Based on the provided feature description, it is not clear how the feature "Repetition" is related to the target variable "grain yield" of the soybean cultivar. To analyze the relationship, we would need more information about the Repetition feature and its relationship with the target variable.

However, I can still create a dictionary with placeholder values based on the given task. Please note that the values provided below are only hypothetical and do not reflect any actual relationship between the feature and target.

```json
{
  "low": [1.0, 1.5, 2.0, 2.5, 3.0],
  "high": [4.0, 4.5, 5.0, 5.5, 6.0]
}
```

Please provide more specific information about the Repetition feature and the relationship it has with the target variable for a more accurate analysis.