1. Beckmannia syzigachne had negative association with Poa annua, Malachium aquaticum and Stellaria alsine, and had positive association with Ranunculus sceleratus and Mazus japonicus, etc. 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。