I expect that this goes along with the question that:
when we select for one trait, are we also selecting for other traits?
DELAY OF GERMINATION regulates both seed dormancy and flowering time
See:
Henry,
Yes! Even when we don’t notice.
Back in the mid-19th century, Donald Beaton commented that geraniums (Pelargonium spp.) imported from South Africa survived the English winter. But the highly improved florist varieties, selected for larger, brighter blooms, died during the winter. Selection for some traits allowed other, undesirable traits to become expressed.
http://bulbnrose.x10.mx/Heredity/Transilience.html
Karl
This is more of a conundrum than simply being due to linkage. Germination timing IS flowering timing, they cannot be separated (imho). The implication is that optimal flowering period correlates with optimal germination time. From a breeder’s perspective this means that hybrids can and should be finely tuned to their environment - one size does not fit all.
This actually makes life easier because it frees us, as amateurs, to focus on developing hybrids for our own environment. It makes life more difficult for commercial breeders because they have to serve many markets.
DELAY OF GERMINATION regulates both seed dormancy and flowering time
Don,
This may be true in some habitats, but certainly not in all.
In some places, late germination protects seedlings from warm spells in Winter and late frosts in Spring. But rapid growth and early maturity may allow some plants to take advantage of Spring rain, while finishing their business before the onset of Summer heat and drought. Other species may tough-out the dry period, waiting for the late summer rain. Thus, late germination would work for both early and late flowering, in different species.
To the contrary, where winters are reliably cold and late frosts are uncommon, deep dormancy is not so critical. Bloom time, on the other hand, would be subject for selection to later conditions.
I’m reminded of Michurin’s observation:
Already in the 1900’s, while working on hybrid varieties of yellow cigarette tobacco, the Kommunarka early-ripening melon and hardy grape seedlings—the first to be produced in those days—I was agreeably surprised, when selecting seedlings that completed their vegetative development earlier than others, to find that some of the seedlings that had germinated from seed later than others, namely, at about the beginning of July, managed to complete their growth and mature even earlier than those that had germinated in the middle or beginning of May.
I made a note of this marked, and at the same time rather paradoxical, phenomenon, and in subsequent years I never failed to keep watch for similar manifestations in interspecific hybrids of other plants. It turned out that this phenomenon is in most cases to be met with in hybrids from parents whose habitats were very far apart, and that, on the contrary, it is practically never encountered in simple seedlings or in hybrids from varieties of one and the same species coming from mutually close places of origin.
In these cases, timing of germination and timing of flowering were not linked in the same way as described in the report Henry linked. Early germination was sometimes associated with late maturity, late germination with early maturity.
Karl