Influence of intra-row cruciferous surrogate weed growth on crop yield in organic spring cereals

In the paper, the reference system is not explicitly mentioned. It appears that the reference treatment or baseline is the "weed-free plots" or the condition where surrogate weeds were not established. This serves as the control against which the effects of different experimental factors, such as nitrogen rate, inter-row spacing, and surrogate weed density, are being compared.In the experiment, surrogate weeds are manually removed from the inter-row zone to create a situation where only intra-row weeds remain to compete with the crop. This resembles the concept of a weed-free treatment achieved through labor-intensive methods like hand weeding. While the experiment doesn't exactly replicate a traditional hand-weeding approach, the intention is to minimize competition from weeds in the inter-row zone, similar to the way hand weeding achieves a weed-free environment. Therefore, the reference system in this case can be associated with the "Weed-Free Treatment (e.g., Hand Weeding)" category, albeit with some variations in the methods used.