Hypothesis for the role of natural selection of hardneck and softneck garlic types

The season is progressing, and I wanted to share some speculative insights that I had this season. I’ve been reflecting on how and why softnecks (Artichoke and Silverskin families) are so variable year to year. I have to say it was a mediocre year for them for me. For 2018 most of the blame lies in that I miscalculated the space I needed for garlic, so I had to use unamended ground by the time I got to most of the softnecks on my list. However…before I learned more about pH, and before I’d even grown any softnecks, I used to select my hardneck seed year by year for its ability to still do well in rockier, more acidic (ph 5.2 to 5.4!!) soils. And I could actually eke out halfway decent bulbs. Not county-fair-prize-winners, mind you, but I’d slowly built a stock that could get medium and medium large in such conditions.

Compare this to what you’ll see on websites elsewhere, the simple statement that “softnecks are the largest of all garlics”- which is obviously not the case for the average Northern grower. Something is going on here when there are such incongruent statements and observations. I think, simply, that softnecks are more plastic/flexible in response to rich soils. They will show, quickly and punishingly, if your soil is marginal in either pH or general nutrients and organic matter. Conversely, they will show spectacularly if you’ve got all those things, and adequate moisture. The one year I had softneck monsters was when I planted some of my garlic crop in silt. A rare treat in my area, and certainly a rare soil type on my farm (it’s an 800 square foot anomaly). The hardnecks there did well, but the softnecks even better.

Going to the basics of evolutionary biology (how these garlics fared under varying amounts of human neglect, human imperfection, etc) I’ve come to hypothesize something simple, and I have two pieces of supporting evidence in the structure of the two phenotypes. Softnecks evolved/were selected for in alluvial/silt based agriculture, while hardnecks survived in non alluvial agriculture. Rocks and stones occasionally amended with animal manure or very scarce cover cropping/ green manuring.

*quick reminder, alluvial=flood. Think of the Nile River agriculture of the Egyptians.

My first bit of evidence (anecdotal and not yet qualified) is that I’ve noticed my softneck roots are almost always thinner, and higher in number. This root type only seems to succeed when there is relatively few rocks in the soil, and when the soil is as silty as possible. Small roots for small particle sizes. I have also failed to see softneck roots ever get colonized by mycorrhizal fungi, but that is a reaching hypothesis. The roots may not be suited for it, or perhaps they simply don’t need it since they have more surface area to mass ratio for exploiting phosphorus anyway.

Conversely, hardneck roots almost are the thickness of angel hair pasta or thin rice noodles (noticeably thicker than softneck’s finer roots). I don’t really know the mechanics of how the roots push through soil as they grow, but I have to imagine they have to be thicker and stronger to push through rocky soils. Or perhaps that growth has nothing to do with it but is just a consequence of the plant needing more, stronger anchoring in rocky soils that heave and buckle with significant water to soil ratios messing things up in winter. The poor surface area to mass ratio also could simultaneously necessitate and allow the colonization by mycorrhizae as well. As evolution moves in beautiful accidental lock-step I can imagine that garlic with fat inefficient roots propped up by an enabling symbiotic mycorrhizal relationship would just continue down that path.

So, that’s the root observation. Whether that’s a phenotype that would change with time, or soil nutrients, who knows. I just bought a cheapo home digital microscope so maybe next year I’ll actually quantify the difference in thickness of the roots.

The second observation is of bulbil-forming behavior in the two phenotypes of hardneck and softneck. Now…to immediately answer a question- isn’t the whole idea of a softneck that it doesn’t form bulbils? Well, not in my area, and perhaps not in others. See, my softnecks frequently form bulbils in their pseudostem, even when the plant doesn’t fully “scape out.” This seems like a strange, radical difference but when you do a post-mortem on one of those plants, it’s not as strange as you think. Hardneck plants have a safely large interval between the plant’s signal to send up the central stalk (the proto-scape) and when to actually start to form mature bulbils in the capsule. The stem is safely way above the pseudostem’s apex when the bulbil forming signal goes. That’s why you watch it fully emerge, hang out for a couple weeks, curl, and uncurl, all before bulbils actually start to swell (if you haven’t cut the scape, of course.) On the contrary, with softneck plants, the signal to send a central stalk (only IF and WHEN that anomaly happens, which is like 30-60% of softnecks for me) is VERY QUICKLY followed by the bulbil-swelling signal. The result is that it goes off half-cocked. The bulbil capsule is barely 2-5 inches above the bulb before it happens. The maturation occurs at the core of the pseudostem, resulting in the Frankenbulbils busting out and creating the weird bulge in the plant. It’s a signal gap, or lack of a signal gap, that results in that.

Now, we have described the observed difference, but what could explain the usefulness of either of these features / phenotypes? I have a nebulous but simple one, and it comes down to natural selection and perhaps some human selection. It’s based on my experience in farming, which is that Murphy’s Law is in full force. If there is any way for something to go wrong, it eventually will. Say it’s 500AD and you’re a week away from harvesting your garlic. But some barbarian raiders come and you have to flee to your cousin in the hills for a couple months, and by the time you come home you find the place half-ransacked and most of your crops burnt or stolen. Your garlic patch is weedy, you can’t find the bulbs, and you’re worried more about starving since your grain crop is ruined, so you let it go for a year, figuring on finding the surviving bulbs as they resprout, crowded, in the spring. In an alluvial/silty soil, the most useful feature of a bulbil is that they will be few (true of the numbers of bulbils that form in the pseudostem of a softneck) so that they’ll come back to size quickly, and they’ll be in place. Not washed out by the potentially frequent flooding of your silty soil. A neglected/forgotten bulb, with 4-6 strong bulbils in a stiff but short stem, will still be close to the surface when more silt is washed up in another flood. Even one flood every ten to fifty years could create the genetic bottlenecking needed to shape an alluvial culture’s “selection” of softneck garlic that occasionally has bulbils. I put “selection” in quotes because it’s more like the environment is choosing for you which garlic of yours will make it and which won’t. In a perfect, controlled world we can all grow all types, but disasters winnow the selection quickly, especially for earlier cultures where more people were growing to stay alive as subsistence farmers, not just growing as a hobby.

Going to the flipside, if we view hardneck types as the natural mountain-and-rocky-soil types, what purpose does it serve to make a massive tall scape that nearly bends over if let go? This is like the Egyptian bouncing onion that some gardeners love. It’s a great way to travel quickly if you’re a garlic plant trying to replicate genes. Marginal soils CANNOT AFFORD overcrowding, much more than silty soils. It’s like the marginal soils of the American Northeast, of Scotland, or western Ireland, or a million other hill cultures out there. The land can only support so much, and thus we have emigration. Vermonters settling Iowa. Scots and Irish settling North America. And so a hardneck bulbil must travel far, and quickly, to make its way in the world. The tall arch of the plant, at 5-6 feet tall, even means it could travel uphill and downhill as needed, as global climates shifts from century to century. One windblast could pelt the plant against the hill and put it a couple feet further up and it could migrate to new, uncolonized territory, which I again emphasize, is needed when your soil is marginal. The fundamental physics of square meters of sunlight, cubic inches of rain, and available soil nutrients shape our human behavior, and it shapes the rest of biology as well.

It is also worth noting as a fast aside, that most of the heirloom types that prove to still produce true seed from true flowers, are the wild archetypes from Central Asia. I’ve read some sources that say this has a strong, but not full, correlation with whichever varieties produce strong, sturdy scapes, as the powerplant of flower production. I also read, in one single article (which I’ll have to find and link!) that true garlic seed production improves with altitude. For an amateur botanist like me, who is not trained in this stuff, I was surprised to hear that but then read that that is a very common feature to many plants. I simply assume that barometric pressure or difference in oxygen/carbon dioxide ratios has something to do with that. That’s all to say that a) hardneck garlics have a previously established link with mountainous areas/areas with deeper winters, and b) the role of true flower production in human selection lands squarely in the hands of mountainous human cultures, who could have directed the future of hardnecks based on what worked in their soils.

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