Analysis Of Variation Characteristics Of Ginkgo Biloba Var.epiphylla Mark

Ginkgo biloba L. is the only relict seed plant suffering the quaternary glaciation. Variations happened to the leaves and the seeds of Ginkgo biloba L. during its long evolution process. The first Ginkgo biloba L. var. epiphylla Mak. was discovered by Shirai in Japan at 1891. As a special germplasm in Ginkgo biloba L. family, Ginkgo biloba L. var. epiphylla Mak. had great academic and ornamental values.Taking Ginkgo biloba L. var. epiphylla Mak. as testing material, studied the variation characteristics of Ginkgo biloba var.epiphylla Mark from morphological representation, chromosome karyotype and anatomy characters.And the results showed:The mature seeds taken from five Ginkgo biloba var.epiphylla Mak. trees which are in Yiyuan Shandong were studied in this paper. This study found that seeds of the Ginkgo biloba var.epiphylla Mak. had various shapes, smaller than normal seed 1/2-1/4, back convex ventral flat; 1/5-3/5 of the upper part within nut was "cavity", the wing was not obvious; The micropylar region of endotesta was brown, showing atrophy, fold or nondevelopment; kernel had various shapes and relatively smooth. The result showed that: the seed weight and nut weight were 3.72g, 0.79g, respectively;the percent of nut/ fruit and kernel/ fruit were 21.40%, 48.5%, respectively. The karyotype of 28 Ginkgo biloba var.epiphylla Mak.germplasms which came from Japan and Shandong were studied by method of squash with the young leaves. The results showed that all the chromosomes were diploid, the chromosome number could be described as 2n=2×=24, the karyotype was mainly composed of median centromere chromosome(m), nearly median centromere chromosome(sm) and subterminal region(st);there were satelittes in 6 germplasms. The variance's analysis shows that there was significant difference between SY2 and other germplasms on length ratio of chromosome which was 3.97, the asymmetrical karyotype coefficient and average arm ratio differs greatly among germplasms. GX3 and HB were more maximum than other germplasms, while the evolution extent of NS2 was originative.The initiation of epiphylla ovule of Ginkgo biloba var.epiphylla Mark. is the increasing of layer number and cell volume. Micropyle of Ginkgo biloba var.epiphylla Mark. appeared mid of May,harf to one month later than pollination time without pollination drop and micropylar is narrow,pollen chamber is aplasia,all of these caused Ginkgo biloba var.epiphylla Mark. could not fertilize at time and structure.The conoid which appeared mid of May degradated mid of June and the volume becomed smaller ,which caused a cavity appeared between conoid and mesoperm from upper and lower. Ginkgo biloba var.epiphylla Mark.did not fertilize ,but there was growth and development of integument tissue in Ginkgo biloba var.epiphylla Mark. and the later had many secretory cavity and the initial cell cluster of secretory cavity.The development of integument is similar to that of normal Ginkgo biloba L. except that harf a month later tahan normal Ginkgo biloba L.