Morphogenesis Of Epiphyllous Female Reproductive Organ And Characteristic Analysis Of Mature Seed On 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 1981. As a special germplasm in Ginkgo biloba L. family, Ginkgo biloba L. var. epiphylla Mak. had great academic and ornamental values. Using the technology of paraffin section, the morphogenesis of epiphyllous female repeoductive organ and the characteristics of its mature seeds are studied, taking Ginkgo biloba L. var. epiphylla Mak. from Zhongzhuang township, Yiyuan county, as testing material, and the normal Ginkgo biloba L. from Laojuntang, Taian city as control. And the results showed:(1) The morphogenesis of epiphyllous female repeoductive organ (EFRO) of Ginkgo biloba L. var. epiphylla Mak.. The EFRO appeared on the leaves of spur at the early stage of leave expansion on April 12th, which shape formed on May 24th, meanwhile, the collar developed. The exopleura turned to green and matured at the last 10 days of August, and the seeds totally matured at the last 10 days of Septemper. There was metachronous on the development of EFRO.(2) Anatomy of EFRO of Ginkgo biloba L. var. epiphylla Mak.. The anatomy showed that the initial stage of EFRO was some cells arranged densely, with the distribution of secretory cavity and vascular bundle. On May 31st, Differentiation of nucellus and integument of EFRO appeared, and the integument occurred level differentiation. The nucellus started to thicken on 14^th, June. On July 5^th, thearchegonium appeared in thenucellus. Throughout thedevelopment process of EFRO, theobvious micropyle, pollen chamber, megasporocyte and tetrad were not found. The EFRO development can be divided into ^three stages: thedevelopment period of secretory cavity and vascular, differentiation stage of nucellus and integument, thestage of archegonium.(3) The number and thelocation of thearchegonium of EFRO are uncertain. The number of EFRO is usually 1, seldom 2 or 3. The locations for archegonium are usually as follows: micropylar end, chalazal end, one side of micropylar end and one side of chalazal end. There are 1 or 2 (usually 1) layers mantle cells bounding thearchegonium, theneck cells and central nuclear are not obvious(4) The research of theseparation characters of mature seeds of EFRO. It can be divided into 3 stages of theseed separations: prophase, metaphase and anaphase. The net weights of mature seeds centralize at 1.5-2.5g and 2.5-3.5g. 1109 seeds were collected from September 15^th, to October 10^th, and theaverage seed falling of every day is 48. The heaviest seeds is 6.24g averagely (September 16^th), while thehighest given nut rate is 35.57% averagely (September 22^nd), and thegiven kernel rate is 64.17 %( October 5^th).