Abstract:

The length,width,shell thinckness and percentage of kernel of Ginkgo fruit-stone collected from more than 200 mother trees located whole-wide range were measured.The results showed that all of the characters,except for single fruit-stone weight,no significant differences among the climatic zones were observed,but the differences among populations (or locations) within a climatic zone and individuals within population were very significant.The variation coefficients for each of four characters varied from 3.0% for kernel rate to 21.3% for single pit weight.These data indicated that the genetic improvement of Ginkgo through individual selection within population should be more effective than among populations,and much than among the climatic zones.Because the adaptability is one of the most important traits for inten sive cultivation,the genetic improvement efforts should be within each climatic zone and do not carry out throughout whole range.

Key words: Ginkgo biloba, Breeding fruit-stone, Genetic variation