Based on the given information, the feature is IFP (plant height) and the task is to determine the grain yield of a soybean cultivar as either low or high. 

Analysis:
Since the feature description provides information about plant height, it can be inferred that taller plants may have a higher potential for grain yield. Therefore, it is likely that higher IFP values would be associated with a high grain yield.

To create the dictionary, we need to provide 5 typical IFP values for each target class ('low' and 'high'). However, without specific information about the target variable, it is challenging to determine the appropriate ranges of values for 'low' and 'high'.

Assuming that the target variable is continuous (e.g., grain yield in tons/ha) rather than categorical, we can still provide a general analysis:

Dictionary: 

```json
{
	"low": [3.4, 3.8, 4.1, 4.5, 4.9],
	"high": [5.3, 5.7, 6.0, 6.4, 6.8]
}
```

Note: The provided IFP values are only hypothetical and may not accurately represent the relationship between IFP and grain yield. The actual values would depend on the data and the specific crop studied.