Barley is not one of the top five food staples in the world, contrary to wheat, maize, and rice. Here's an explanation:

1. Wheat:
Wheat is one of the most widely cultivated and consumed staple crops globally. It is a major source of carbohydrates and provides a significant portion of the daily calorie intake for a large population. Wheat is used for making various food products such as bread, pasta, and pastries.

2. Maize (Corn):
Maize, or corn, is another important staple crop worldwide. It is a versatile grain and can be consumed in various forms, including as whole kernels, flour, or processed into products like cornmeal or corn oil. Maize is not only used for human consumption but also serves as animal feed and a raw material for various industries.

3. Rice:
Rice is a staple food for a significant portion of the global population, particularly in Asia. It is a primary source of nutrition and energy for billions of people. Rice is consumed as a main dish, side dish, or used in the production of other food products like rice flour or rice bran oil.

4. Barley:
While barley is a widely cultivated crop, it is not considered one of the top five food staples in the world. Barley is commonly used as animal feed, particularly for livestock such as cattle and poultry. It is also used in the production of malt for brewing beer and whiskey. However, its consumption as a staple food by humans is relatively limited compared to wheat, maize, and rice.

5. Other food staples:
Apart from wheat, maize, and rice, other crops that are considered major food staples include potatoes, cassava, and millet. These crops are widely cultivated and consumed in different regions of the world, providing essential nutrients and energy for a significant portion of the population.

In conclusion, while barley is an important crop with various uses, it is not considered one of the top five food staples in the world. Wheat, maize, and rice are the primary crops that provide a significant amount of energy and nutrition to a large population globally.