A worker soaks radish strips at TSL agricultural technology company in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history.

A worker puts vegetables into a jar at TSL agricultural technology company in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history.

Workers select radish strips at TSL agricultural technology company in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history.

Photo taken on Dec. 19, 2018 shows two dishes of "old jar vegetables" in Tongguan town of Changsha, capital of central China's Hunan Province. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history.

Cao Gang, manager of TSL agricultural technology company, checks the jars in storage in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history.

Cao Gang, manager of TSL agricultural technology company, checks the jars with pickled vegetables in the cellar of the company in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history.

A worker works beside the jars at TSL agricultural technology company in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history. (Photos: Xinhua)

A worker checks the automatic water supply system in the cellar at TSL agricultural technology company in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history.

A worker stirs pickled radish strips at TSL agricultural technology company in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history.

A worker checks the cellar at TSL agricultural technology company in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history.