Based on the given feature and task, the relationship between the feature "Cultivar" and the target variable "grain yield of soybean cultivar" can be analyzed as follows:

- There is no direct information given about the relationship between the "Cultivar" feature and the target variable "grain yield". However, it is possible to identify patterns based on the other feature descriptions.

- The feature "Maturation group" provides information about the maturation group of the soybean cultivar. It is not clear how it directly relates to grain yield, but it can be considered as a potential indicator.

- The features "Seeds per meter/linear" and "Density per meter/linear" provide information about the number of seeds and the density of the cultivar per meter/linear length. These features can be good indicators of high grain yield, as more seeds and higher density can potentially lead to increased yield.

- It is important to note that the above analysis is based on prior knowledge and assumptions. Further analysis or field experiments would be required to establish a more accurate relationship between the "Cultivar" feature and the target variable "grain yield of soybean cultivar".

Based on the above analysis, the dictionary with the specific details can be generated as follows:

```json
{
	"low": ["NEO 760 CE", "MANU IPRO", "77HO111I2X - GUAPORÉ", "NK 7777 IPRO", "LTT 7901 IPRO", "BRASMAX BÔNUS IPRO", "97Y97 IPRO", "BRASMAX OLIMPO IPRO", "LYNDA IPRO", "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"],
	"high": ["FTR 3190 IPRO", "FTR 4288 IPRO", "NK 8770 IPRO", "MONSOY M8606I2X", "M 8644 IPRO", "ADAPTA LTT 8402 IPRO", "98R30 CE", "FORTALEZA IPRO", "MONSOY 8330I2X", "SUZY IPRO", "TMG 22X83I2X", "EXPANDE LTT 8301 IPRO", "FORTALECE L090183 RR", "83IX84RSF I2X", "82HO111 IPRO - HO COXIM IPRO", "82I78RSF IPRO", "SYN2282IPRO", "ATAQUE I2X", "NK 8100 IPRO", "FTR 4280 IPRO", "LYNDA IPRO", "BRASMAX OLIMPO IPRO", "LAT 1330BT", "FTR 3179 IPRO", "97Y97 IPRO", "BRASMAX BÔNUS IPRO", "PAULA IPRO", "NEO 790 IPRO", "LTT 7901 IPRO", "GNS7900 IPRO - AMPLA", "79I81RSF IPRO", "ELISA IPRO", "NK 7777 IPRO", "77HO111I2X - GUAPORÉ", "GNS7700 IPRO", "FTR 3868 IPRO", "MANU IPRO", "NEO 760 CE", "74K75RSF CE", "96R29 IPRO"]
}
```