Most fruit lovers know that of all the fruits out there, apples enjoy the distinction of having the greatest variety. They are the nearly the only fruit or vegetable in the grocery aisle where variety is a major selling point. Apples can taste sweet or tart, be snappy or mushy, hold their shape when cooked or just fall apart. There are literally thousands of varieties of apples, with nearly 100 in common cultivation.
If you were to plant the seeds of an apple, you are very likely to end up with something that is not like the fruit it came from. I recently saw a picture of the actual fruit produced from seedlings that all came from the same tree. The fruit were incredibly diverse ranging in color from gold to red, and from small to large (I couldn’t taste them, but would be willing to bet that the taste was equally inconsistent). So if apples don’t grow reliably from seed, how do apple growers produce a consistent product?
The answer was discovered over a hundred years ago as growers tried to “move” varieties from one place to another. It turns out that apples are very tough plants and they can be grafted easily. The graft is accomplished by taking tender bud wood (called the scion) from the desired plant, and inserting it into a freshly cut slit under the bark of the host apple tree. When done correctly, the cells of the host and scion merge nicely at the graft, and allow the scion to continue growing into an exact replica of its original parent. This is a kind of clonal reproduction that guarantees that there is no change to the variety over time. A variation of this on small nursery trees is called budding, and it is pretty much the only way that apples are propagated today.
If we look back at the apples in common usage 200 years ago, they are typically soft, have thick skins, have rough patches on their skin called russetting, have a very short window for harvest, don’t store well, and generally wouldn’t compete well with today’s varieties in the grocery aisle. But once there was a good solution in place to maintain and exactly propagate a variety, there was a lot of effort put into breeding.
Apple breeding is a very long term process taking anywhere between 15-30 years for results of a cross to be well understood. New varieties usually come about in 3 ways: sexual crossing between existing varieties; volunteer seedlings that are “found”; and genetic mutations of existing apple wood.
Sexual crossing is a slow process because even with parent seeds from the same apple, the “child” trees may yield apples that are very different from each other. Each seed must be grown to a mature tree before only the best trees are kept for future crosses or commercial propagation. For example, the popular variety Honeycrisp was actually bred in the 60’s, so long ago that records of its exact parentage have been lost. Nonetheless, this is the process whereby almost all brand new varieties are grown. It is a slow, expensive process that is leading the industry to some major changes. More about that in my next post.
The second method mentioned is where seedlings trees are identified as being somehow worthy of saving. An example of this is the variety “York” which is still considered an excellent baking and processing apple. It was found growing near York PA nearly 100 years ago, and saved.
The third method is very often used to improve an existing variety. It is pretty common in an orchard to come upon a limb that acts a little differently than the rest of the tree. Its apples may ripen earlier, or they may be redder, or they may taste a little different. These “sports” are often identified by alert growers, and cuttings shipped to nurseries to serve as a cultivar of the parent variety. This can cause a variety to change fairly quickly due to human-selected preferences in a variety.
For example, throughout the second half of the 20th century, Red Delicious was continuously selected for improvements to color and shape, such that the most modern strains are almost always 100% dark red with a pointy shape; unfortunately the selection process also diminished the flavor of America’s favorite apple variety. Gala has also changed: what started as a red blush over a yellow base has now been selected to be another red apple. Fortunately, the taste has remained unchanged.
Future posts will examine the future of apple breeding.