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Blog, ulluco (Ullucus tuberosus)
Ulluco: Seedling Blast
The last ten days have been a remarkable run for our ulluco project. Seven new seedlings have emerged in that time, bringing the total for the year to 17, a 1.62% germination rate. So far, 14 seedlings remain alive and 6 of those are well-developed, adult plants that will almost certainly set a tuber crop this year.
Measured against the only available comparison, we’re doing well. Lempiainen (1989) reported total germination of 2.04% from 1177 seeds in 1989 at the University of Turku, but they only obtained five seedlings from the seeds that germinated.
So, what is responsible for the current flush of seedlings? We have had a very tough weather year, warmer than usual and pretty dry. In the past two weeks, the weather has changed back to our more typical summer pattern with cooler temperatures, some rain, and daily fog. Daily temperature range has been about 50 to 65F, humidity above 90%, and we’re accumulating about 0.05 in of precipitation per day from fog. These conditions may be part of the recipe for ulluco germination. It is also possible that warm stratification, as we have naturally experienced over the past six months, might play a role. Potato seed germination is significantly greater after about 6 months at 70F and ulluco comes from the same climate. The Turku experiments found the greatest germination between 12 and 24 months after sowing, so it is also possible that we have just entered a more active germination period. The seeds were sowed last October, so it has been almost a year.
Whatever the reasons, it is very exciting to have almost doubled the number of seedlings in the past two weeks. Unfortunately, it is not the ideal time of year to be starting new ulluco plants, but hopefully we can keep everything alive in the greenhouse through the winter.
1) Are these seeds recalcitrant, i.e. will they be killed if allowed to dry out or stored?
2) Do you surface-sow them, or cover them with soil to germinate them?
I’m in CT zone 6b, and planted some, which I will keep watered, and also shaded ~30%-50%, especially when our warmer weather kicks in.
I’ll also be growing some in containers indoors under LED’s. This could be favorable because the lights are cool and easily regulated, humidity can easily be kept high, and the overall temperature range should be similar to the Bolivian environment.
Do you know what viruses these tubers carry, and should I be concerned that my other plants could become infected? This would be a major consideration, because of some of the rare species I grow that I can’t afford to lose.
Thanks,
Rick Buell
New London, CT
RRedBBeard@yahoo.com
Hi Rick. Ulluco seeds are orthodox. I cover seed with about 1/8 inch of fine soil. That said, it is rare to start ulluco from seed. Normally, they are started from tubers, like potatoes. We have offered a little bit of ulluco seed the past few years, but it is extremely hard to produce.
Ulluco can carry many viruses, some of which are cross infectious with potato. See here: https://www.cultivariable.com/andean-roots-tubers/how-to-grow-ulluco/#disease
While I can’t certify that our tubers are completely disease free, we start them every third year from clean tissue culture, so they are probably about as clean as you can find.
Indoor growing will work find as long as you can keep the temperature down. Ulluco really doesn’t like temperatures above about 70 degrees.