Implementing sustainable weed control strategies is a major challenge in agriculture. Intercropping offers a potential solution to control weed pressure by reducing the resources available for weeds; however, available research on the relationship between crop diversity and weed pressure and its consequences for crop yield is not yet fully conclusive. In this study, we performed an extensive intercropping experiment using eight crop species and 40 different species mixtures to examine how crop diversity affects weed communities and how the subsequent changes in weeds influence crop yield. Mesocosm experiments were carried out under field conditions in Switzerland and in Spain, which differ drastically in terms of climate, soil and weed community, and included monocultures, two- and four-species mixtures, and a control treatment without crops. Weed communities were assessed in terms of biomass, species number and evenness, and community composition. Results indicate that intercropping reduces weed biomass and diversity in Spain but not in Switzerland. In Switzerland, despite the lack of a crop diversity effect on weeds, crop yield increased with crop species number. Moreover, in Switzerland, where soil resources were abundant, increasing crop yield correlated with reduced weed biomass. In Spain, where water and nutrients were limited, crop yield was not related to weed biomass or diversity. The presented research applies plant community ecology in the context of agricultural crop production systems. We demonstrate that, in our study, increased crop yield in mixtures was not due to increased weed suppression in diverse crop communities, and so must be the result of other ecological processes. We further show that crop–weed relationships vary across environmental conditions; more specifically, our study shows that weeds are less detrimental to crop yield in harsher environments compared to benign abiotic conditions, where alternative strategies are needed to control weed pressure and ensure the yield benefits provided by intercropping.

中文翻译：

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作物-杂草关系取决于环境，不能完全解释间作对产量的积极影响

实施可持续的杂草控制策略是农业的一项重大挑战。间作提供了一种通过减少可用于杂草的资源来控制杂草压力的潜在解决方案；然而，关于作物多样性与杂草压力及其对作物产量影响之间关系的现有研究尚未完全定论。在这项研究中，我们使用 8 种作物和 40 种不同的混合物进行了广泛的间作实验，以研究作物多样性如何影响杂草群落以及杂草的后续变化如何影响作物产量。Mesocosm 实验是在瑞士和西班牙的田间条件下进行的，这两种环境在气候、土壤和杂草群落方面存在巨大差异，包括单一栽培、两种和四种混合物以及没有作物的对照处理。杂草群落根据生物量、物种数量和均匀度以及群落组成进行评估。结果表明，间作减少了西班牙的杂草生物量和多样性，但在瑞士没有。在瑞士，尽管作物多样性对杂草没有影响，但作物产量随着作物种类的增加而增加。此外，在土壤资源丰富的瑞士，作物产量的增加与杂草生物量的减少相关。在水和养分有限的西班牙，作物产量与杂草生物量或多样性无关。所提出的研究在农作物生产系统的背景下应用植物群落生态学。我们证明，在我们的研究中，混合物中作物产量的增加并不是由于不同作物群落中杂草抑制的增加，所以一定是其他生态过程的结果。我们进一步表明，作物与杂草的关系因环境条件而异；更具体地说，我们的研究表明，与良性非生物条件相比，在更恶劣的环境中，杂草对作物产量的危害较小，需要替代策略来控制杂草压力并确保间作提供的产量收益。