i think the qustions says it all
“Seed corn planted in adequate moisture and temperature will emerge in about one week. However, in a cold spring, emergence can take as long as three to four weeks after planting.” (Dyer County Extension)
It seems radish seeds take between 3 and 7 days. (Radiant Radish Seeds & Academic Authorings: The Research Paper)
Radishes are like the fastest growing food plant. They can be harvested in as little as 23 days after planting.