温度、光照和盐分对外来植物黄顶菊种子萌发的影响

Influence of Light,Temperature and Salinity on Seed Germination of Flaveria bidentis(Compositae),a New Exotic Plant

对黄顶菊(Flaveria bidentis)种子的表面形态进行了扫描电镜观察,并从温度、光照、NaCl胁迫及浸种等方面对黄顶菊种子萌发特性进行了探讨。结果表明:黄顶菊种子喜高温,35℃下种子萌发迅速,且发芽率、发芽指数及活力指数最高;光照对种子发芽率影响不大,但随光照时间延长,种子发芽高峰推迟且峰值下降,发芽指数和活力指数逐渐下降;随NaCl浓度升高,种子发芽高峰推迟且峰值变小,发芽率也呈下降趋势,但低NaCl浓度(0.01mol/L和0.05mol/L)胁迫下种子发芽率仍保持在90%以上,且促进了种子发芽指数及活力指数提高及胚根的伸长,结合天津地区黄顶菊生境中土壤的含盐量的分析表明,黄顶菊具有相当强的耐盐性;浸种对种子发芽率和发芽指数影响也很大。因此,黄顶菊成为潜在入侵种与其种子极高的萌发率及耐受高温和盐碱等特性密切相关。

Flaveria biderais, an annual weed of Flaveria （Compositae）, had been newly discovered in China. It might be a potential invasive plant in that of its very strong reproductive and survival abilities. Morphology and surface character of the seed were measured, and seed germination characteristics of this exotic species were examined from temperature, light, salinity to seed soaking aspects. The results showed that ： the seed of F. biderais were adapted well to high temperature and germinated rapidly at 35℃. Its germination percentage, germination index and vigor index were increased with the temperature rose. The germination percentage was affected little by light, while germination peak was delayed, and germination and vigor indexes of the seed were reduced with the prolonged light time. Salinity stress had significant effect on seed germination of F. biderais ： the germination percentage and peak decreased gradually with the increasing of NaCl concentration, while the germination and vigor indexes of the seed were higher than those of the control under 0.01 mol/L and 0.05 mol/ L NaCl stress. Lower NaCI stress promoted the elongation of the radicle. Seed soaking also had notable impact on seed germination. In all, it was suggested that, the extremely high germinability and preference to salinity of the seeds of Flaveria biderais could be closely related with its strong invasiveness.