Oxalis tuberosa is an Andean tuber that tuberizes in short days, prefers moderate temperatures and adequate inputs (water, fertility) and is frost intolerant. Its nutritional, taste, cooking and storage (and lets face it aesthetic) qualities make it an interesting crop for development however its goldilocks personality means it grows well in limited regions in North America. I have been participating in several breeding projects to produce more widely adapted varieties from true seed. Some progress has been made in quick to bulk vareities but not sufficient for most potential growers.
Growing for me is not merely about variety + geography. Crops are grown in a cultivation system. If us northerners didn't pre-start tomatoes, we'd probably still get fruit (just ask people with volunteer tomatoes) but we might be disappointed by yields or at least start of fruit set. Planting out sweet potato tubers rather than slipping has lead to crowded growth and significantly lower yield in my experience. Therefore, I'm seeing a potential not only in developing day nuetral crops but also in a selecting for an alternate cropping system for propagation or the plate, especially in adverse years.
In the Ottawa region, even though I protect with floating row cover or even heavier protection depending on the year, I have to harvest in November as the ground freezes shortly thereafter. I therefore, usually pull my plants with intact stems and even foliage, remove large tubers and then store in plastic bags someplace above freezing that is not too dry. I find that any remaining stolons plump up and aerial tubers are produced. This year, I also took stem cuttings for an indoor flowering experiment though I expected that it was likely that I would see mostly just stem to tuber conversion. This is indeed what I saw though in some cases they went from stem to tuber to roots from the tuber to presumedly vegetative growth out of the tuber.
In other cases, I did see some root development off of hte stem though no new vegetative growth (yet). This got me thinking. All stems are potential tubers and stems was one thing I was capable of growing.
Not all of my stored oca readily produce this stem to tuber conversion or at least not in my storage regime. I have not really looked into if there is a correlation to general readiness to produce tubers though infamous Seedling 12 that produced masses of green growth at harvest but zero tubers has finally begun to heavily stem tuberize. Good thing as it sure didn't do the stolonization thing. I was ready to chuck it. Might still do...
Looking at the above plants, you can see the massive potential for propagation material. On the left is a plant that is heavily converting stems to tubers though these would be classified as marbles according to the Guild of Oca Breeders sizing key. On the right, you have stolons that produced tubers or had very small tubers enlarge to a more reasonable size.
Some plants did not do much after harvest in terms of stem->tuber conversion in the near cellar like conditions that they were stored. Seedling 5 on the right was one such though it was a heavy cropper at harvest (comparatively in the Algonquin Student Cultivariable grow out) and its stem cuttings readily tuberized in warmer conditions.
I can see potential in two ways.
The first is that if you are about to lose Oca because of unusual weather or rodent activity but have intact stems and are a small scale enough grower that pulling and storing all your plants doesn't sound too daunting, then this is a potential method to produce propagation material. Alternatively, if you have intact stems and just want more material to share around, you can produce marble or larger sized tubers this way. Note smaller tubers need more care in storage as they are more likely to rot or shrivel up.
Alternate Cropping System
This is more of a pie in the sky idea but I'd like to experiment with it next year. By selecting plants that readily make large tubers in storage, you could develop a system that would work for northern growers. At least until that magical day where we find the day nuetral or super early variety.
All about growing, selecting and using edible plants in the Ottawa valley.