As a Whatcom County potato royal, assuming agnatic primogeniture, I was naturally interested in a recent feature in Science on worldwide potato production. Potatoes have become more important for the last decade, especially in India and China.
My father and grandfather raised potatoes for sale directly to grocery stores. Now, only seed potatoes are grown commercially in Whatcom County. Raising seed potatoes is more exacting than raising potatoes for food. Heroic efforts are required to ensure that the seed runs true to type. For example, seed potatoes must be rotated with other crops to ensure that strains don’t intermingle. Sustaining an acre of seed potatoes requires control of several acres of land that can be rotated through other crops like hay and corn.
In the 1960s, world food production soared in what was called the Green Revolution, much different than today’s Green New Deal. The Green Revolution was the result of newly developed strains of cereal grains, mostly wheat and rice, with higher yields, shorter growing seasons, and greater disease resistance. Coupled with modern fertilizers, pest and herbicides, and mechanized farming, world food supplies in increased rapidly and health improved. The current rise in prosperity in India and China is partially due to the Green Revolution which preceded the current computer technology revolution.
Potatoes did not play a large role in the Green Revolution due to a peculiarity in the genetic mechanism of potatoes, which is different from most species. Compare potatoes to humans. Except for sperm and egg cells, each human cell has two sets of identical chromosomes. Sex is all about recombining chromosomes from a sperm and egg into a new double set. Sometimes children inherit the best traits from each of their parents. But they can also inherit the worst of each. Most of the time the combination is a mix of good and bad. In the long scheme of things, this continual mixing produces a variety of offspring that are able to thrive in a wide variety of challenging environments.
Potatoes are different. They can have as many as six copies of each chromosome. When potatoes pollenate and produce seeds (potato sex), the potential variation is huge because there are so many moving parts that can be fitted together in so many ways. More variation means more chances for beneficial varieties. But the combinations are random. Some are good, some are bad.
In the long term, bad combinations that fail to thrive, die and disappear. But in the short term, you have failing plants. Farmers don’t want to waste time and effort growing failures. This is why potatoes are not grown from seed: the farmers never know what they will get from a potato seed. Therefore, potatoes are propagated from pieces of the potato tuber (the part you eat) instead of seed. Without the tingle of sex, the resulting plants are identical to their parents. After all, no one grows spuds for the excitement.
But propagation by cuttings has problems. Seeds are miracles of packaging. Kept dry, a sack of seeds (like wheat or rice kernels) is good for several years without special handling. Add warmth, water, and nutrients, and plants spring up. A single pound of wheat seeds can yield twelve thousand wheat plants. A pound of seed potatoes will yield around ten potato plants. Not only do you need more pounds of seed potatoes than pounds wheat seed for a crop, seed potatoes have to be kept from freezing and they can’t be kept over very easily for a second season.
In addition, developing new strains of potatoes is more difficult than creating new strains of cereal crops. Potato variations may be plentiful but getting a promising potato to breed true is often difficult and time consuming.
If they are so much trouble, why bother with potatoes as a food crop? The answer is simple: my grandpa could get more potatoes with less effort from his land than he could wheat or oats. And he could sell potatoes directly to grocery stores instead of selling it a milling company that would take their share of the profits from the finished product. That meant more profit for him.
My grandpa only raised wheat and oats for his cattle. He could feed them grain directly or take it to the feed mill in Ferndale to have it ground to make it more palatable and nutritious for the cattle , but he never sold grain to a middle man.
Potatoes are good human food directly from the ground. Although potatoes have less protein than wheat, potato protein is more usable for humans. A person eating only potatoes will live longer and be healthier than a person eating only wheat bread. We all know that a diet from a variety of sources is best, but not everyone in the world can make the choices that are effortless for most Americans.
Oddly, the Irish potato famine, which caused the 19th century wave of Irish immigration to the US, was the result of a disastrous combination of potato characteristics: potatoes grew easily in Ireland and the population increased on a sustaining diet consisting mostly of potatoes. Unfortunately, all the potatoes in Ireland were genetically identical due to propagation by cuttings. When a disease, the blight, hit, the entire potato harvest was affected for several consecutive years and the people starved.
Today, post Green Revolution techniques have made potatoes an important new crop. Propagating potatoes by seed has become feasible, and other techniques have developed new varieties that are more productive and support two potato crops per year in some climates. My grandpa’s crop is becoming more important for world nutrition for the same reasons he became potato king: a high yield and a healthy product that is palatable without further processing.