MSU/AEC Plant Research Laboratory, Michigan State University, East Lansing.
Planta. 1970 Dec;95(4):330-5. doi: 10.1007/BF00384704.
Germination of the seeds of Phacelia tanacetifolia is inhibited by light. Removal of that part of the covering structures of the seeds which directly covers the radicle allows full germination in light. The rate of O2 uptake in the seeds increases following imbibition, and reaches the same steady rate in light and in darkness after 3 hr. From the 14 th hour on, dark-imbibed seeds show a linear increase in the rate of respiration. This increase is not observed in "dormant" seeds incubated in light. In normal dark germination, protrusion of the radicle begins at 12 th hour following soaking, and by the end of 18 th hour approximately 60% of the seeds have germinated. The seeds which have been scarified at the radicle end and germinate readily in light show a steady increase in Q O 2. If scarified seeds are allowed to imbibe 0.3 M mannitol and are then incubated in light, the embryo does not grow and the pattern of O2 uptake becomes identical with that of intact seeds in light. Mannitol, however, does not inhibit respiration by itself. These observations indicate that the increased O2 uptake is the result rather than the cause of seed germination, and that light does not cause dormancy by inhibiting O2 uptake. Measures effective in releasing dormancy (dark incubation, mechanical scarification, gibberellin treatment) do not induce germination by facilitating oxygen entry.
腺梗繁缕种子的萌发受光照抑制。去除直接覆盖胚根的种皮部分，可使种子在光照下充分萌发。种子吸水后，O2 摄取率增加，在 3 小时后，在光照和黑暗中达到相同的稳定速率。从第 14 小时开始，黑暗吸水的种子的呼吸速率呈线性增加。这种增加在光照下孵育的“休眠”种子中观察不到。在正常的黑暗萌发中，浸泡后 12 小时开始胚根伸出，18 小时结束时，大约 60%的种子已经萌发。在胚根端进行刻痕处理并在光照下容易萌发的种子中，QO2 呈稳定增加。如果允许刻痕种子吸水 0.3 M 甘露醇，然后在光照下孵育，胚不会生长，O2 摄取模式与光照下完整种子的模式相同。然而，甘露醇本身不会抑制呼吸。这些观察结果表明，O2 摄取的增加是种子萌发的结果而不是原因，光照不是通过抑制 O2 摄取来引起休眠。有效的解除休眠措施（黑暗孵育、机械刻痕、赤霉素处理）不会通过促进氧气进入来诱导萌发。
