灌溉水流对稻麦轮作田杂草种子传播的影响

Weed seed bank is the potential weed communities and is the real source of future weed populations in arable fields. The knowledge of weed seed bank dynamics (seed bank input and output) is benefit for the integrated weed control strategy. The input and output of seed bank were both influenced by the weed seed dispersal. In the middle and lower reaches of the Yangtze River valley, under the rice–wheat double cropping system, irrigation is regularly carried out and the irrigation water was determined as the important agent for seed dispersal. So it is of great importance for us to undersatand the seed dispersal by irrigation water flow in this region. Based on our previous discovery on seed dispersal by irrigation water, we propose the present proposal to continuously study of the seed adaption of dispersal by water and the characteristics of seed floating. Furthermore, the quantitative analysis of seed dispersal process by irrigation water and other dispersal agents was performed using a novel simple technique for tracking weed seeds in order that the mathematic model of seed dispersal dynamics would be obtained. Additionally, the bio-molecular technology was applied to analysis the origin of weed seed. As a result, the influences of seed dispersal by irrigation water on the spatial distribution of weed population and seed bank would be revealed. This will proved a theoretical basis and practices guidance for adoption of appropriate integrated measures to control the weed and reduce the herbicide application in arable land through the control of the water dispersal of weed seeds.

农田杂草种子库是潜在的杂草群落，是草害爆发的根源。掌握种子库输入、输出的动态变化规律对杂草的综合管理措施的实施具有重要的指导意义。杂草子实的传播影响种子库的输入和输出。在长江中下游地区流行稻麦连作种植制度下，灌溉是最普遍的一项农作过程，因此水流成为农田杂草的传播和扩散的主要媒介。本项目基于杂草子实水流传播这一现象，进一步研究其对水流传播的适应性，明确杂草子实的漂浮特性；并使用种子染色标记技术，研究杂草子实传播的漂流和非漂流因素，通过杂草子实随灌溉水流的传播动态的定量化分析研究，建立种子水流传播模型；并配合分子生物学技术，分析优势杂草间亲缘关系，明确杂草子实的来源。通过以上研究，揭示灌溉水流在杂草子实传播和空间分布的作用，以及对种子库的影响；为基于杂草种子传播规律的生态控草措施的选择和实施提供理论基础和实践指导，以最终控制田间杂草的发生和危害，减少化学除草剂的使用量，保护生态环境。

该项目针对长江中下游稻麦（油）连作田杂草对灌溉水的生态环境适应性特点开展了5个方面的研究，1）子实对水传播适应性研究；2）灌水对田间子实空间分布影响的研究；3）子实漂流动态研究；4）子实流动动态的示踪研究；5）抗性菵草种群的遗传分析。获得了杂草种子形态特征、大小和重量的数据，积累了杂草种子形态和重量与其漂浮能力关系的基础数据，直观地揭示了杂草种子适应漂浮的显微结构。首次应用藏红T染色染色示踪的新方法，利用Guass模型定量描述了菵草（Beckmannia syzigachne）种子随灌溉水流传播可达1.5km，在田间随风力积聚到田一角的漂浮动态，以及传播后的种子库分布。首次量化了杂草稻（Oryza sativa L）随收割机的跨田块传播与田块内的扩散，揭示了杂草稻残留量与传播面积、传播距离的关系以及旋耕对杂草稻种子库结构的影响。另外，研究了不同杂草管理措施对稻麦连作田杂草种子库和种群动态的影响；并在此基础上，成功试验应用拦网和网捞加快杂草种子库输出的生态技术措施，扩大了试验规模，建立以耗竭土壤潜杂草群落为技术核心的杂草可持续管理理论体系，同时为进一步推广该技术体系提供科学依据，期间已撰写及发表论文5篇，其中4篇SCI，3篇已在线发表，1篇已接收，1篇投稿已修回。发表国际学术会议论文1篇。授权专利1项，培养研究生3名。