Researches On Seed Nucleus' Variation Of Ginkgo Trees In Badong, Hubei Province

Originated from China, Ginkgo biloba is one of the oldest remained tree species in gymnosperm with great economical and scientifical value. Badong County of west-south Hubei Province is one of the three major distribution areas of ancient Ginkgo trees in Hubei. In this paper, seed samples were collected from 100 Ginkgo trees in Qingtaiping Town, Yesan'guan Town, Shuibuya Town and Chadianzi Town of Badong County, and the variation of seed nucleus' characters and substances content were studied. It provided the theoretical basis for the evaluation and quality identification of germplasm resources and selection breeding of seed-used Ginkgo. Major results were as follows:(1) There were four types of seed nucleus in Badong, i.e. Meihe type, Maling type, Fozhi type and Yuanzi type, no Changzi type. Most Ginkgo trees belonged to Meihe type.(2) Very significant differences existed among Ginkgo individuals in seed nucleus' length, width, length/width, thickness/width, single seed weight, kernel rate and seed nucleus' surface characters. The variation extent decreased in sequence of single seed weight > length > length/width > width > thickness >kernel rate> thickness/width. This showed that single seed weight had the biggest improving potential, while kernel rate had the least.(3) There were very significant differences in the content of seed nucleus' water, organic nutritional matter and mineral elements. The substances content decreased in sequence of starch>crude protein>water>soluble sugar>N >K >P >Mg >Ca >Fe >Zn >Cu >Mn, while the variation extent decreased in sequence of Fe >Zn >Ca >Mg >soluble sugar>Mn>P>Cu>crude protein(N)>water>starch>K. This showed that it was easier to improve the content of soluble sugar, Ca and Fe than starch, K and Cu during the selection breeding of seed-used Ginkgo.(4) The variation of seed nucleus' characters and substances content in Badong County were mainly distributed within areas.(5) The clustering analysis showed that Ginkgo individuals could be clustered into 5 groups based on seed nucleus' characters.(6) The correlation analysis among seed nucleus' characters showed that selecting the long nuclear variety was helpful to improve the single seed weight, kernel rate and germination rate.(7) The correlations among seed nucleus' substances content were very complex. We should make the best plan according to these correlations in the determination of objective traits. (8) The correlation analysis between seed nucleus' characters and substances content showed that selecting longer or thicker seed nucleus was helpful to improve the protein content. Selecting wider or thicker seed nucleus was helpful to improve the content of K and Fe. Selecting seed nucleus with higher thick-rate was helpful to improve the content of Cu. Selecting seed nucleus with higher weight was helpful to improve the content of protein and most major element, while possibly decreased the content of soluble sugar and Cu. The improvement of seed nucleus' kernel rate and starch content had little significance.(9) The first 20 individuals for different use were respectively selected out based upon indexes as follows: length/width, single seed weight, kernel rate, the content of organic nutritional matter, major element and trace element. Based on comprehensive consideration of the variation of seed nucleus' characters and substances content, some Ginkgo individuals were primary selected for further research.