Viviparous5 (vp5) has been located in the short arm of chro­mosome 1 by means of a test with translocation B‑1b. This viviparous shows pale endosperm color, premature germination and albino seedlings. A heterozygous vp5 plant pollinated by TB‑1b pollen gave some pale endosperm seeds which became dormant (deficient endosperm and hyper­ploid embryo), and also normal yellow endosperm seeds which germinated prematurely (hyperploid endosperm and deficient embryo). In addition to placing the gene in the short arm of chromosome 1, these data show that dormancy is in this case determined by the embryo itself, not by the composition of the endosperm.


D. S. Robertson