Problem description:

When did cotton begin to be planted? What is its development history?

Analysis:

Cotton planting has a long history, which began around 800 BC. China is one of the countries that planted cotton earlier in the world. In the 3rd century BC, that is, during the Warring States Period, there were records about cotton planting and textile in China in Shangshu and Houhanshu. ?

In the history of cotton planting in China, four cultivated varieties have been planted: island cotton (long-staple cotton), Asian cotton (coarse-staple cotton), upland cotton (fine-staple cotton) and grass cotton (coarse-staple cotton). In different historical periods, the main cultivated varieties in China are also different. Asian cotton has the longest introduction history, the longest planting time and a wide planting area. Upland cotton was introduced into China for a short time, but it developed rapidly, replacing Asian cotton in 1950s. At present, most of the cotton planted in the vast cotton areas is upland cotton (fine wool cotton), and a small amount of island cotton (long wool cotton) is also planted in Xinjiang.