Studies On Flower Bud Morphodifferentiation And Adaptability Of Introduced Lagerstroemia Indica Cv. In Wuhan

Lagerstroemia indica cv.is an important woody flower blooming in the Summer and bears many excellent characters such as blooming earlier, long bloom duration, strong pollution resistance, so it is used a lot in the construction of landscape now.In this study, the paraffin cut method was used to observe the flower morphogenesis of Lagerstroemia indica cv., and comparation with the three native species in open field cultivation was carried to evalute the adapbility of Lagerstroemia indica cv. in Wuhan.The results were presented as following:1. The flower bud differentiation stage and flowering period of Lagerstroemia indica cv. are in the same year. The flower bud differentiation process lasted for about 30 days from inflorescence primordium differentiation stage in late April to carpel primordium formation in late May .The process could be divided into 8 phases: before differentiation, initial differentiation phase, inflorescence promordium phase, single flower primordial differentiation phase, sepal differentiaton phase, petal differentiation phase, stamen differentiation phase and pistil differentiation phase. The phase of carpel differentiation and pistil differentiation were were relatively short, only about 3-5 days, and the phase from inflorescence primordium differentiation to sepal differentiation is relatively long. The differentiation of single flower and inflorescence is centripetal and from the inner to the outer respectively.2. The gynoecium was composed of 4-6 compound carpels, the ovary is 4- 6 loculed and has 6 or 7 anatropus ovules in each locule. The ovules were double integumentary and crassinucellate. The magaspore mother cells undergo meiotic divisions and develop into a linear tetradas of megaspores. The chalazal megaspores are functional one, which develops into a polygonum type of embryo sac. The two polar nuclei fused into a secondary nucleus before fertilization.3. The anther was four-sporangiate, six - sporangiate was seen occasionally. The development of anther walls conforms to the basic type, which were composed of four layers: epidemis, fibrous endothelium, middle layer and tapetum respectively. The tapetum is degraded soon after the microspore mother cell was formed and the development of the anther wall with 2-nucleate cells is of the glandular type. Cytokinesis of microspore mother cell in meiosis was successive type and the microspore tetrads were tetrahedral. Tetrad cells and microspores are irregularly shaped during the microsporogenesis. The mature pollen grains were 3-celled.4.Compared with the three native species L. indica, L. indica var. rubra and L. indica...