People of Lisu ethnic group peel walnuts at a workshop of a resettlement site in Daxingdi Town, Lisu Autonomous Prefecture of Nujiang, southwest China's Yunnan Province, June 24, 2019. (Xinhua/Qin Qing)

Southwest China's Yunnan Province has developed a walnut gene pool with a total of 2,005 walnut germplasm collections.

The gene pool is believed to be the largest genebank for the Juglans sigillata collections, also called iron walnut, said Wang Weibin, deputy chief of the provincial forestry and grassland bureau.

The genebank is part of the forestry germplasm resource preservation system developed by the province.

To promote the ecological protection and industrial development of the forestry and grassland, the province has set up 5,551 tree seed production bases with a total area of 55,200 hectares, Wang said.

Yunnan has more than 800 years of history of growing walnuts. At the end of 2017, more than 90 percent of the cities and counties in Yunnan grew walnuts.