Oca: Early flowering

Last year, I struggled to find oca varieties to cross early in the season.  I had more short-styled varieties than mid-styled.  About a month after flowering began, I had enough different varieties flowering so that I was able to produce a good quantity of seed.
This year, I have a similar problem.  Flowering started a month earlier than last year, but almost all the early flowering varieties were mid-styled.  You can see in the chart below that from June 1st until July 3rd, I had mostly mid-styled varieties.  One long-styled and one short-styled variety did flower during this period, but they produced very few flowers.

This is not a serious problem for me.  Flowering continues all season, so it is just a matter of waiting for more varieties to flower.  As you can see, by the 13th of July, I had plenty of compatible varieties to work with and, ten days later, I’m almost to the point of having more flowers than I have time to work with.

But, looking at the bigger picture, if we’re going to make oca a more common crop in the US, we need a larger breeding effort.  Unfortunately, most of the country has a climate that is not conducive to flowering – at least in the summer.  Although oca may survive warm summers, it generally doesn’t flower in warm weather.  In most of the US where summers are mild, freezing weather often comes too early for oca.  Four apparent goals arise from these facts:

1. Make oca produce tubers earlier to beat the frost.

2. Make oca more resistant to frost so that it can stay in the field longer.

3. Make oca more resistant to heat so that it will flower in the summer.

4. Make oca flower earlier so that breeding work can be done during milder spring weather.

There are many people trying for goal #1.  I have no idea how much work this will require.  An early oca might pop up among this year’s seedlings or it might take years of small, incremental adjustments to oca’s day length sensitivity.

Goal #2 could have a lot of payoffs, but increasing cold weather resistance is a notoriously difficult breeding goal.  Despite the fact that oca is grown under conditions that flirt with freezing and that it would undoubtedly have been valuable to be able to grow it at higher elevations in the Andes, most varieties are not particularly frost resistant.  But, if the plant could hold longer in the field, that might give growers in hot summer climates and opportunity to collect seed during fall and to begin breeding better adapted varieties for their conditions.

Goal #3 is difficult to assess.  It doesn’t get hot here.  I can’t test for differences in heat tolerance and instead rely on what other growers report.  This may require the next goal to be completed first.

Goal #4 seems like it might be the best approach.  Early flowering would provide the opportunity to catch milder weather in the spring without the threat of frost.  Mature seed is produced in three to four weeks, so could be obtained by the beginning of July.  This might be enough of a window to do some oca breeding in climates where oca doesn’t normally flower in the summer and early fall due to high temperatures and/or low humidity.

My experience shows that some varieties already flower early enough for this purpose.  That’s good news; traits that already exist obviously take less work to breed into new varieties.  Unfortunately, most of the oca that flowered in June was mid-styled.  Mid-styled varieties can cross-pollinate (and self-pollinate) but the odds of success aren’t that great.  Ideally, we need several varieties each of at least two of the flower morphs.  They haven’t turned up this year, but maybe next year.  A combination of varieties with different flower morphs that begin to flower in early June (or even May if we’re feeling ambitious) could provide an opportunity for expanding oca breeding out of ideal climates.

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