Biological Characteristic Comparison Research Between Fructiferous And Acarpous Lagerstroemia Indica

Lagerstroemia indica is a deciduous shrub or small tree of lythraceae of Lagerstroemia and our country’s important garden flower tree, Which not only has beautiful tree gesture, long flowering period, rich color and other characteristics, but also has the resistance ability against pollution and adsorbs harmful gases and dust. The flowering period of Lagerstroemia indica is so long that some will form fruits and consume large amounts of nutrients in the flowering stage, which affects the formation of late flower bud, and reduce the ornamental value, therefore, Hunan Academy of Forestry bred a no fruit crape myrtle named "Xiang Yun".The objects of the study are Fructiferous Lagerstroemia indica "Hong Ye" and Acarpous Lagerstroemia indica "Xiang Yun" with four years old, whose growthform is similar inside the garden in Hunan Academy of Forestry. The morphological differences in the flower bud differentiation process of two varieties of Lagerstroemia indica are studied through the way of observation and measurement; The pollen’s viability and stigma’s receptivity are measured by the method of liquid cultivation and fluorescence microscopy; The differences between two varieties of Lagerstroemia indica in flower organ differentiation process are studied by conventional paraffin section method; The changes of endogenous hormones in the buds of two varieties of Lagerstroemia indicain flower organ differentiation process were determined by Enzyme-linked Imunosorbent Assays(ELISA).Then, the correlation between infertility and the changes of endogenous hormones was discussed to find the reasons for fruitless of "Xiang Yun". The conclusions of all research above are as follows:(1) Fructiferous and Acarpous Lagerstroemia indica has individual differences. The leaves of Acarpous Lagerstroemia indica is smaller than Fructiferous Lagerstroemia indica. The buds of Acarpous Lagerstroemia indica appear vertical and horizontal difference earlier than Fructiferous in the growth process of flower buds,while the bud size have little difference before blossom. The stigma of Acarpous Lagerstroemia can accept the pollen of Fructiferous Lagerstroemia indica, while the anther never crack due to the abnormal anther dehydration process, and the pollen grains are misshapen in period of blossom.(2)The bud differentiation and flowering process of Fructiferous and Acarpous Lagerstroemia indica is similar. Two varieties of Lagerstroemia indica all have inflorescence differentiation on terminal and axillary buds in flower bud differentiation process, and the lower part of inflorescence are earlier than upper. In general, the flower bud differentiation is beginning in May later, completed around June 20, and reaching flowering stage in early July, which can be roughly divided into five stages concluding:early differentiation stage, sepal differentiation phase, petal differentiation stage, stamen and pistil differentiation stage. The meiosis of pollen mother cells of two varieties of Lagerstroemia indica are all Simultaneous Type, The ovules are all anatropous, The embryo sac are all Smartweed Type Embryo.(3)The reasons for fruitless of "Xiang Yun"are referred to its female and male infertility. Male sterility is showed as indehiscent anther and pollen abortion, and indehiscent anther was caused by abnormal anther wall tissue dehydration, the cause of pollen abortion is physiological type, which happens in the later development of microsporogenesis. Female sterile happens after Dyad Period when the tissues surrounding the embryo sac are abnormal, the megaspore mother cell meiosis cannot be completed normally and format embryo sac. The reason for the embryo sac abortion of female sterility is caused by abnormal development of Tapetum.(4) There are obvious differences in flower organ differentiation process of four kinds of endogenous hormone changes beween Fructiferous and Acarpous Lagerstroemia indica, and this differences have some certain influence on the development of flower organs of Lagerstroemia indica. The studies suggest that the higher levels of GA3 and IAA in prophase of flower organ differentiation, the lower level of the ZR content and higher levels of GA3 content in late flower organ differentiation are all adverse to the flower organ development; The phenomenon that the Acarpous Lagerstroemia indica buds appear vertical and horizontal difference earlier is associated with higher level of IAA in prophase of flower organ differentiation; The abnormalities in flower organ differentiation process of endogenous hormone have affected the development of tapetum of acarpous Lagerstroemia indica, and have connection with male and female infertility...