Licorice Sexual Reproduction And The Reproduction Of The Abortive Preliminary Study

As we all konw,the Glycyrrhiza uralensis Fisch. seeds come from the wild, under natural conditions the setting rate of licorice seeds was only about10%-20%.If we can find the reason of the licorice seeds’low setting rate under natural conditions, and take proper manual intervention, then the licorice seeds’ setting rate can be increased substantially. This thesis aimed at solving the problem of the licorice seeds’ low setting rate and high abortion rate under natural conditions. On the one hand, the thesis discusses the matter from the perspective of anatomia, using Liquorice flower at different developmental stage and those under artificial pollination as the experimental object, taking conventional parafin section method to study the sexual reproduction process of licorice. On the other hand, from the macroscopic angle, this thesis use quadrat survey to investigate the level of flower and pod abscission and the seeds’ abortion rate under natural condition at the stage of young pod, combined with laboratory analysis, exploring the reason of flower and pod absicission and seeds’abortion.The following is the main results:1.By observing the extenal formand the exchanges of internal structure of Licorice bulbil underground, the licorice flower bud’s initial period and the type of differentiationhave been cleaned.When the licorice’s underground bulb grow to the soil surface, the growth points of both sides differentiate from differentiating scale primordium into differentiating compound leaf primordium. Besides this research also find that all the flower bud were born on the nod of the compound leaf, and all the shoot bud were born on the nod of metamorphosis leaf.The growth points of the licorice’s underground bulb showed the status that "the growth and differentiation"were conducted at the same time, the growth point of the scale bulb divided upword and the growth point on the side differentiated into leaf primordium synchronously. It is suggested that the licorice flower flower annually, and the differentiation type is differention once per year.2.By observing the licorice flower bud under the microscope, the form change characteristics of licorice flower bud differentiation process has been cleaned.According to the change of licorice axillary bud tip shape,the licorice flower bud differentiation process can be divided into five main periods:the undifferentiation period, the inflorescence primordium differentiating period, the bracts and small flower primordium differentiating period, the floral organ primordium differentiating period, and the bracts formative period.Among them, the inflorescence primordium differentiating period can be divided into4periods:Sepal primordium differentiation, Corolla primordium differentiation, Stamen primordium differentiation, and Pistil primordium differentiation.3.By surveying the liquorice plant first inflorescence section, the licorice flower bud differentiation initial section distribution characteristics has been cleanedAccording to the research,the Licorice flower bud differentiation of initial section distribution present the characteristic of "Middle high and two low".In detail,the seventh, eighth, ninth nod location has the highest rate of flower bud appearance when calculated from the nod location where the first licorice compound leaf borned in, and the percentage can reach67%. The fifteenth, sisteenth, and the seventeenth nod location has the highest rate of flower bud appearance when calculated from the nod location where the scale bulb borned in, and the percentage can reach50%.Through the observation of parafin section at different developmental stages, licorice’s growth period can be divided into five main periods, the undifferentiation period, the inflorescence primordium differentiating period, the bracts and small flower primordium differentiating period, the floral organ primordium differentiating period, and the bracts formative period.4.Through the Glycyrrhiza uralensis flower paraffin section observation of different development period,we clear the development characteristics in the process of Glycyrrhiza uralensis embryonic developmentThe Glycyrrhiza uralensis has a single carpel pistil, a single room ovary, multiple ovules, campylotrop, bi-integument, thick nucellus, embryo sac develop to smartweed type. After two times of meiosis, the megaspore mother cell which directly derived from the early new sporogenous cells form four megaspore in a straight line array, in which only the megaspores in chalaza point continue to develop functional megaspores.Functional megaspores directly develop to mononuclear embryo sac.After several mitosis,Mononuclear embryo sac forms two nucleus, four and eight nuclear embryo sac in turn.eight nuclear embryo sac occurs to cellularization and finally forms mature embryo sac structure which has seven cells and eight nuclear.The Glycyrrhiza uralensis flowers have diadelphous stamen which nine stamens are united, one stamen independent. Anther wall is made up of skin, endothecium, middle lamella, tapetum, its development belongs to the dicotyledonous type. After reduction mitosis, Glycyrrhiza uralensis microspore mother cell forms microspore tetrad, its cytokinesis type is the same time type. With callus around tetrad dissolved gradually, Microspore tetrad dispersed into four small microspores.Through unequal mitosis, Mononuclear microspore in the late uninucleate stage forms a germ cell and a vegetative cell. Glycyrrhiza uralensis mature pollen grains is two cells type.The male flower and female flower development of Glycyrrhiza uralensis are not synchronized. The Glycyrrhiza uralensis stamen development is earlier than The Glycyrrhiza uralensis pistil development. In addition, Glycyrrhiza uralensis flowers open process and stamen development process is out of sync. When Glycyrrhiza uralensis flowers have not opened, the anther has began to release powder. When Glycyrrhiza uralensis flowers open, the majority of anther has loose all powder.Before Licorice flower fertilizated, the two central polar nucleus cling to each other closely, and close to egg apparatus gradually. The reproductive organ divide into two Sperm cells after go into pollen tube, one Sperm cell combines with egg cell become zygote, the other Sperm cell combine with two polar nucleus become primary Endosperm nuclear. The zygote divide into two cell proembryo, four cell proembryo, eight cell proembryo and multicellular proembryo by mitosis, forming a complete Cotyledons form embryo finally. The primary Endosperm nuclear divide into free endosperm.then the free endosperm go through cell differentiation and become endosperm with cell style.5. Investigate deeply the degree of licorice reproductive abortion under natural conditions and preliminarily probes into the reasons of licorice reproductive abortion Under natural conditions liquorice flowers fall off rate of three samples is47.41%,58.86% and57.21%respectively, the average fall off rate reached54.67%, that is more than half of liquorice flowers fell off in the process of growth and development, not formed a seed. Among them, the upper liquorice plant flowers fall off rate is the worst, at59.78%. Under natural condition licorice seeds average abortion rate is as high as49.68%; the ovule abortion rate is30.4%which is significantly higher than embryo abortion rate which is19.28%. The further research indicate that, the abortion of basal ovule of licorice flower ovary is the most serious, it is the same wih the embryo abortion of upper part of the ovary, abortion rate is42.39%and23.34%respectively. Under natural condition, when most licorice flowers come out, the stigmas have received plenty of pollen.It is suggested that, the quantity of pollen is not the main impacter of reproductive abortion of liquorice flower. When vexilla open, keel without cracking stage, licorice has finished about90.00%powder loosing, whichindicate that most liquorice flower stigma accepts dark yellow pollen that is left behind after flower finished loosing powder. The above analysis shows that licorice flower stigma accepting very low activity pollen is the reason that licorice floret with pollen falling off and partial ovule of ovary fertilization unsuccessful.Study characteristics and innovation:(1) we have determined the licorice flower bud differentiation’s beginning period, types、 initial differentiated section distributionand characteristics of the differentiation process;(2)We find hat licorice floret have begun loosing pollen before flowers open, and finshed when flowers open;(3)Investigate the degree of licorice reproductive abortion and abortive pattern under natural conditions, and find that licorice flower stigmas received low activity pollen may be the reason of sticky pollen licorice flowers fall off and the ovary can not be successfully fertilized.