Desert spuds: The quest to improve potato growth in the arid, salty Middle East

Potato farming is a challenge anywhere. But try it in an arid environment where the little water available usually is salty—and where imported seed often contains pathogens that are deadly to potatoes in your region.

Add religious, ethnic and political tensions to the mix, and you’ll see what CALS plant pathology professor Amy Charkowski and an international team of scientists faced as they sought to advance the cultivation of seed potatoes in Israel, Lebanon, Egypt, Morocco and the United States. The five-year, $1 million program, funded by USAID-MERC, or Mid-East Regional Cooperation, began in 2005.

Potato is an important crop in Morocco and Israel, but most of the certified seed potatoes planted there are imported from Europe—and they sometimes contain pathogens that are under quarantine in the Middle East. Establishing a local potato seed industry is considered important both to diminish the introduction of diseases and to enhance local economies.

The fact that potatoes are vegetatively propagated—a new plant is grown from a chunk of tuber rather than from true seed—makes them extremely susceptible to disease.

“Potato is really hard to grow because whatever the main plant gets, all the tubers have. If you don’t take great care in seed production, you can get a 75 percent yield reduction pretty quickly just from disease pressure,” says Charkowski, who also serves as administrative director of the Wisconsin Seed Potato Certification Program.

To avoid that kind of fallout, pathogen detection at the seed level is crucial. “You want the detection method to be accurate, you want it to be cheap, and you want it to be really efficient,” Charkowski says. “But common methods here—based on polymerase chain reaction—are not really applicable to most of the rest of the world, including, actually, here. It’s too time-consuming and expensive. You don’t want a method that costs $5 a sample. You need methods that are in the pennies per sample.”

That’s what the team was able to develop, mostly building upon work done by a Lebanese colleague.

“It was technology transfer from Lebanon to the U.S.,” says Charkowski. “We’ve been able to modify a detection assay that is very inexpensive. It’s not a novel method, it just hadn’t been developed for potato virus detection. It’s now being used by about four labs here on campus. The low cost has allowed us to do a lot of experiments we never could have done before because we couldn’t have afforded them.”

The method, called DBIA—dot blot immunoassay—is considerably less expensive than the currently more widely used ELISA (enzyme-linked immuno-sorbent assay). “In our program now we do several thousand ELISAs per year for the farmers,” says Charkowski. “So, the comparison is doing 2,000 tests at $1.50 apiece versus 15 cents apiece.”

In addition to disease, another big obstacle is salinity. Previous work in Israel had demonstrated the feasibility of growing potatoes with saline water. This project supported additional work by Israeli and Lebanese scientists on seed potato production with saline water—an effort that was successful. Demonstrations were conducted in Israel, Morocco and Egypt, countries with a range of water availability and soil and water salinity.

“There’s definitely a genetic component to it,” notes Charkowski. “Some varieties do much better with saline water than others. There’s potential to breed improved varieties, and possible parents have been identified for that.”

Water challenges in the Middle East got Charkowski thinking about broader applications for work her lab group has been doing in Wisconsin cultivating seed potatoes in a greenhouse hydroponic system. The method requires far less water than conventional growing in soil—which means it could be useful in the Middle East and other arid areas.

“Our rough estimates are that we’d need about a quarter to a fifth the amount of water to produce the same amount of seed. You’re using water very efficiently. And you’re using greenhouse space very efficiently,” says Charkowski. “You also don’t have as many pathogen issues because you don’t have to worry about soil-borne pathogens. So the system is applicable anywhere, and I think it would be very appropriate for that region.”

She shares these findings and others with Middle East colleagues she met through MERC—an example of how international collaboration has benefits well beyond the immediate project. In particular she values being part of a science community in which people from a wide range of Middle Eastern cultures have had a rare chance to interact with relatively little political baggage.

“Every year we meet, and we are able to get scientists from Morocco, Egypt, Israel, Lebanon and sometimes Jordan and Palestine together, because there are multiple MERC projects that work together,” Charkowski says. “We are all able to get together in a room and share information. This is actually a lot more complicated than it sounds.”

Indeed, working and traveling in the Middle East has been an enormous learning experience, as Charkowski describes it.

She has visited some extraordinary places, such as “the lowest farm in the world” on the edge of the Dead Sea, 1,312 feet below sea level. It is where, as the Bible would have it, Lot’s wife turned into a pillar of salt.

“They’ve got this amazing greenhouse complex and farms there,” says Charkowski. “They grow date palms and a lot of greens and herbs for export to Europe. They obviously can’t use Dead Sea water because it’s just solid salt. So they have to figure out how to pipe in water or use treated water in different parts of their agriculture. It was phenomenal to me. It looked like a very prosperous farm.”

But there are stark reminders, too, of challenges facing the region. In the Sinai Peninsula, Charkowski experienced a landscape without water. It was like visiting another planet, she says: “Nothing grows. There are no insects, there are no birds. It’s like being on the moon.”

At her conference hotel, guests were issued wristbands indicating what levels of water access they’d paid for. “At one price range you get your room and all your food, and at the higher price you also can have as much water as you want. Being scientists, we went for the cheaper one,” she says. “And so you could buy bottled water or at lunch they had a cooler and there’d be a guard posted there. You had to go and give money if you wanted water to drink.”

And then there was the place of women in the project, even women scientists—namely, at the back of the room, where women always sat during presentations. Men and women also flowed into separate rooms during breaks, Charkowski noted. “That happened at every meeting,” she says.

Political tensions occasionally were on display as well. The owner of a small hotel in rural Morocco felt compelled to post an armed guard outside of the team’s meeting room after learning townspeople were upset by “all those Israelis and Americans” gathered there.

Charkowski also has to serve as an e-mail way station between her Israeli colleagues and another colleague in the Middle East. “He will often e-mail me things and ask me to pass it on to Israel because he doesn’t want the Israeli e-mail trail,” Charkowski says. “And he can’t sign anything with the word ‘Israel’ on it. It would be a career-killer for him.”

The five-year project is winding down now. What role could its accomplishments play in helping to feed a hungry population?

“These are countries that, relative to the rest of Africa, are actually doing pretty well,” says Charkowski, referring to Morocco and Egypt. “But a typical yield in North Africa for crop potato is about half of what we see here. In sub-Saharan Africa, it’s about a quarter of what we see here. If they can develop a decent seed system, they should be able to double the yields that they’re seeing. That would be significant.”

Her project, she believes, has helped give the region the tools to do that. “I don’t think there’s a lot of novel research that has to go into helping seed production in other parts of the world,” Charkowski says. “It’s more taking the parts that are already available and making it a system that works in that country.”