White 1015Y Texas Sweet Onions ("Contessa")
Reading the history of Texas sweet onions is a bit like reading the Book of Genesis. If you substitute "Dr. Henry Jones" for "God" and "1944" for "In the beginning" both stories proceed with a long list of "who begat who" that stretches longer than the average reader's interest or memory. In the case of Genesis we can assume that that all the "begetting" was accomplished by the human-on-human pastime known as "whoopee." The same however cannot be said for the creation of Texas sweet onions. Herein lies a tale of an unusual quirk of onion biology and lots of smarts on the part of plant geneticists such as Dr. Henry Jones.
The "In the beginning" line for Texas sweet onions opens in the late 1800s when Texas farmers discovered that their climate and soils could grow Spanish short-day onions that tasted "sweet." Sweet onions are usually not "sweet" in the conventional sense of having more sugar than other onions but they do have lower concentrations of pyruvic acid which gives an onion its pungent taste. Thus a "sweet onion" tastes mild, less pungent. Texas "sweet onions" were a hit nationwide and business was good. But farmers grew impatient with the variable yields and sizes of onions from the same batch of seed. They wanted bigger onions with more uniform growth.
From a plant geneticist's point of view the wish list for a better sweet onion was feasible. Size, 'sweetness', color and maturation time are characteristics that are more or less under genetic control. If strains of sweet onions with one or more desirable characteristics could be crossed the resulting offspring might have more good things than either parent. Moreover the first generation offspring of two genetically non-identical plants are are often more vigorous and productive in a general way, a phenomena called 'hybrid vigor.' But the problem was that no one knew how to make a hybrid onion.
The discovery of how to make a hybrid onion belongs to Dr. Henry Jones and his research group at the USDA. It was a tour de force of observation, experimentation and hard work. The technique is difficult to describe in a nontechnical manner but essentially Jones found a way to reverse the overwhelming odds that an onion flower will pollenate itself. Onion flowers contain hundreds of both male and female organs. The male organ makes pollen which falls only a few millimeters in order to fertilize the female organ on the same flower. In theory pollen from one onion could fertilize another onion but the home team advantage of co-located male and female organs is huge.
Jones' method of creating hybrid onions pivoted on the observation that some rare onion plants make flowers but are nonetheless sterile. They rely on an alternative method of propagation. Jones hypothesized that the mechanism of onion sterility might be hereditary and that it could be used to control the 'slam dunk' self-pollenation of the average onion. He was right but it took many years to trial and error to bring the technique to a large scale. His first and most famous hybrid onion was "Granex" released in 1952. When Granex was planted in Georgia it was renamed "Videllia" and the rest is onion history. Today there are many hybrid onions of varying types but all have been created using Jones' insights.
A recent addition to the hybrid sweet onion clan is the 1015Y onion. It was developed in the 1980s by Dr. Leonard Pike from Texas A&M University. Pike's group was looking for a way to make a tasty, large sweet onion that would resist a serious root infection caused by a fungus common in Texas soils. After years of labor his group introduced the "1015Y" onion. The "1015" appellation was the suggested planting date in south Texas (October, 15) and the "Y" reflected its yellow color. Marketers have dropped its technical name in favor of "Texas Supersweets" but people inside the Texas onion beltway know better and still refer to it as 1015.
The onions at hand are a new white variety of 1015Y. (Marketers are attempting to jump in early on this one and its being promoted as "Contessa".) The genetic controls over onion color are fairly well known. Five genes control the range of color in onions, giving them a palette of white, yellow, red and a rare purple or chartreuse to choose them. Most commercial white strains have a gene called "I" which is a dominant genetic ace card that shuts off any other color gene the onion might have. I'm betting that Contessa is an "II" genotype but I have been frustrated in my efforts to learn about Contessa's genetic wiring. My inquiry to the Texas onion farmer who sold me my plants was returned with the comment that "It's the same as 1015Y only its white. That's all we know."
So there you have it: a new white Texas sweet onion called "Contessa" or maybe "1015W". These plants started their life on a Texas ranch but were shipped and transplanted into my garden in Sonoma Valley of the Moon during a wet, cold February . Its genetic roots go back to mild onion forebearers in Spain and the Canary Islands. But its recent ancestry bear the traces of ingenious human tinkering because you and I like onions to taste a bit less like onions. Onions begat onions and human ingenuity begat more ingenuity. Originally there was yellow but now we have white. And that's all I know.
Vegetables of Interest, 2008