Based on my prior knowledge, the feature 'IFP, plant height' could potentially have a relationship with the grain yield of the soybean cultivar. Here's the analysis:

1. High IFP values may indicate healthy growth and development of soybean plants, which could lead to higher grain yield. Therefore, we might expect higher IFP values to be associated with a high grain yield.

2. Low IFP values may indicate stunted growth or other issues with the soybean plants, which could result in a lower grain yield. Hence, lower IFP values might be associated with a low grain yield.

Based on this analysis, I will create a dictionary with IFP values for each target class:

```json
{
	"low": [20.5, 22.3, 19.8, 21.1, 18.9],
	"high": [30.7, 29.4, 31.2, 28.9, 30.1]
}
```

Please note that the actual values may vary depending on the specific dataset and domain knowledge.