Based on the provided information, the feature "Cultivar" can be used to predict the grain yield of the soybean cultivar as low or high. To analyze the relationship between the feature and the target, we can look at the different cultivar names and their associated grain yield characteristics.

After analyzing the data, we can create a dictionary that lists the cultivar names for each target class:

```json
{
	"low": ["NEO 760 CE", "MANU IPRO", "77HO111I2X - GUAPORÉ", "NK 7777 IPRO", "LTT 7901 IPRO", "BRASMAX BÔNUS IPRO", "97Y97 IPRO", "BRASMAX OLIMPO IPRO", "PAULA IPRO"],
	"high": ["GNS7900 IPRO - AMPLA", "NK 8100 IPRO", "82HO111 IPRO - HO COXIM IPRO", "83IX84RSF I2X", "ADAPTA LTT 8402 IPRO", "98R30 CE", "FORTALEZA IPRO", "MONSOY 8330I2X", "SUZY IPRO", "TMG 22X83I2X", "EXPANDE LTT 8301 IPRO", "FORTALECE L090183 RR", "LAT 1330BT", "FTR 4280 IPRO", "ATAQUE I2X", "SYN2282IPRO", "82I78RSF IPRO", "M 8644 IPRO", "MONSOY M8606I2X", "NK 8770 IPRO", "FTR 4288 IPRO", "FTR 3190 IPRO"]
}
```

Note: The list of cultivar names for each target class is based on the provided feature description. The actual accuracy of this prediction may depend on various other factors not included in the given information.