Wheat is an affordable crop with a correspondingly modest yield. Its buying price and harvest revenue both fluctuate a bit more than Corn, but less so than Cotton and Peanuts.
If the Wheat Harvest Fails, all wheat crops are lost. If the player owns a Crop Insurance, he will be financially compensated for this loss.
Wheat will also be lost in a Dry Season event, but here, either a Well or a Crop Insurance will protect him.
As with other crops, revenue from wheat will increase whenever a Good Season or Splendid Harvest annual event occurs.
If there’s a Civil War, roughly 75% of all wheat (and other crops) will be lost.
The Market Prices Drop and Crash of the National Bank events both result in lowered crop revenues, down to around a third of the usual yield.
All tools that the player owns, will improve revenue from crops, including wheat. The bonus from tools is displayed on the Annual Report.
According to this site, wheat is main source of protein in developing countries:
WikiPedia entry for Wheat:
Facts about wheat and world maps of wheat farming and consumption: