Unlocking the Flavours of Micro-Dwarf Tomatoes with an Ambitious Crossbreeding Effort
Micro-dwarf tomatoes are a fun and rewarding winter project, but it can be difficult to find varieties that offer the perfect combination of size and flavor. To this end, a group of gardeners have undertaken an ambitious crossbreeding effort to create a tomato small enough to grow indoors yet also with great flavour.
The initial crosses were made between Andrina, Venus, gold pearl, Aztec and full size OP indeterminate tomato plants. The F1âs were grown over summer, and the F2 seedlings sown in autumn. Approximately 25% of those grew into micro-dwarfs. Four different crosses were grown by two gardeners in North Carolina (NC) and one gardener in another location, who graciously offered to participate in the F2 growout.
The micro-dwarf line stabilized after the initial cross managed to produce larger fruit than the original TinyTim variety used. Though not as flavorful as desired, it showed that micro plants could work with genetics for larger fruit. The average fruit size was 20.12 g., some averaging ~25g while others ~15g. There was a strong plant-position-effect in the data, with roughly twice as big as those on happy Tiny Tim plants grown in previous years. One plant had distinctly purple leaves, with no reduction in productivity compared to its neighbors.
The ideal goal is a fancy striped micro that tastes great. My understanding is that these micro-dwarfs have two recessive dwarfing loci, so they'll be 1/16 of the F2s. It's estimated that around 20% of the F2s will stay small, culled from 150 plants down to 45 at present and expected to cull another half of those. Charley is down to 18 small dwarf plants from his original number and his are further ahead beginning to bloom.
Though aiming for fruit smaller than cherry size, beefsteak parents were crossed with the micro in some of them in an effort to bring some flavour into mine. All of them tasted very good and notably far better than the micro parent, giving hope that there may be something good to take forward from this project. Variety in colour, leaf form and potential for stripes is also possible from these crosses so quite a genetic alphabet soup has been created here.
It remains to be seen if this ambitious project will yield results or not - only time will tell! However, it demonstrates how passionate gardeners can come together and collaborate on creative projects like this one in order to achieve something special.
What is the goal of this project?
The goal is to create a new tomato small enough to grow indoors yet with a great flavour.
How many crosses are being grown?
Four different crosses are being grown by myself and friend Teresa Smith in NC, and Salsa Charley also graciously offered to participate in the F2 growout and is growing out some of the Andrina cross.
What size fruit is expected?
The average fruit size in this generation was 20.12 g, roughly twice as big as those on Tiny Tim plants. The ideal goal is a fancy striped micro that tastes great.
How many dwarf plants are expected?
My group has been culled from 150 plants down to 45 at present and expect to cull another half of those. Charley is down to 18 small dwarf plants from his original number and his are further ahead beginning to bloom.
Is there any flexibility in the definition of a micro?
Yes, if the flavour is there, the standard definition of a micro (under 14 inches at maturity) can be stretched to 18 inches for this project.
What other qualities are being looked for?
Selection is also being made for variety in colour, leaf form and potential for stripes. A plant that is attractive, healthy and reasonably early is also desired.