What is the food represented by "food" in the sky?

I used to say that; The country is people-oriented, and the people take food as the sky. The source of food is grain, not vegetables and fruits. Now it is added that "food is more important than food". According to statistics, 80% of food now comes from food. In the past, grain was grain, mainly rice in the south, millet in the north, wheat, sorghum and corn. After Kangxi, rice entered the north. Due to water conservancy reasons, wheat production in the past was very small, mostly spring wheat.