Based on the provided information, there are two key features that can be analyzed to determine the grain yield of the soybean cultivar: "Seeds per meter/linear" and "Density per meter/linear". The higher the number of seeds and density, the higher the grain yield is likely to be. 

Here's the dictionary with the possible values of the "Cultivar" feature for each target class:

```json
{
	"low": ["NEO 760 CE", "MANU IPRO", "77HO111I2X - GUAPORÉ", "NK 7777 IPRO", "LTT 7901 IPRO", "96R29 IPRO", "74K75RSF CE", "FTR 3868 IPRO", "ELISA IPRO", "NEO 760 CE"],
	"high": ["GNS7900 IPRO - AMPLA", "97Y97 IPRO"]
}
```

Please note that the "low" class has multiple cultivar values, while the "high" class only has two cultivar values.