Sunday, August 5, 2012

Artificial Corn Insemination. Or, Corn Hand-Pollination.

I need to explain something to you. Rather, I need you to understand what summer means for Christy.

Me teaching Corn HP with a co-worker at the latest SSE Conference. Picture taken by SSE photographer, Tim Johnson.
Let's talk corn - specifically, heirloom corn. And growing it in Iowa, a state full of corn. Corn is wind pollinated, which is a problem when corn grows everywhere. Wind pollination means corn pollen will try to get all up in any available corn silks, resulting in the dreaded cross-pollination. So, what does that mean when you need to save seed from heirloom corn? You hand-pollinate it. And since not only is corn wind pollinated, but extremely susceptible to inbreeding depression - you must grow at least 200 individual corn plants per variety. And now we come upon Upper Field North West, where 20 varieties of corn are growing for me to pollinate (and if you've tried out that math, make sure to note we've grown about 300 plants per variety just to be safe, so that's about 6,000 plants).

The first challenge to Corn Hand Pollination is pure survival against deer, raccoons, drought, heat, and thunderstorms. Deer love to eat random parts and tassels, raccoons will tear that shit up regardless of the effort invested on my part, the drought will dry the anthers and stunt the plants, the heat and humidity will challenge anyone attempting to pollinate the corn, and the thunderstorms will blow all that corn over (and even if you attempt to trellis the weak-ass corn, the twine just serves as a handy way to decapitate it!) I haven't even begun to think about crows, fungus, or insects - but I'm told that will come too.

A quick Corn Anatomy lession, thanks to the Plant and Soil Sciences eLibrary. 
If the corns survive (and yes, I say corns - which apparently makes me stand out as a non-midwesterner, but now I'm going with it), then we can begin the actual mating process. First, the emerging silks must be protected from random and prolific in-the-air-and-everywhere corn pollen. Here we use a little wax-lined bag to cover the silks, what I like to call a corn condom (technically, it's called a shoot bag). And if this sounds easy enough, let me clarify the process here. First, one must find emerging shoots before they silk, which in itself is a task. Leaves must be torn off, and one must make sure that the shoot isn't too small, but also not too far gone. Then, the top of the shoot must be trimmed to 'release' those tightly wound silks. The corn condoms must cover this shoot, but one must make sure to slit the leaf a little to ensure the bag stays put and your efforts are not in vain. One must attempt to find two shoots per plant. When silks start showing up, carefully protected in the little corn condoms, then one can begin the next step.

Now pollen must be collected. This involves stapling bigger bags around the tassels of the corn. But not just any tassel will do - oh no. You need an actual shedding tassel, one that's not too spent but one that's not too early. If you find any of these, then you have to staple the bags on in such a way that the wind won't blow them off and the pollen won't fall through. And this must be done as late as possible in the afternoon to ensure the freshest of pollen for morning pollination. If you're preparing to pollinate a variety, you have to go through and double check the shoots and shoot bags, trimming any silks that have gotten too long and releasing silks that may be trapped in shoot leaves. At this point, it helps to mark any bags that are ready.

Come morning time, one must wait for the dew to dry up and for pollen to begin shedding, meaning actual pollination doesn't start until 10am. At this point, tassel bags are carefully collected, all the pollen is consolidated into one bag, and anthers/ants/aphids/etc are filtered out. Hopefully at the end of this, you'll have a bag full of pollen. Now comes the actual pollination part, in which a shoot bag is lifted, pollen is dumped onto it, spread a round a little, and then a used tassel bag is stapled around the shoot and stalk in a specific way that will make sure it doesn't blow off. You have to make sure the silks won't get any other pollen. We also mark each shoot with flagging tape so that if the bags fly off at the end of the season, we'll still know which corn we pollinated.

This all sounds understandable and not that difficult - tedious, but otherwise easy right? Well, there are a few more things to learn. First, corn wants to outbreed - meaning, it really doesn't want to mate with itself. This means it's likely to shed pollen when the shoots aren't ready, or visa versa. And while this may be smart of the plant, you come upon situations in which only 30 of the 300 plants have shoots, but the tassels are at the peak of pollen shedding. So, we have to pollinate just those 30 shoots, and repeat this process until we get as close to 200 as possible. This means we may go through a particular variety 2, 3, or 4 times depending on how asynchronous the pollen-silking is. Which is fun.

What makes it even more fun is that because we're working with heirloom corn, this shit is crazy. Some varieties are only a foot tall, others are incredibly bushy, some have tassel-ears, some need to be cut three inches to release the silks, others will push silks up before you can even see the shoot, and some will just fall over if you look at them wrong. Genetic diversity, at its finest. And with a drought, we have the additional challenge of stunted, short plants ... where several of our varieties are no more than three feet tall. Try pollinating that all day. It's fun. The scarier part of the drought, actually, is the fact that it shortens the window you can pollinate (6-8 days to 2-3), it dries up the silks and pollen quicker, and it forces plants to chose between ears or tassels. Essentially, despite all this hard work, our yield is going to suck.

So, welcome to my summer in Iowa. I do corn all day, and that isn't even enough time. It takes three people 2.5 hours to pollinate just two varieties ... and I have 20 to pollinate. Several times. And just one extra person to help me, maybe two in a week.

We tell a lot of dirty Corn HP jokes.

In the end, Corn Hand Pollination forces me to accept situations as they are, to be at mercy of things outside of my control on an everyday basis, and to work outside during the heat and humidity of Iowa all day. It's building Midwestern character I never thought I'd need. That's a silver lining, isn't it?

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