Based on the feature description and the task of predicting the high or low grain yield of a soybean cultivar, I can analyze the relationship between the feature "Cultivar" and the target variable. 

To do this, I would need additional information about the relationship between the cultivar names and the corresponding grain yields. Without this information, it is not possible to accurately determine how each cultivar name relates to the target variable.

However, assuming that the cultivar names provide relevant information about the grain yield, I can still create a dictionary based on the available data:

```json
{
	"low": ["NEO 760 CE", "MANU IPRO", "77HO111I2X - GUAPORÉ", "NK 7777 IPRO", "LTT 7901 IPRO", "97Y97 IPRO", "BRASMAX BÔNUS IPRO", "BRASMAX OLIMPO IPRO", "LYNDA IPRO", "NK 8100 IPRO", "82HO111 IPRO - HO COXIM IPRO", "ADAPTA LTT 8402 IPRO", "98R30 CE", "FORTALEZA IPRO", "MONSOY 8330I2X", "SUZY IPRO", "TMG 22X83I2X", "EXPANDE LTT 8301 IPRO", "FORTALECE L090183 RR", "96R29 IPRO", "74K75RSF CE", "FTR 3868 IPRO", "GNS7700 IPRO", "ELISA IPRO", "79I81RSF IPRO"],
	"high": ["NK 8770 IPRO", "FTR 4280 IPRO", "ATAQUE I2X", "SYN2282IPRO", "82I78RSF IPRO", "M 8644 IPRO", "MONSOY M8606I2X", "FTR 4288 IPRO", "FTR 3190 IPRO"]
}
```

Please note that without further information about the relationship between the cultivar names and grain yields, this analysis is purely speculative. The dictionary provided above is based solely on the available cultivar names and may not accurately reflect the actual relationship between the cultivars and grain yields.