【作者】 韦继光；

【导师】 强胜；

【作者基本信息】 南京农业大学 ， 植物学， 2005， 硕士

【摘要】 农田杂草群落综合体是由土壤潜杂草群落（种子库）和地上显杂草群落（杂草植被）共同组成，其中潜杂草群落是决定将来田间杂草发生危害的根本性因素，研究和控制土壤潜杂草群落，对于杂草综合管理具有十分重要的意义。本文利用水洗法研究了中国农田潜杂草群落的结构特征，并结合环境条件对潜杂草群落区系进行了分析研究；对不同淹水强度下四种类型农田潜杂草群落的出苗动态进行了研究，探讨以水治草的机理；比较研究了主要农田杂草种子在不同埋藏环境下种子活力动态；进一步研究了稻麦轮作田杂草管理措施对潜杂草群落动态的影响。详细结果如下：中国农田土壤杂草种子库密度在333.3～2152000粒·m^-2之间（0～15cm耕层内），平均密度高达102851.7粒·m^-2，通过水洗计数的方法共统计到35个科139种杂草，种类最多的为禾本科，有21种，其次为菊科18种，莎草科15种，玄参科8种。旱作物田中出现84种，水连作、水旱轮作田种子库中发现100种，在三种类型作物田中均出现的杂草有44种。各样点杂草种子库密度地区变化很大，优势种类也存在明显的地域性差异。从南到北，海南岛农田中有尖瓣花（Sphenoclea zeylanica）、簇花粟米草（Mollugo oppositifolia）、龙爪茅（Dactyloctnium aegyptiacum）、伞房花耳草（Hedyotis corymbosa）等典型的热带杂草，广西农田有胜红蓟（Ageratum conyzoides）、咸虾花（Vernonia patula）、草龙（Jussiaea linifolia）等典型南亚热带杂草，华中有裸柱菊（Soliva anthemifolia）、千金子（Leptochloa chinensis）、看麦娘（Alopecurus aequalis）、牛繁缕（Malachium aquaticum）等典型亚热带杂草，华北农田有播娘蒿（Descurainia sophia）等典型暖温带杂草，东北有藜（Chenopodium album）、止血马唐（Digitaria ischaemum）、稗（Echinochloa crusgalli）等温带杂草，内陆高原农田有棒头草（Polypogon fugax）、密花香薷（Elsholtzia densa）、鼬瓣花（Galeopsis bifida）、头状蓼（Polygonum nepalense）等高寒气候带杂草。异型莎草（Cyperus difformis）、通泉草（Mazus japonicus）、碎米莎草（Cyperus iria）、马唐（Digitaria sanguinalis）、狗尾草（Setaria viridis）、牛筋草（Eleusine indica）、荠菜（Capsella bursa-pastoris）等为全国分布的杂草。为明确不同淹水强度对农田杂草种子出苗动态的影响，比较研究了南方旱地、南方水旱轮作田、北方旱地、北方水旱轮作田四种类型农田潜杂草群落在淹水作用下发生数量的变化动态，结果表明淹水可以大幅度降低旱作物田杂草的萌发出苗，并在一定程度上抑制了水旱轮作田夏熟杂草的发生危害，同时在一定程度上提高水旱轮作田水田杂草的出苗率。将24种主要农田杂草种子埋藏于自然旱地、湿润土层、淹水土层三种土壤环境下，调查研究其种子活力随埋藏时间的动态变化，结果表明，各埋藏处理对各类型杂草种子活力的降低作用大小为淹水土层＞湿润土层＞自然旱地，并且土壤水分含量的增大对旱作物田杂草种子活力的影响大于对水田杂草种子活力的影响。进一步研究了人工除草（MW）、化学除草（CW）、无草截流（WF1）、无草不截流（WF0）及对照截流（CK）等5种控草措施持续作用下土壤种子库密度和物种组成的动态变化。发现在5种杂草管理措施作用下，种子库中的物种组成发生了较大变化，种子库的Shannon-Wiener指数、Pielou群落均匀度随控草措施地连年进行而有不同程度降低，Simpson优势度指数逐年升高。杂草种子库密度在各种杂草管理措施作用下呈逐年降低的趋势，种子库耗竭效果WF1＞WF0＞CW＞MW＞CK。种子库中杂草相对优势度在不同控草措施作用下发生了较大变化，种子库组成差异逐年增加。田间发生的杂草种群的种类和数量也有较大变化。进一步研究了稻鸭共作复合生态控草体系下田间杂草群落特征及杂草种子库动态变化规律，结果表明稻鸭共作显著降低了0～5cm和5～10cm土层的杂草种子比例，使杂草种子在土壤中的垂直分布趋于均匀。随着稻鸭共作的连年进行，杂草种子库的多样性及均匀度不断降低，优势度逐年上升。在一定年限内，稻鸭共作使杂草种子库规模不断缩小，其中对稻田杂草种子的影响大于麦田杂草，使稻田主要杂草的种子密度迅速降低。在稻鸭共作控草体系连年作用下，种子库优势种组成由原来的陌上菜（Lindernia procumbens）+通泉草+碎米荠（Cardamine hirsute）逐渐演变为通泉草+看麦娘+陌上菜+节节菜（Rotala indica），种子库组成与稻鸭共作前的相似性在一定年限内逐年降低，表明稻鸭共作在一定程度上改变了杂草种子库的物种组成，使潜杂草群落发生了演替；在稻鸭共作条件下，田间杂草密度逐年降低，下降趋势符合阻滞模型y=k+a·e^bx，模型参数b反映了杂草种群的下降速率。稻鸭共作群落相似性与稻鸭共作初期相比逐年降低而后有所回升，表明田间杂草的群落结构不断发生适应演替。随着稻鸭共作的连年进行，系统的控草效果逐渐上升而后下降，总体控草效果在84％以上。稻鸭共作总体上是一种非常有效的生态控草措施，具有显著的经济和社会效益。更多还原

【Abstract】 The "potential" weed community-soil weed seed bank and the "real" weed community-above ground weed vegetation formed the weed community complex in farmland, and the potential weed community was the primary source of future weed occurrence and infestations. The study and control of potential weed community play an important role in integrated weed management system （IWM）. Elutriation of sampled soil and account of weed seeds were used to study characteristics of the potential weed communities in farmland in China, and the flora of potential weed communities was studied by associating with environmental conditions. The dynamics of germination ratio of four types of weed seed bank in farmland under different submerged intensions were studied to reveal the mechanism of controlling weeds by water management. Effects of days for the burying lasted on the dynamics of main weed seed viability under different burying environments were evaluated. Further studies were conducted to evaluate the effects of different weed management strategies on the dynamics of the potential weed community under rice-wheat cropping system. The detailed results are as followings.Fields in China had a weed seed bank with a density of ranging from 333.3 seeds·m^-2 to 2152000seeds·m^-2 （0¹5cm soil layer） , in which average weed seed density was 102851.7 seeds·m^-2. A total of 139 weed species belonging to 35 families was recorded in the soil seed bank. The dominant weed family was Gramineae, which had 21 weed species, the second was Compositae family, 18 weed species, the third was Cyperaceae family, 15 weed species, and the fourth was Scrophulariaceae, 8 weed species. Among them, 84 weeds were found in seed bank of dry-cropping fields, 100 in continuous wet cropping and wet-dry cropping rotation fields and 44 all in the three types of cropping system. There were the marked differences of seed bank density and dominant weed species in different fields. From south to north, Sphenoclea zeylanica, Mollugo oppositifolia, Dactyloctnium aegyptiacum, Hedyotis corymbosa were mainly found in fields in Hainan; Ageratum conyzoides, Vemonia patula, Jussiaea linifolia in Guangxi; Soliva anthemifolia, Leptochloa chinensis, Alopecurus aequalis, Malachium aquaticum in central China; Descurainia sophia was only found in northem China; Chenopodium album, Digitaria ischaemum, Echinochloa crusgalli in north-east China; Polypogon fugax, Elsholtzia densa, Galeopsis bifida, Polygonum nepalense in plateau of inland. Cyperus difformis, Mazus japonicus, Cyperus iria Digitana sanguinalis, Setaria viridis, Eleusine indica and Capsella bursa-pastons were found in most regions in China.The effects of different submerged intension on the dynamics of germination ratio of weed seed bank in four different cropping systems, southern dry land, southern wet-dry cropping, northern dry land, northern wet-dry cropping, were compared. The results showed that the germination of weed seed in dry cropping field under submerging reduced remarkably. Winter weed seed in wet-dry cropping rotation field was controlled to a certain extent. The germination ratio of paddy weed seed in wet-dry cropping system was increased.Seeds of 24 main weed species in farmland were buried in the soil under three different conditions, natural dry land, moisture soil layer, submerged soil layer, to study the dynamics of seeds viability. The results showed that the sequence for the effects of different burying treatment on the decline of seed viability was submerged soil layer＞moisture soil layer＞natural dry land. Influence of increasing of soil moisture content on seed viability of weed seed in dry cropping system was higher than that of paddy weeds.Effects of five different weed management measures, manual weeding （MW）, chemical weeding （CW）, weed flee （WF1）, weed free without water interception （WF0） and a check with water interception （CK）, on the dynamics of weed seed bank under rice-wheat cropping system were further evaluated. The results showed that under different weed management measures, Pielou evenness indices of weed seed bank and Shannon-wiener indices decreased and Simpson’s dominance indices increased steadily when soil seed bank managed by the above five weed management measures. The density of weed seed bank declined annually, and the sequence for the effects of seed depletion was WF1＞WF0＞CW＞MW＞CK. There were obvious changes in relative abundance of weed species among the potential weed communities under different control measures. The differences between community similarity indices within management measures increased with the year. The density and species composition of above ground weed communities also showed marked changes.Further study on the effects of rice-duck farming on the dynamics of soil weed seed bank showed that the seed proportion of 0～5 cm and 5～10 cm soil depth were reduced significantly, and weed seeds tended to distribute more evenly among soil layers. With the implementation of rice-duck farming continued on, evenness and species diversity of weed seed bank decreased annually, but species dominance increased steadily. The size of weed seed bank declined annually under rice-duck farming system in a certain range of years. Influence of rice-duck farming on seeds of paddy weeds was more remarkable than wheat weeds, and the density of major weed species in paddy fields reduced rapidly. Under continuous rice-duck farming system, dominant species of weed seed bank changed from Lindernia procumbens+Mazus japonicus+Cardamine hirsute to Mazus japonicus+ Alopecurus aequalis+Lindernia procumbens+Rotala indica, Similarities of weed seed bank between rice-duck farming and pre rice-duck farming declined annually within a certain range of years, which indicated that rice-duck farming could change the species composition of weed seed bank and cause the potential weed community to shift. Continuous five-year weed survey under rice-duck farming system showed that the density of paddy weeds decreased annually and the reduction trend was best fitted by the damping model y= k+a·e^bx, in which the parameter b could reflect the rate of declination of weed populations. The similarity index of weed communities in paddy fields decreased consecutively compared with the initiation of rice-duck farming, but increased again in the fifth year, which indicated that the structure of weed community in paddy fields was not steady. With the implementation of rice-duck farming system continued on, the weed control effects steadily enhanced in paddy fields, decreased in the fifth year and the overall effect were above 84％after five years. Rice-duck farming is an effective ecologically based weed management strategy and has significantly economic and social benefits.更多还原