Friday, April 16, 2010

Didja Know: Apple Tree Propagation


Today's Didja Know came to my attention while watching a Netflix documentary called "The Botany of Desire" by Michael Pollan. Did you know that if you have a wonderful apple tree that produces spectacular quality of fruit, taking a seed from an apple that has grown on the tree would be highly improbable to grow a new tree with edible fruit? That's because the seeds for apple trees contain the genetic code for many possibilities of tree characteristics and any number of the characteristics can develop when the seed sprouts and grows. It's due to a property called extreme hetrozygosity in which something called the alleles of each gene of the seed can be radically different from each other. With an apple seed, each potential variation affects any number of qualities in an apple, including the color of the skin, the size of the fruit, the sweetness of the fruit, disease susceptibility, etc.

Humans, for what it's worth, also exhibit hetrozygosity in reproduction, but it's not nearly as extreme as what you find with apples. Family members may look different from each other, but frequently share familiar features.

Anyway, with regard to apples, the preferred method of propagating a quality apple tree is by grafting. A bud is taken from a desirable tree and grafted onto a young developing tree, which results in an exact copy of the original. Grafting takes all the guess work and thousands of possible variations out of the equation and provides predictable results.

That's not to say it's bad for there to be apple trees grown from seed. Having trees grown from seed allows for biodiversity which creates opportunities to explore more characteristics and cultivate new varieties of trees better suited for various environments, better disease resistance, and preferred flavors. We need to have biodiversity because if we only have limited varieties, over time those varieties become more and more susceptible to disease and pests. It's just important to know that those new cultivars are not easily developed from seeds.

Another contribution from seed-grown apples over the centuries has been its use in creating hard cider, where even bitter tasting fruit could become useful after pressing, storing and fermenting it to create an alcoholic beverage. In fact, according to the Michael Pollan documentary, before 1900, 99% of apples were consumed in beverage form. It wasn't until after 1900 that apples were cultivated to the varieties that we so commonly consume in their natural form. Interesting huh?

So now you know...plant an apple seed for fun, but don't expect edible fruit if you do. For home grown apples, you'll want to seek out a sapling that has been grafted from an already proven tree that has demonstrated the ability to grow well in your area.

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