依据显微结构及光合特性探讨蝴蝶兰花芽分化的时期

以蝴蝶兰‘大辣椒’为试验材料,对花芽分化进程及期间光合特性和碳水化合物、可溶性蛋白及激素含量的变化进行研究。结果表明:花芽长度为0、2、4、8、16和24 cm时,分别处于花芽分化初始期、花序原基分化期、花原基分化期、萼片原基分化期和花瓣原基分化期(16和24 cm)。蝴蝶兰叶片的净CO₂吸收速率在花芽发育前期(0～4 cm)没有显著变化,花芽8 cm时显著降低。花芽中的碳水化合物和可溶性蛋白的含量显著高于叶片,碳水化合物在花芽长度为4 cm时达到稳定水平,可溶性蛋白含量在花芽8 cm时达到叶片与花芽的平衡;赤霉素(GA)的含量在花芽2 cm时达到最大值,生长素(IAA)含量在花芽4 cm时显著升高,玉米素(ZT)含量在花芽8 cm时显著降低,而ABA含量在花芽发育的过程中并没有显著变化。由此可知,当蝴蝶兰花芽开始分化萼片原基(8cm)时,光合生理及生化物质基本达到一个相对稳定的水平,此阶段的蝴蝶兰花芽已彻底完成成花分化。

Explore the Key Period of Floral Determination Based on the Microstructure and Photosynthetic Characteristics in Phalaenopsis

The processes of flower bud differentiation and the changes of photosynthetic characteristics，carbohydrates，soluble proteins and hormones were studied during flower bud development in Phalaenopsis‘Big Chili’. The results showed that flower bud differentiation could be divided into initial differentiation stage，inflorescence primordium differentiation stage，flower primordium differentiation stage，sepal primordium differentiation stage and petal primordium differentiation stage（16 cm and 24 cm），when the length of spike was 0，2，4，8，16 and 24 cm，respectively. The net CO2 uptake rate of Phalaenopsis showed no significant difference in the early stage of flower bud differentiation（0–4 cm），while the rate was markedly reduced in the spike at 8 cm in length. The contents of carbohydrates and soluble proteins in flower buds were significantly higher than those in leaves. The carbohydrate level reached a steady state when the length of flower bud was 4 cm and the contents of soluble proteins achieved a balance between leaves and flower buds when the flower bud grew to 8 cm. The contents of GA in the flower bud reached the maximum level in the inflorescence primordium differentiation stage（2 cm）. IAA levels increased significantly when the flower bud grew to 4 cm，and ZT contents strongly decreased in the flower bud at 8 cm in length，while the contents of ABA showed no significant change during the whole process of flower bud differentiation. In conclusion，the photosynthetic，physiological and biochemical characteristics reached a relatively stable level when the sepal primordium began to differentiate（8 cm），and floral determination was likely to have been completely finished at this stage.