Study On Morphological And Basic Physiological Evolution Of Floral Bud Differentiation In Two Kinds Of Syringa Spp.

Syringa Oblata and Syringa Chinensis Will were used as experiment materials in study. The morphological progress of flower bud differentiation was studied by the method of paraffin section and changes of hormone content, nutrient content and nucleic acid content were analyzed in the floral bud differentiation. It determined the period and process of flower bud differentiation and the relations between hormone, nutrition, nucleic acid and flower bud differentiation of two kinds of Syringa spp. The experiment results were as follows:1. Physiological differentiation stage: physiological differentiation stage of Syringa Oblata was from May to July, about fifty days. Physiological differentiation stage of Syringa Chinensis Will was from June to July.2. The flower bud differentiations of two kinds of Syringa spp. were divided into eight stages,including vegetative phase, initial differentiation phase, involumcrum differentiation phase, inflorescence primordium differentiation phase, sepal differentiation phase, petal differentiation phase, stamen differentiation phase and pistil differentiation phase.3. In the stage of flower bud breeding of Syringa Oblata, the contents of soluble sugar, starch, soluble protein and nucleic acid all accumulated largely. They were decreased in morphological differentiation stage, but increased a little in later flower differentiation. In the stage of flower bud breeding of Syringa Chinensis Will, the contents of soluble sugar, starch, soluble protein and nucleic acid were all accumulated largely.4. The total content of nucleic acid was increased continuously in physiological differentiation stage of flower bud and decreased in early morphological differentiation stage. Metabolism model of nucleic acid was that the trend of RNA was double peaks and DNA was single peak, RNA/DNA was approximate to double peaks. The change trend of nucleic acid content of Syringa Chinensis Will leaf was similar to Syringa Oblata, but its peak was later one week than Syringa Oblata. Metabolism model of nucleic acid was that the trend of RNA was single peak and DNA was double peaks, RNA/DNA was double peaks.5. In the flower bud differentiation of Syringa Oblata and Syringa Chinensis Will, the high contents of ZRs and ABA in flower leaf promoted formation of flower bud. High levels of IAA and GA inhibited flower bud formation. High level of ZRs/IAA was not only helpful to the formation of floral buds, but also benefit for the flower buds morphological development. High levels of ABA/IAA, ABA/GA were helpful to flower buds morphological development.