What farm commodity is referred to as "yellow jewel" by the Chinese?

The term "yellow jewel" refers to soybeans, particularly in the context of Chinese agriculture and cuisine. Soybeans have been a vital part of agricultural practices and are highly valued not only for their nutritional content but also for their versatility in various products, including tofu, soy sauce, and cooking oils. The term highlights the importance of soybeans in the Chinese diet and economy, as they are often considered a precious commodity for both human consumption and livestock feed.

In terms of the other options, while rice is a staple grain in China, it is typically associated with a different cultural significance. Corn, although crucial in many agricultural contexts, is not commonly referred to in terms of its color as a "jewel." Barley also plays a role in agriculture, especially in beer and livestock feed, but it does not hold the same level of prestige as soybeans within Chinese agriculture. Thus, soybeans being referred to as the "yellow jewel" emphasizes their economic and cultural importance in China.