I agree, Maf, it's very confusing and difficult to find 'really' semi-determinate (or even determinate, sometimes!) plants based on the casual discussion or even seed catalogue descriptions... a clear definition is refreshing. Still there are environmental effects on gene expression, which make it even more difficult to differentiate determinate and semi-det in the field. There is really a continuum within the determinate group as well, as to the height and number of branches before forming a terminal bud...
This is from the article Chris linked about 97L97 in the colour genetics thread:
"Line 97L97
tended to be semideterminate under Califor-
nia growing conditions. (Plants with delayed
termination of the main stem, thus more in-
florescences, are termed semideterminate.)
Semideterminate growth habit is controlled
by a recessive gene, sdt, and may not be
expressed under some environmental condi-
tions (Elkind et al., 1991). Genetic variation
in the number of inflorescences on the main
shoot may also occur in determinate geno-
types, however, resulting from the timing of
formation of the final two inflorescences
(Cuartero and Cubero, 1985). Additional
analysis is required to distinguish between
these genotypes in 97L97."
The tomato parent of 97L97 is Floradade, described elsewhere as a 'large determinate' and 4-6 ft tall... sounds semideterminate. Unfortunately it's a hot weather variety, not so useful for climates like yours and mine. Zolotoe Serdtse is the one I've grown and believe to be semi-determinate... but I'll have to do some counting to confirm this by the definition given.
|