Weed seeds are introduced to agronomic systems naturally or through human‐mediated seed dispersal, and introduced seeds have a high chance of being resistant to selective, in‐crop herbicides. However, colonisation (invasion) rates for a weed species are usually much lower than rates of seed dispersal. The current research investigated colonisation of a winter annual wheat cropping system in Western Australia by a range of winter or summer annual weed species. The weed seeds were sown (at 100 seeds/m²) directly before seeding the crop in 2016 and allowed to grow in the following 3 years of wheat. Selective herbicides were not applied, to simulate growth of weed populations if the initial seed had been resistant to herbicide. Bromus diandrus, Hordeum leporinum, Rumex hypogaeus, Sonchus oleraceus, Polygonum aviculare, Lolium rigidum, Citrullus amarus and Tribulus terrestris colonised the crop, while Dactyloctenium radulans, Chloris truncata and Salsola australis failed to establish over 3 years. The most successful weed was B. diandrus, with a plant density of 1,170/m² by the third year and seed production of 67,740/m². The high density of B. diandrus reduced wheat density by 76% in the third year and reduced average yield by 36%. Lolium rigidum reduced average yield by 11%, and the other weed species did not affect crop yield. Further research is required on the invasiveness of these species in other regions, but it is clear that the spread of B. diandrus to new areas or the introduction of resistant B. diandrus seeds via contaminated grain should be avoided.

中文翻译：

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西澳大利亚州小麦农艺杂草的入侵性

杂草种子可以自然地或通过人类介导的种子传播引入农艺系统，并且引入的种子极有可能对选择性作物内除草剂具有抗性。但是，杂草物种的定居（入侵）率通常比种子散布率低得多。目前的研究调查了西澳大利亚州冬季一年生小麦种植系统在一定范围内的冬季或夏季一年生杂草物种定植情况。在2016年播种之前，直接播种杂草种子（以100种子/ m ^2的速度播种），并在接下来的3年小麦中生长。如果初始种子对除草剂具有抗性，则不使用选择性除草剂来模拟杂草种群的生长。双雄雀麦，大麦leporinum，Rumex hypogaeus，Sonchus oleraceus，何首乌，硬质黑麦草，Citrullus amarus和Terbulus terrestris定居了该作物，而Dactyloctenium radulans，Chloris truncata和Salsola australis则在三年内未能建立。最成功的杂草是B. diandrus，到第三年的植物密度为1,170 / m ²，种子产量为67,740 / m ²。高密度的B. diandrus在第三年使小麦密度降低了76％，平均单产降低了36％。硬叶黑麦草降低了11％的平均产量，其他杂草种类并未影响农作物的产量。需要对这些物种在其他地区的入侵性进行进一步研究，但很明显，应避免将双歧双歧杆菌传播到新地区或通过污染的谷物引入抗双歧双歧杆菌种子。