Abstract: China possesses more than 70 % ginkgo resources in the world. The primary problems existing in ginkgo cultivation are : (1) no big-grain and fine nucleus-used cultivars ; (2) no known genetic law of primary characters ginkgo seed. The purposes of this research are to collect 50 nucleusused cultivars from 12 provinces in China , to carry out genetic analysis for economical character and
multiple character selection on ginkgo seed. The results of analysis show that maxmum single nucleus weight , stone mass/ fruit mass ( %) and kernel mass/ stone mass ( %) are 3. 89 g , 33. 58 % and 82. 49 % , respectively. The heritability ( h2) of single nucleus mass is 0. 9759. The genetic correlation coefficient ( rG) between nucleus2shape coefficient and single nucleus mass , and direct genetic path coefficient ( PY·i) of single fruit mass to single stone mass are 0. 9986 and 1. 407 , respectively. Twelve provenances from China are divided into four classes. Three fine nucleus-used cultivars are selected out through index or direct selection methods from fifty nucleus-used cultivars in China. The theory of nucleus2used cultivar selection was studied in this paper.

Key words: Ginkgo biloba L., Nucleus-used cultivars, Genetic analysis, Index selection