However, based on the historical context of plantations in the American Southeast, the most likely answer is wheat.
Here's why:
* Cotton, rice, and indigo were the major cash crops of the Southern plantation economy.
* Wheat was not typically grown on large plantations in the Southeast. While some small farms might have grown wheat for local consumption, it was not a significant cash crop for the region.
It's important to note that the term "plantation" can have different meanings depending on the time period and location. If the question is referring to a specific plantation or a specific era, the answer might be different.