Based on the provided feature descriptions and task, we can analyze the relationship between the cultivar and grain yield of the soybean. 

To determine how high the grain yield is, we will look for patterns and relationships between the cultivar names and the target class of high or low grain yield. We cannot determine the exact grain yield for each cultivar, but we can identify the cultivars that are more likely to have a high grain yield based on the given information. 

Here is the generated dictionary:

```json
{
  "low": [
    "NEO 760 CE",
    "MANU IPRO",
    "77HO111I2X - GUAPORÉ",
    "NK 7777 IPRO",
    "GNS7900 IPRO - AMPLA",
    "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",
    "96R29 IPRO",
    "74K75RSF CE",
    "FTR 3868 IPRO",
    "GNS7700 IPRO",
    "ELISA IPRO",
    "79I81RSF IPRO",
    "NEO 790 IPRO",
    "PAULA IPRO",
    "FTR 3179 IPRO",
    "LAT 1330BT",
    "FTR 4280 IPRO",
    "ATAQUE I2X",
    "SYN2282IPRO",
    "82I78RSF IPRO",
    "M 8644 IPRO",
    "MONSOY M8606I2X",
    "NK 8770 IPRO",
    "FTR 4288 IPRO",
    "FTR 3190 IPRO"
  ],
  "high": [
    "96R29 IPRO"
  ]
}
```

Please note that the list of the target class "high" only contains one cultivar, "96R29 IPRO", as it is the only cultivar mentioned with a higher seed per meter/linear value of 21.9. All other cultivars do not have specific details indicating a high grain yield.