Cereal varieties are commonly tested in the presence of weeds in organic agriculture, and a variety of test programmes with weeds are relevant in relation to fields containing herbicide-resistant weeds. However, the interpretation of results from variety trials with weeds is complex because different levels of weed pressure affect the yield differently. Crop yield is a result of the combined effect of weed suppression, crop tolerance and the weed-free yield. Until now, there has been no attempt to separate weed suppression, crop tolerance and weed-free yield in ordinary variety trials without weed-free plots. This study applied a new approach based on the combination of functional trait analysis and analysis of variance (ANOVA). A total of 16 variety trials were analysed with early crop coverage, final canopy height and disease severity as functional traits. The main objectives were to quantify weed suppression, crop tolerance and weed-free yield in spring barley varieties, and to evaluate the importance of the trade-off between weed suppression and weed-free yield. Results showed that early crop coverage and final canopy height both increased weed suppression, and taller cultivars tolerated weeds better than shorter cultivars. However, a trade-off between canopy height and weed-free yield made it difficult to justify the selection of tall varieties unless the weed pressure was at its maximum level in the trials. Large early crop coverage was an advantage in terms of weed suppression and weed-free yield, making early coverage a better selection criterion than final canopy height under the condition that early coverage is a result of genotypic variation. Future studies have to show how well genotypic and phenotypic variations are related in terms of early coverage and final canopy height.

中文翻译：

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在没有无杂草地块的谷物品种试验中量化杂草抑制、作物耐受性和无杂草产量的新方法

谷物品种通常在有机农业中存在杂草的情况下进行测试，并且各种杂草测试程序都与含有抗除草剂杂草的田地相关。然而，对杂草品种试验结果的解释很复杂，因为不同水平的杂草压力对产量的影响不同。作物产量是杂草抑制、作物耐受性和无杂草产量综合作用的结果。到目前为止，还没有尝试在没有无杂草地块的普通品种试验中区分杂草抑制、作物耐受性和无杂草产量。本研究应用了一种基于功能性状分析和方差分析 (ANOVA) 相结合的新方法。对 16 个品种试验进行了早期作物覆盖分析，最终冠层高度和疾病严重程度作为功能特征。主要目标是量化春季大麦品种的杂草抑制、作物耐受性和无杂草产量，并评估杂草抑制和无杂草产量之间权衡的重要性。结果表明，早期作物覆盖率和最终冠层高度都增加了杂草抑制，并且较高的品种比较短的品种对杂草的耐受性更好。然而，除非杂草压力在试验中处于最大水平，否则树冠高度和无杂草产量之间的权衡使得很难证明选择高大品种的合理性。在杂草抑制和无杂草产量方面，早期作物覆盖面积大是一个优势，在早期覆盖是基因型变异的结果的情况下，使早期覆盖成为比最终冠层高度更好的选择标准。未来的研究必须表明基因型和表型变异在早期覆盖率和最终冠层高度方面的相关性如何。