Hybrid FruitsBy Dennis Linden
Growers have been using selective breeding for at least a couple of centuries to increase yields and develop other desirable traits in their productions
Since plumcots are one of the key ingredients in this month’s Guest Chef’s recipe, I set out to write a companion article explaining the differences between plums, plumcots and pluots. However, in the process of researching those distinctions, I immediately bumped into the word hybrid. It’s a word that I have used for years during my produce career without really giving it much thought or, admittedly, knowing exactly what the horticultural definition of the word really meant. So one question led to a second, and some fascinating answers.
First answer: A Plumcot is a hybrid cross of a plum and apricot. A true Plumcot has equal heritage (50:50) of both the plum and the apricot. The fruit is plum-shaped with a smooth, dark red skin; the interior fruit also has a plum texture with a slightly spicy-tart plum-apricot flavor. The Pluot is much sweeter, being more like 75% plum and 25% apricot, with a unique, speckled skin. Conversely, the Aprium is 75% apricot to 25% plum and much sweeter than either of its parents. Apriums have a strong apricot flavor with plum undertones. As one would expect, this fruit’s skin has a slight fuzz and looks like a rose-colored apricot.
I am sure that the mere mention of “crossing breeding” and “hybrid” raises a red GMO flag to some readers. So let’s first clear that flagpole; hybrid fruits should not be confused with the new science of genetically modified crops (a.k.a. GMO). Growers have been using selective breeding for at least a couple of centuries to increase yields and develop other desirable traits in their productions. In fact, I would venture to say that every fruit and vegetable in the marketplace today has gone through a human-induced evolution of characteristics that has helped them all compete successfully at retail with improved color, shelf-life and flavor. However there are some pretty huge differences between the techniques farmers have traditionally used to tinker with the genome of their productions over time versus the high-tech practices that go into producing the four GMO crops in the marketplace today, namely -- corn, cotton, soy, and canola.
Natural cross-breeding is a painstaking process that takes multiple seasons, counted in years and oftentimes decades, to get the desired result. Famed plant breeder Luther Burbank, father of the common Burbank Russet Potato that dominates retail potato sales, was the first person to successfully cross plums with apricots in the late 19th century. After several years of meticulous cross pollination, he came up with a half-plum/half-apricot “hybrid” that he coined the Plumcot. In the 1970s biologist Floyd Zaiger used Burbank’s notes to continue the process. It took him another 20 years to achieve a 75:25 plum-apricot mix that he introduced to the marketplace as the Pluot – and even patented the Pluot.
So what was this guy doing for 20 years? Basically, he was playing the role of the bee by hand brushing pollen from the male flower of an apricot tree to the stigma of the female flower of a plum tree (or vice-versa) to control results. Those hand-pollenated blossoms would produce fruit whose seeds were then harvested, planted, nurtured and some selected for a repeat of the hand-pollination protocol based on fruit characteristics. When this next generation of selected trees bloomed, the process was repeated.
To avoid turning this article into a horticultural how-to manual, I have left out a lot of technical and weather-related hurdles that are a part of this process. Suffice it to say that the Plumcot and Pluot are the product of dozens of generations of crossing plums, apricots, and other plum-apricot hybrids to get just the right combination of flavors and textures. Also this cross-pollination was done between two of the same species i.e. plums and apricots are both stone fruits, hence the “natural” aspect of this procedure. Mr. Burbank did not try to come up with a potato that tasted like a plum, for instance.
Organic Gala ApplesAnother way that we humans naturally engineer a crop is the common practice of orchardists called grafting. The fact is that apple seeds taken from a Gala, for instance, will not necessarily produce another Gala tree. In fact, the DNA may differ significantly from the fruit of the parent tree! To guarantee that a Gala apple will produce new generations of Gala apples, leaf buds are collected from an existing tree in winter and inserted into the root system of another tree in spring just as the tree begins to blossom. The root section of the tree provides the buds with a nutrient system. Trees will produce fruit after a few growing seasons. Again, this manipulation is done between fruits of the same species. No grafting bananas to a Red Delicious apple tree…though that would sure improve that apple variety’s flavor tremendously!
A genetically modified crop is what it sounds like it – a plant, animal or microorganism that is genetically altered using molecular genetics techniques. Corn that has the pesticide Bacillus thuringiensis (trade name “Bt”) engineered into its genetic makeup to make it resistant to certain pests would be a good example of a GMO crop. Bt is a natural pesticide, even allowed on organic crops, but it would never naturally find its way into corn seed. Placing the gene of a cold water fish into cotton seeds to make the crop more resistant to frost and cold temperatures might or might not be a good idea, but it definitely mixes species. The result is GMO cotton and not hybrid cotton. Here are some hybrids that we enjoy every day
Boysenberry (Blackberry-Loganberry-Raspberry), Limequat (Lime-Kumquat), Grapefruit (Pomelo-Sweet Orange), Loganberry (Blackberry-Red Raspberry), Meyer Lemon (Lemon-Mandarin or Orange), Tangelo (Tangerine-Grapefruit). Just to name a few and, by the way, not a Plum-Potato or Banana-Orange on that list; though I am sure someone is working on both!