Based on the provided feature description, it seems like the Repetition feature may not directly indicate the grain yield of the soybean cultivar. However, I will assume that there might be some correlation between the repetition of cultivating a certain soybean cultivar and its grain yield.

To analyze the relationship between the Repetition feature and the grain yield task, we would need more information or data. Without specific data, it is challenging to determine the appropriate ranges of values for the Repetition feature and its relationship to grain yield.

However, I can still provide an example of the requested dictionary format:

```json
{
	"low": [1.0, 2.0, 1.5, 1.2, 2.5],  
	"high": [3.0, 4.0, 3.5, 2.8, 5.0]  
}
```

Please note that the provided example values for Repetition are arbitrary and do not represent a real relationship between the Repetition feature and grain yield. To get accurate results, it is crucial to have proper data and analysis specific to the soybean cultivar and the grain yield task.