大花杓兰种子形态特征与生活力测定

Morphological characteristics and viability testing of Cypripedium macranthos seed

为建立濒危兰科植物大花杓兰的种子无菌萌发技术体系,该实验通过含水量测定、TTC染色、石蜡切片、无菌萌发等方法,综合研究种子授粉后28d(28DAP)、56DAP和84DAP的未成熟种子和成熟种子(97DAP)的形态和生理活性特征。结果表明:28DAP的种子刚受精,含水量高达92.97%;其他时期的种子均处于球形胚时期,随种胚的发育,含水量从85.32%降至7.70%;28DAP的幼嫩种子在TTC中着色困难,但TTC可以作为球形胚时期成熟种子的生活力指示剂;在相同的无菌培养条件下,56DAP的种子萌发率为31.44%,其余时期的种子均未观察到种子萌发,28DAP的种子过于幼嫩而不能萌发,84DAP和97DAP的种子则是受次生抑制因子的影响。说明大花杓兰无菌萌发的适宜采种时机为种胚已发育至球形胚阶段、次生抑制因子起作用前的时期。

In order to establish in vitro seed germination techniques of Cypripedium macranthos,an endangered orchid species,we investigated morphological characteristics and physiological viability of mature and immature seeds at 28,56,84 and 97 days after pollination（DAP） through water content testing,TTC viability testing,paraffin-section and in vitro germination. The results showed that seeds,collected at 28 DAP,were just fertilized,in which the water content was as high as 92.97%. Seeds collected at other times were all at a stage of global embryo and the water content varied from 85.32% to 7.70%. TTC testing was not able to test seed viability at 28 DAP since the embryo was too young to be stained. Under the same in vitro growing conditions,31.44% of the seeds collected at 56 DAP germinated,while no germination was observed in seeds collected at other times. Seeds collected at 28 DAP were probably too young to germinate and seeds collected at 84 DAP and 97 DAP could be prevented from germinating in vitro by some secondary factors. A suitable collection time for seed germination in vitro would be between the times after the seeds reached their global embryo stage and before secondary control factors started to function.