... growing and hybridizing all kinds of plants in zone 6b Maryland since the 1980's.

Thursday, September 1, 2011

Tomato hybrids: 'White Wax' X F4 hirsutum derivative

These are fruit from one of this years hybrid tomato seedlings. It’s a seedling derived from ‘White Wax’ tomato that I grew last year and pollinated by a 'Brandywine' x hirsutum derivative (F4) that showed considerable purple-black pigmentation. Lycopersicon hirsutum (currently reclassified as Solanum habrochaite by taxonomists) is a green-fruited wild South American species. This F4 derivative line had a fairly small fruit with a green-yellow ripe background color and not-so-great flavor. It took after hirsutum much more than 'Brandywine'. My aim was to get the purple-black pigment of this seedling into a larger, better tasting, white background fruit (hence the ‘White Wax’ seed parent in the cross). So far these three fruits represent the best stepping stones in that direction. They are showing at least a little bit of the purple pigment and MUCH better flavor and size. Hopefully the next generation from selfing, will have a few white revertants that also tend toward ‘White Wax’ in size and flavor, while still expressing some of that purple-black pigment. Fertility seems to have improved already too.

The first image shows a slightly unripe fruit, so that you can see that the green shoulders and purple-black speckling are two different traits. [Someone had once insisted to me (without seeing in person) that what I was seeing was just chlorophyll] Often the green shoulders and purple speckling will occur in the same area of the fruit surface, but as the fruit ripens the green will disappear while the purple does not. On this particular fruit shown, the purple and green overlap but not completely. So the brownish blush in the center of the photo is the purple pigment (it looks brownish when overlaying a yellow background) while the green shoulders are on the left.
The second image shows two completely ripe fruits. The purple speckles of pigment on these are facing the camera, all around the glare/shine spots. This purple blush is definitely variable and a lot of the variability seems to be temperature and sunlight dependent, so I'll post pictures of more intensely pigmented fruits later in the season if they appear. I'll also try to get some pictures posted of the F4 hirsutum derivative that fathered this hybrid.

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