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Tiny lettuce seed very picky about where it grows
The Yuma Sun is taking a behind-the-scenes look at agriculture in Yuma. This story is one in an ongoing series. Here are some other stories in this series:
Without the humble lettuce seed, the Yuma agriculture industry would lose out on some serious green.
According to the Agriculture Marketing Resource Center, the value of all U.S. lettuce production in 2010 was approximately $2.2 billion, making it the leading vegetable crop in terms of value.
California and Arizona account for about 98 percent of commercial domestic output of lettuce, with the majority of production from November through March occurring in Yuma and the Imperial Valley.
Once finished, the leafy greens are exported across the United States, as well as to Canada, Mexico and nations all over the world.
Lettuce seeds are very small and very fragile, said Rick Rademacher, who works for 3 Star Lettuce, a Yuma company that specializes in seed production. “Lettuce seed is very fine, it is almost like dust.”
The seed is also very picky about where it will grow, so area farmers rely on seed companies to provide them a tailor-made product best suited for their individual needs.
“We are looking for that magic combination, if you will, of that right variety of seed at the right time of year, on the right piece of ground, that fits the needs of the grower and the shipper,” Rademacher said.
“You change one thing, it changes everything. We have to try a lot of different varieties to see which one fits individual circumstances. What works for one guy may not work for another based on growing style, the soil he's got and time of year.”
While soil, labor, water, fertilizer and pesticides are all necessary for the growth of a crop, the seed is very important, “because that is the crop,” Rademacher said.
“You are buying the crop in an embryonic state and planting it in a field and giving it everything it needs to grow. In all the decisions you can make in planting a lettuce crop, choosing the right seed is very important.”
There are currently about 100 different varieties of head lettuce growers can choose from, “and a lot of those choices are based on preference, growing style, the quality that the shipper wants for their customers — it gets pretty involved,” Rademacher said. “Our job is to find varieties for our customers that fit all their needs.”
Each field may need a custom seed.
“Some varieties do better in heavier soil, some in light soil. Some do better in the fall and some do better in the spring,” Rademacher said.
3 Star Lettuce conducts extensive research and development on each of its seed varieties before offering it to growers.
Since there are many microclimates throughout Yuma County, growers must be very careful about choosing the proper lettuce seeds.
“Some of them are a half-mile from each other,” Rademacher said.
“A lot of it is really air currents. Normally Winterhaven and north Yuma Valley are the warmest, and as you go south it gets colder. Gadsden is a very cold spot. It's one of the coldest spots in the county.”
Dome Valley is a little warmer because it gets a lot of air movement going through Telegraph Pass, he added, noting that fields close to some mountains tend to be warmer because air swirls around them.
Thanks to enhancements in seed technology, lettuce growers in the Yuma area can plant and harvest their crops sooner than in previous decades.
One of the ways they do that is by speeding up the process of vernalization, which naturally happens in the seed during exposure to the prolonged cold of winter. The process must be completed before the seed can germinate.
In a natural setting, vernalization takes about five months. That time is cut to about one month using refrigeration techniques.
“You cold treat it and make it think it's going through the winter, and then it is ready to go,” Rademacher said.
Growers are also able to plant lettuce at the beginning of September instead of the end of that month, thanks to a “priming” process.
“Lettuce as a species doesn't like to germinate in anything above 85 degrees,” Rademacher said. That meant growers had to wait until the weather cooled in the past. But now the seeds are primed with special plant hormones that trick the plant into growing despite temperatures above 85 degrees.
“Priming actually takes it through the first step of germination,” Rademacher said.
Growers also use sprinklers, which can “reduce the temperature of a field by 15 degrees,” he added.
They can also have lettuce in the fields in midwinter, which was impossible 30 years ago.
“It was too cold,” Rademacher said. “But we have developed varieties with enough vigor to grow through the cold. We are really able to defy nature on a grand scale. It's all biology.”
Chris McDaniel can be reached at email@example.com or 539-6849.