination and growth was observed. Foliarly applied glyphosate in the range 4–32 g a.e. ha^?1 increased root and shoot length, dry biomass, and seed production ability of all four weeds species; however, the stimulatory response was species dependent. These results indicate that glyphosate hormesis could play a significant role in altering crop/weed competition and might influence weed management.     

Soil and weed management for enhancing arbuscular mycorrhiza colonization of wheat

Tillage and weed control are critical components of cropping systems that need to be combined such that crops benefit from reduced competition. However, weeds may also contribute to the biological diversity within the agro‐environment. This greenhouse study investigated whether common weeds of arable cropping systems were suitable host plants for arbuscular mycorrhizal fungi (AMF), allowing the development of extraradical mycelium (ERM) that can contribute to the early colonization of a following wheat crop, especially in the absence of soil disturbance. Weeds were allowed to grow for up to 2 months before being controlled by soil disturbance or herbicide application (glyphosate or paraquat). Pregerminated wheat seeds were then planted. Chemical control of the weeds prior to sowing enhanced the early arbuscular mycorrhiza (AM) colonization rate of wheat roots, whereas mechanical disturbance was less acceptable as a method of weed control for rapid AM colonization. The type of herbicide (contact or systemic) had no impact on colonization of the wheat crop. Enhanced AM colonization promoted early P acquisition and growth of the crop. Appropriate management of weeds emerging between two consecutive cropping seasons coupled with no‐till soil management could ensure a quick and efficient AM colonization of the following wheat plants.     

Cardinal temperatures for seed germination of wild barley,barley grass and hoary cress

It is necessary to understand the effects of environmental conditions, especially temperature, on weed seed germination patterns, in order to make comprehensive and effective weed management decisions. The effect of cardinal temperature (0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C and 40°C) on the germination pattern of three noxious weeds, such as wild barley (Hordeum spontaneum Koch.), barley grass (H. murinum L.) and hoary cress (Cardaria draba L.) in wheat fields of Iran, was studied in three separate experiments. The experiments were conducted based on completely randomized design (CRD) with four replications. The result showed that the germination of all three species started at low temperatures and there was no significant difference in germination percentage (GP) at lower temperatures. About 50% of the weed population germinated within a short period when using a dent-like model indicating the high ability of these weeds to compete for space and resources. Segmented and dent-like models were used to evaluate the cardinal temperatures. The results showed that dent-like model was the preferred model to evaluate germination rate in relation to variable temperatures in hoary cress, while the segmented model was better in wild barley. However, there was no significant difference between the two models for barley grass. The results of this study showed that mechanical, cultural (pre-planting irrigation) and chemical practices could be more useful and effective at 10–30°C.     

丙酯草醚对百合生长的影响及其在鳞茎中的残留

百合田间种植易受杂草危害,为寻求高效低毒、适用于百合生产的新型除草剂及其使用技术,本试验研究了我国创制的新型高效除草剂丙酯草醚对百合田间杂草的控制情况和对其生长的影响规律,同时利用高效液相色谱法检测了其在百合鳞茎中的残留。结果表明,丙酯草醚作为土壤处理剂,于杂草芽前处理,在60 g ai·hm~(-2)用药剂量下能有效防除百合田间禾本科和部分阔叶杂草,杂草鲜重总防效为87.2%;百合田早期喷施丙酯草醚,不仅对百合整个生育期的植株无药害,而且处理组百合在现蕾期、始花期和盛花期的株高、地上部鲜重、花蕾数、花苞数和花朵数均极显著大于对照组,丙酯草醚处理显著促进了百合的生理和生殖生长。高效液相色谱分析结果表明,百合田早期喷施丙酯草醚,在处理组百合鳞茎中未检出丙酯草醚残留(检测限0.001 mg·kg~(-1)FW)。由此可见,丙酯草醚能用于百合田间杂草防除,对百合生长及其食用是安全的。本研究结果为百合田间杂草防除提供了科学依据和技术支持。     

Effect of soil tillage and weed control methods on weed biomass and yield of lentil (Lens culinaris Medic.)

Abstract

The study was carried out in dryfarming areas in Ankara, Turkey, over 2 years (2001 – 2002 and 2002 – 2003). The objective was to determine different soil tillage and weed control methods on weed biomass and yield components, yield of lentil (Lens culinaris). This study compared the effects of two tillage systems (shallow minimum tillage and traditional tillage) and three weed control methods (weedy check, hand weeding and herbicide) on weed biomass, growth characteristics, seed yield and some yield components of lentil. Significant differences were found among weed control methods for weed biomass and yield parameters of lentil. Tillage systems had no significant effect on weed biomass or yield of lentil. The highest yield and lowest weed biomass was found in the hand-weeded treatment compared to the other weed control methods. Results of this research indicate that weeds are a main constraint for lentil growing under dryland conditions. Grain yield of lentil was reduced more than 60% due to uncontrolled weeds.