Based on prior knowledge, the number of grains per pod (feature NS) can have a significant impact on the grain yield of soybean cultivar. Generally, a higher number of grains per pod implies a higher grain yield, while a lower number of grains per pod indicates a lower grain yield.

To create the dictionary, I will assume the following ranges of values:
- Low NS: values less than or equal to 5
- High NS: values greater than 5

Here is the generated dictionary:

```json
{
	"low": [4.5, 3.2, 2.8, 4.1, 5.0],
	"high": [6.3, 5.8, 7.2, 6.5, 8.1]
}
```

Please note that the values provided above are just example values and should not be considered as actual data. The actual values will depend on the specific soybean cultivar and the data available.