Selection of superior trees of Vernicia fordii in the northern distribution margin description of the major traits
To advance Vernicia fordii industry and solve the problem of lacking superior trees in the northern distribution margin of tung oil tree, selection of superior tung oil trees has been conducted in Tongcheng County and Jinzhai County of Dabie Mountain since 2011. Five superior trees named as Tongcheng 1, Tongcheng 2, Jinzhai 1, Jinzhai2, and Jinzhai 3 were identified through a serial of process including resource investigation, preliminary selection, repeated selection, and final selection. The proportion of male and female flowers in all selected trees was within1:10 and the flowers could be classified as less flower inflorescence type. All trees except Jinzhai2 produced big and uniform fruits with thin smooth fruit skin and the seed oil rate was above 50%. An average yield per unit crown area could reach to 1.25 kg·m-2. All those parameters met with the standard of selecting Vernicia fordii superior trees in China. These superior individual plants could provide a basis for developing elite varieties in the northern distribution margin in China.