Based on the given feature description, the NLP (Number of stems) is a numeric variable that represents the count of stems in a soybean cultivar. To analyze its relationship with the task of predicting the grain yield, we can use our prior knowledge of soybean cultivation.

In general, a higher number of stems in a soybean cultivar indicates a better potential for higher grain yield. More stems provide more opportunities for flowers to be pollinated and develop into pods, ultimately leading to a higher yield. On the other hand, a lower number of stems could suggest poor growth conditions or disease infestation, resulting in a lower grain yield.

Based on this analysis, we can create a dictionary with the possible values of NLP for each target class:

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

In this example dictionary, we provide five typical NLP values for each target class. The values depicted are floats, and the ranges can be adjusted based on specific domain knowledge and data analysis.