Serendipity and science. They're the two basic means by which a new apple variety can be developed. Most varieties simply happen—a magical meeting of flower and pollen. Scientists call this a "chance seeding," meaning a tree grows by chance from an apple seed. Scientific breeding, on the other hand, offers a much more controlled way of creating new apple varieties. In both cases, the seed is a cross between the female parent (the flower/fruit from the tree that the apple came from) and the male parent (the variety that produced the pollen).
How does it play out in real life? Consider the following chance seedling: A Red Delicious tree is pollinated by pollen from a nearby Jonathan tree. Although it yields a Red Delicious apple, the seeds in the fruit are a cross of the two parent varieties (Red Delicious and Jonathan). If you planted one of the seeds from that apple, it would grow into a tree that would yield a new, unique variety, one that contains some characteristics of both parent varieties. Like children, each new tree would have a completely unique, individual mix of characteristics from the parent seeds.
Chance seedlings are usually found growing in unusual places, such as fence rows or barnyards. Since the origin of the parent blossoms are unknown (someone could have thrown an apple core anywhere) we can only guess what the parentage of a new chance variety may be.
When scientists get involved, the same principles apply. Only they make sure an apple's ancestry can be traced.
With scientific breeding, pollen from one variety pollinates another variety: only here, a scientist controls the activity. Whether in a field or a greenhouse, the scientist covers the apple blossoms with a fabric or netting to prevent random pollination. When the blossoms open and are ready to be pollinated, the scientist manually applies pollen from the blossom of a known variety. The blossom is covered again.
After the fruit is harvested from the hand-pollinated fruits, the seeds are collected, then planted.
The Growing Process
Here is where apple breeding is a long-term, large-scale project. Blossoms are pollinated in the spring and the fruit harvested in the fall. The next year, the seeds are then planted and it takes four to eight years before the trees, started from seed, yield fruit to be evaluated. Hundreds or thousands of seeds can be planted in hopes of yielding one desirable variety.
Once the trees begin to bear fruit, someone walks the rows of trees and looks for apples that are appealing in appearance as well as taste. And this is only the beginning. Following are many more years of trials to test the variety for weaknesses, such as susceptibility to diseases, insect damage and frost hardiness, as well as desirable tree form and climate adaptability.
Needless to say, fruit breeding is a rare science. A plant breeder is unlikely to become famous during his lifetime, since years must pass before a successful variety becomes popular and adopted for wide-scale planting.
Which brings us to an interesting question: If every apple seed in every apple is a new, unique variety, how do we get orchards full of trees bearing the same variety?
It isn't easy. Once a desirable variety is bred or discovered, branches from the tree are "budded" to a size-controlling rootstock (an apple tree growing on its own roots will stand 30–40 feet high, so growers and their workers prefer the dwarf trees, which are more productive per acre). "Bud-wood," or branches with several buds, are collected from the desirable tree. Buds are areas that sprout in the spring to form new branches and blossoms. The buds are carefully cut from the branches and inserted into a rootstock, which has already been planted in a nursery field. The bud heals into the rootstock and eventually sprouts a branch, which will become the young tree.
The budding of fruit trees requires very precise and technical skills. Nurseries must grow the rootstocks and also maintain blocks of trees to be used for bud-wood.
Obviously, chance seedling is the easier path to a new variety. But scientific breeding allows us to reproduce our favorite varieties. And for everyone who loves the anticipation of biting into a delicious apple, we tip our hats to plant breeders everywhere.