Based on prior knowledge and the given feature description, it is reasonable to assume that the plant height (IFP) can have an impact on the soybean grain yield. A higher plant height often indicates better growth and potentially higher grain yield. 

To analyze the relationship between IFP and grain yield, we need additional information about the target variable (grain yield) to determine the appropriate ranges of values for IFP. Without this information, we cannot provide specific ranges for low and high grain yield.

However, to create a dictionary with 5 typical IFP values for each target class ('low' and 'high'), we can make some assumptions and provide an example. Remember, these values are hypothetical and may not reflect the true relationship between IFP and grain yield:

```json
{
	"low": [25.2, 26.8, 23.1, 27.5, 24.9],
	"high": [32.6, 31.2, 33.9, 30.5, 34.1]
}
```

Please note that these values are examples and should not be considered as accurate estimations without further analysis and domain-specific knowledge.