Studies On Reproductive Biology Of Caragana Korshinskii Kom.

Caragana korshinskii Kom,belong to the family Leguminous,the genus Caragana perennial shrub species,were the main species initially employed for vegetation restoration in desert areas in China.It naturally distributed in Shaanxi,Inner Mongolia,Shanxi,Gansu,Ningxia,Xinjiang,in abroad,only distributed in Mongolia.It had strong vitality and resistance to drought,bitter cold and torridness.It became the optimization shrubs for ecological environmental construction and prevention,harnessing of desert and the development of livestock husbandry.Megasporogenesis,microsporogenesis,female and male gametophytes development in C.korshinskii were observed using method of traditional paraffin sections.The main results were as following:The ovary is monolocular,monocarpellary,anatropous ovule,two integument and tenuinucellatae.Archesporial cell differentiated below the nucellar epidermis and developed into megaspore mother cell(MMC).Later,MMC undergent meiosis to form a linear tetrad.One megaspore at chalazal end developed into mononucleate embryo sac.The development of embryo sac was Polygonum type.The mature embryo sac consists of two synergids and one egg near the micropyle,a central cell in the center of embryo sac,three antipodal cells in the chalaza.The clavate papilla cells on the surface of the stigma and anatropous ovules were observed by a scanning electronic microscope(SEM).Microsporogenesis and male gametophyte development of were normal.The anther had four chambers;the development of anther wall was the Basic type,which consisted of four or five layers,i.e.an epidermis,an endothelium,one or two middle layers and a tapetum.The tapetum was of a glandular type.The meiosis of microspore mother cells were simultaneous type,tetrads were mostly tetrahedral while some are symmetrical.The mature pollen grains were of a binuclear type.The mature pollen grains were observed by SEM,which appeared spherical in shape,and the exine is almost smooth.The breeding system of C.korshinskii was investigated and analyzed through a field investigation.The flowers were typical papilionaceous.In May,it came into flowering period.Flowering time of single flower lasted 5 to 7 days and single plant lasted 20 to 25 days.They were the night-and day-blossoming flowers.Flowering intensity during the day is far greater than at night.Blossoming intensity peak were from 10 a.m.to 4 p.m.There were two types of flowers in population,long-pistillate and short-pistillate flower.Sometimes one plant had two types of flowers.Based on the result of out crossing index,the breeding system mainly was outcrossing,part was self-compatible,needs pollinators during the pollination.