【作者】 褚建君；

【导师】 李扬汉；

【作者基本信息】 南京农业大学 ， 植物学， 2000， 博士

【摘要】 本文以长江中下游地区稻茬油菜田和小麦田，近几年迅速发展起来的恶性杂草(?)草为研究对象，对之进行生物学、生态学和综合防治技术的研究。调查了(?)草的结实特性、种子的萌发特性及其在不同耕作条件下土壤中的分布，观察了其营养器官的解剖结构。为了揭示(?)草种群在油麦田杂草群落中数量增长的原因，运用数学模型的方法，对其种群动态、生态位、空间分布型、及其与其它杂草种群的种间联结关系进行了测定。还根据我国目前的生产实际，研究了田间(?)草生长对油菜和小麦的干扰作用，以及化学方法和生态方法控制(?)草的可行技术。结果如下： 1．(?)草的生长发育与油菜和小麦基本上保持同步节律性，但相对滞后。不同植株和同一植株穗的不同部位，种子的成熟度有较大的差异。成熟种子有4－5个月的休眠期，室温下土壤中浸水保存有利于其越夏、提高萌发率。深于2cm的土层中，种子不能出苗。连续免耕会使种子大量滞留在0－5cm的土表层，从而使(?)草的发生量加大。 2．(?)草的根茎叶均具高度发达的通气组织，可适应于多水环境。(?)草叶片的上表皮细胞在横切面上的排列呈平滑的“波浪形”，其表面积较小，可能不利于除草剂喷雾液的滞留与吸收。 3．田间(?)草的出草高峰期在油菜移栽后9周之内，而生物量的急剧增长则在3月中旬以后。在杂草群落中，(?)草的生态位宽度居第2位，说明其有潜在的较强的适应环境的能力；(?)草与雀舌草、看麦娘、牛繁缕、早熟禾、春蓼和稻搓菜等杂草种群的生态位重叠较大，与它们的生态要求比较接近。(?)草在田间的空间分布型为负二项分布，其聚集的原因主要是环境的影响，包括人为的翻耕、作物种植、施肥、除草等及其它自然因素的作用。 4．(?)草与早熟禾、牛繁缕和雀舌草等杂草种群表现为负联结关系，而与石龙内和通泉草等杂草种群则表现为正联结关系。在实行正常农事操作的稻茬油麦田中，与其它主要杂草种群相比，其自然竞争力弱，难以成为群落的优势种。但其具有“喜湿性”的特点，在冬季常常积水的休闲田中，发生量可大幅度上升。 5．由于简草生长的干扰作用，油菜的茎粗、株高、大分枝数和每株角果数等均呈下降趋势，但每角果粒数呈上升微弱的趋势，而千粒重则不受影响。油菜因商草生长而导致的产量损失，是直接通过每株角果数的大幅度下降而造成的。筒草生长对小麦的株高、每穗粒数、结实率和千粒重等，均无明显的影响，其对小麦产量造成的损失，是通过降低有效穗数来实现的。商草生长对油菜和小麦的竟争临界期均在作物种植后30天至80天左右。 6．在室内条件下，推荐剂量的高效盖草能、精禾草克、肢苯磺隆、膘马、异丙隆和飞达等除草剂，对 2叶 1心期踌草的防效均达 100％，这与生产实际不相附合。说明尚草对除草剂的敏感性易受各种因素的制约。在油菜田中，敌草强十胺苯磺隆对苟草的防效可达 85％以上；在小麦田中，骤马、异丙隆、异丙隆十绿黄隆和骤绿等处理，对同草的防效也在85％以上。檀物源助剂SD和SDP的应用，可使除草剂的效果有所提高。 7．稻草覆盖、轮作紫云英和稻草焚烧三种方法，均能有效控制商草的发生与危害。虽然、，稻底套种紫云英早期对苟草和其它杂草的控制作用不尽理想，稻草覆盖和稻草焚烧对后期简草和其它杂草的防效较低，但后两者对商草的有效控制发生在竞争临界期内，可以基本消除简草对作物的干扰作用；而紫云英最终对杂草种群数量的控制作用，也可降低土壤中杂草种子库的数量。 根据上述研究结果，本文提出了尚草的综合防治途径，还对杂草适应和农田杂草的可持续管理进行了探讨。更多还原

【Abstract】 This paper focus on biology, ecology and integrated management of American Sloughgrass (Beckmannia syzigachne (Steud.) Femald), a new malignant weed developed rapidly in rape and wheat fields following rice recently in the areas of the Changjiang River valley. Results obtained are as follows: The phenological spectrum of B. syzigachne was similar with rape and wheat, although the growth and development were a little later. Mature period of seeds varied among different individuals or different spike positions of the same plant. With 4-5 months long a rest period, mature seeds could keep themselves alive in summer best in soil with sufficient water. This weed could not emerge below 2cm depth in soil. Continues no-tillage would increase the seed number in soil 0-Scm deep, thus would lead to serious infection of this weed. With well-developed ventilating tissue in root, stem and leaf, B. syzigachne could grow well in water logged field. The above epidermal cells arrange in row with a smooth appearance of ave? thus would lower the area to absorb herbicides. Vast majority of B. syzigachne emerged before 9 weeks after crop planting, while fresh weight increased sharply after the middle of March. This weed population had a wider niche breadth, the second widest among 12 major weed populations in weed community, and had bigger niche overlap with Ste//aria a/sine, A/opecurus acquallis, Malachium aquaticum, Foa annua, Polygonum persicaria and Lapsana apogonoides. In rape, wheat or fallow, B. syzigachne was dispersed as negative binomial distribution, because of affections of environment including tillage, crop planting, fertilizer application, weed control, and other natural elements. Beckmannia syzigachne had negative association with Poa annua, Malachium aquaticum and Ste//aria a/sine, and had positive association with Ranunculus sceleratus and Mazus japonicus, etc.. Beckmannia syzigachne had poor adaptability and competition ability in rape or wheat field with no-herbicide application in histoiy, but would become dominant specie in water logged winter fallow, leading to yield loss of rape and wheat after a few years. Due to the growth of B. syzigachne, economic characters of rape such as stem diameter, plant height, branch number and pods per plant had a tendency to decrease, but seeds per pod increased slightly, while 1000-seed weight did not varied. Yield loss of rape was caused by the marked decline of pods per plant. Economic characters of wheat such as plant height, grains per spike, grain-set rate and 1000-grain weight were not affected apparently by weed growth. Yield loss of wheat was caused by the decline of effective spikes. The competition threshold of weed to no only rape but also wheat were 30 to 80 days after crop planting. In greenhouse, herbicides Dowco 453, Quinofop-ethyl, DPX-A788 1, isoproturon, fenoxaprop-p-ethyl, and glyphosate at the general dose could give 100% weed control over B. syzigachne, but in farm some above herbicides could only give lower weed control. Thus imply herbicide efficacy would be affected largely by various elements in environment. R(-)napropamide + DPX-A788 1 in rape field, fenoxaprop-p-ethyl, isoproturon, fenoxaprop-p-ethyl ?chlorsulfuron, isoproturon + chlorsulfuron could provided more than 85% weed control over B. syzigachne and other weeds. The application of natural synergist SD or SDP would provid more control compared with the same dose of the above herbicides.更多还原