Nature of Seed Dormancy in Phacelia tanacetifolia

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Science  23 Sep 1966:
Vol. 153, Issue 3743, pp. 1537-1539
DOI: 10.1126/science.153.3743.1537


The inhibiting effect of light on germination of Phacelia tanacetifolia seed is overcome by removing the tip of the endosperm; however, immersion in solutions of high osmotic pressure reinstates the light sensitivity. Inhibition of germination by high temperature behaves similarly. Dormancy is ascribed to balance between mechanical constraint by the endosperm and "expansive force" of the embryo.