Toby Cox is a reporter for the Post and Courier's Rising Waters Lab, covering flooding, sea-level rise and community resilience. She graduated from the University of Virginia and Harvard Divinity School. Her previous work can be found in National Geographic, The Diplomat, Summerhouse DC, The Revealer, Harvard Divinity Bulletin and others. If you have a question, tip or story idea, reach out to her at [email protected]. You can reach her securely on Signal at 843-670-8651.
Jerry Breland surveyed the rows of peanut plants across the 30-acre field. Breland has 600 acres of this type of peanut, a variety destined for the peanut butter jar. He has another 100 acres of Virginia peanuts, the kind for snacking, roasting and, of course, boiling.
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The key to good boiled peanuts is to pick them early when they're still immature, Breland said. Boil a mature, dry peanut, and it'll end up hard and overly-crunchy with an unpleasant mouthfeel no matter how long you cook it, he said.
"You can't take a bad peanut and make a good boiled peanut out of it," Breland said. "Now, you can take a good peanut and make a bad boiled peanut out of it."
Breland is a fifth-generation farmer based just outside of Walterboro. He used to grow tobacco, but not anymore. Now, most of the money the farm makes comes from sweet corn, strawberries and peanuts. Sometimes, it's not enough, he said. If it rains too much or too little, or if it's too hot or too cold, the peanut plants struggle. All farmers can do is sow the seeds and hope for the best -- or, in Breland's case, pray.
"Farming has deepened my faith in the Lord because we're not in control," he said. "We're not in control."
If Breland were in control, he'd have it rain an inch a few times a week around 3 p.m. during the peanut growing season, which runs late-April through November. Then, he'd have the sun dry the soil out before dark so the plants don't mold overnight. But these Goldilocks conditions seem to be happening less and less, he said. Instead, he's noticed it'll rain a lot for a few weeks and then it won't rain at all.
Climate change is causing researchers concern over one of South Carolina's most popular snacks. Hotter temperatures can kill the pollen peanut plants need to reproduce. And rainfall -- whether too much or too little because of shifting weather patterns -- can negatively affect yield, causing farmers financial uncertainty.
But new research could hold some important answers. Perhaps the peanut plant can be cultivated to tolerate more heat. Perhaps the potency of the pollen can be protected. And maybe the allergic response some people have to peanuts can be ameliorated.
Stressed out
Heat and drought are the two main stressors on peanut plants. Though peanuts are tropical plants that thrive in warmer climates, they have a tipping point. When the temperatures reach beyond what the plants can tolerate, growth can be stunted, fewer peanuts are produced, and the plants become more susceptible to insects, bacteria and fungi. Some studies estimate that rising temperatures and prolonged heatwaves will reduce global peanut yields by up to 20 percent by 2050.
Farmers have a tipping point, too. If the yield gets smaller, so will their income -- though not their bills.
"It worries me a little bit that these weather patterns are changing," Breland said. "Extremes seem to be happening more often than not. It's cooler sometimes than it normally is, and it gets hotter than it normally gets."
Roughly 120 miles away at Clemson University's Pee Dee Research and Education Center, researchers are looking for solutions. If they can find and breed the peanuts genetically inclined to survive in a hotter world, it could make farmers' lives easier and keep peanuts on shelves even as temperatures rise.
"Everything is changing," said Sachin Rustgi, a professor of molecular breeding at Clemson. Our understanding must change, too, he added.
Rustgi researches allergens and heat impacts on crops, including peanuts. One of his most recent studies focused on peanut plant pollen and reproduction.
The peanut plant's small yellow flowers pollinate themselves without the help of bees or other pollen distributors. Once the ovary is fertilized, the flower will wilt away and give way to a stem called a peg. The peg will grow downward, burrowing into the soil. Each peg will grow a pod containing the seeds (the part we eat).
This whole process hinges on the pollen's ability to find the stigma (the female part of the plant that's connected to the ovary). Timing is everything, Rustgi said.
Heat can sterilize pollen. High temperatures can make pollen it doesn't kill sluggish, which means it likely won't reach the stigma in time and out-compete other pollen, Rustgi said. The outcome of both of these scenarios is fewer peanuts.
But pollen from some peanut plants is more heat-tolerant than from others. To find out which, Rustgi and his team planted seeds for 72 genetically distinct peanut plants. Once they were sown, researchers placed them in a controlled growth chamber about the size of a walk-in freezer located on the bottom floor of the research center. Access to the chamber is restricted to prevent exposure to pests, bacteria, fungi and whatever else might be hitching a ride on a pair of shoes.
The researchers replicated the conditions peanuts need to thrive from seed to seedling to plant: a daytime high of around 82 degrees Fahrenheit during the day and a nighttime low of around 72 degrees. They kept the relative humidity high at 70 percent and watered the plants regularly.
When five fully expanded leaves grew on the main stem of the plants, Rustgi cranked up the heat, exposing the plants to around 100 degrees Fahrenheit during the day and around 82 degrees Fahrenheit at night for 14 days in a row. These conditions were well beyond the plants' heat threshold, which is around 86 degrees Fahrenheit.
This scenario doesn't happen naturally in South Carolina, Rustgi said. There might be a few days where peanuts are exposed to high heat, but it's never constant for weeks at a time. The longest Breland's peanut plants were exposed to temperatures of 100 degrees and higher this year, for example, was four days in a row in July, according to the National Weather Service. But the researchers needed the conditions to be extreme to see which plants produced the strongest pollen under heat stress.
"We take microscope slides and we put a germination media on top, which is very sugar-based," said Zachary Jones, a researcher working with Rustgi. "Then when you put the pollen on there, the tubes in the pollen will extend like how it would in a flower, looking for the ovary to fertilize."
If the tube doesn't extend, the pollen is dead, Jones said.
The pollen study found that 23 of the 71 plant genotypes outperformed the Georgia Green, a peanut variety used as the control group, when placed under heat stress, Rustgi said.
Crossing these plants could lead to more heat-tolerant peanut lines, he said. It will take around five years before any new variety ends up on shelves.
'An evolving understanding'
Studying the impacts of heat on peanuts is relatively new, Rustgi said. And more research is needed to fully understand what heat does to peanuts on a molecular level.
One unanswered question is how heat affects the proteins in peanuts that cause allergies. In some heat-stressed peanut plants, Rustgi said, these toxic proteins were reduced, making the peanuts less allergenic. But it's also possible for heat to have the opposite effect, making them more allergenic. The sample wasn't large enough to say for certain, he said.
Rising temperatures and concerns about global food security drive Rustgi's research on how these crops could be made more resilient and less allergenic through cross-breeding and gene editing.
"(2050) used to seem very far away," he said. "Today, it seems like it's just in front of us. We have to act swiftly, otherwise it will just have detrimental consequences."
Protein-rich and affordable, peanuts are a major source of nutrients around the world, Rustgi said. They're a major cash crop in South Carolina, sixth to corn, soybeans, cotton, peaches and sod, according to the state's Department of Agriculture. Peanuts also are closely linked to local history and culture.
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The peanut is native to South America and was introduced to the United States in the 1700s by enslaved Africans. It became a commercially important crop in the South during the Civil War, providing protein to Confederate and Union soldiers, according to the National Peanut Board.
Peanuts gained popularity through the 1900s, when major technological improvements made harvesting them easier. Reese's peanut butter cups and Peanut M&Ms hit the shelves. Peanut butter became a pantry staple. The PB&J gained status as an iconic American sandwich. Roasted peanuts became a favorite snack among baseball fans, circus-goers and Texas Roadhouse patrons.
"(Baseball) fans have gravitated to (peanuts)," said Josh Shea, vice president of food and beverage for the Charleston RiverDogs. "It's easy. It's interactive as well because they're cracking the shell, whether it's boiled peanuts or roasted peanuts."
Boiled peanuts were declared the official snack of South Carolina in 2006.
Despite the heatwaves in July, Breland said it's been a good growing season so far. Each of his plants should produce a couple handfuls of peanuts. The 30-acre field should yield around 4,000 pounds.
He pulled up two of the plants and pinched his brow. Peanuts swung between the roots, but not as many as Breland was expecting.
"That really should have (more) peanuts on it," he said.
It takes about 145 days for this peanut variety to grow, and these plants were at roughly the midpoint. They still have time to produce more peanuts before they're harvested in November, he said.
If it doesn't get too hot.