Written by Elsa Matthus, CWR Project Correspondent
Under the Crop Wild Relatives Project, researchers from Bangladesh, Pakistan and the US have teamed up to develop carrots adapted to a hotter, drier and overall changing climate. As our cultivated carrots are highly sensitive to stresses such as heat, drought and salt, the team turned to wild carrots.
Half a carrot a day
Global carrot production has increased fivefold since the 1970’s. It is not a staple, but “economically speaking, it is a high value crop” says Philipp Simon, Professor for Horticulture at the University of Wisconsin. “People who have some carrots left over to sell at the market after feeding their families, make good money. That makes it a valuable crop in developing countries.” Simon should know, having worked in carrot genetics for almost 40 years. He expands on the assets of carrots: they are tasty, versatile, and – while your tomatoes and cauliflowers go all squishy – easy to store for a long time.
More importantly, carrots are full to the brim with micronutrients, especially the precursor of Vitamin A. Vitamin A deficiency weakens immune systems, making diarrhoea and measles deadly diseases, and can lead to blindness. According to the World Health Organisation, an estimated 250 million preschool kids are deficient in the vitamin. This leads to half a million children going blind per year, half of whom die within a year of going blind. All of which is completely preventable.
“Half a carrot a day is enough to meet an individual’s need for vitamin A. This means a plot of land a square meter in size could provide all the vitamin A needed for a couple of adults, for a whole year,” Simon says.
All in all, the carrot sounds like the solution to a whole list of problems. But climate change is making it harder and harder for farmers to grow it. Soils are becoming drier and saltier in many places. And a good carrot needs loose and well-watered soils.
Carrot reality check
The race to make carrots climate resilient is on, even in parts of the world that can afford high-input farming systems such as the US. Simon explains: “When we started this project with the Crop Trust there wasn’t too much US demand for carrots adaptable to climate change. Now there has been a four-year drought in California, where most of US carrots are grown”.
“There has been almost no work done on adapting vegetable crops for climate change”, likely because vegetables such as carrots get first rights on irrigation. Crops grown without irrigation, such as upland rice and wheat, were the first casualties of extreme climates, and had to be adapted first. But now, the carrot is in the frontline, and not only in the US.
In Bangladesh, “carrot is a modern crop. Demand and therefore production are increasing day by day”, says Abdur Rahim, Professor at the Bangladesh Agricultural University. Unfortunately, yearly monsoons blow the salty water of the Bay of Bengal inland. “Ten percent of the land is affected by salinity, and about 15 percent of Bangladesh is in a drought and heat stress area. As the demand for carrots is high all over Bangladesh, we need good varieties to grow in such stress areas.”
At the other end of the Himalayas, in Pakistan, carrots are already more established, with the red carrot variety ‘T-29’ being essential for many traditional Pakistani dishes. However, Pakistan’s carrot yield is much lower than its potential, it has even been declining over the past 20 years. Professor Aamir Ali, from the University of Sargodha, translates this into what it means to farmers: “Only the top five per cent of Pakistani farmers make the money they could with their carrot fields.”
Coordinated by the Crop Trust, Ali, Rahim and Simon teamed up to make the carrot more stress resistant. In their search for a climate resilient carrot, they pulled biodiversity out of their hats, in the form of a couple of wild carrots.
If we jump back in time a few thousand years, the carrot was grown for its leaves and seeds rather than for its roots. This is still the case for many of its distant relatives. Think aromatic fennel seeds, and crunchy parsley leaves – it’s all the same botanical family. Domestication of the carrot root probably first occurred in Central Asia, which until today harbours the largest diversity of wild carrots. While early carrot history is still a bit hazy, or rather white, purple and yellow when it comes to root color, the orange carrot only emerged in the 18th century in the Netherlands. It’s only recently that cartoon bunnies began snacking on orange carrots. And plenty of wild carrots are still out there, small-rooted and surviving on their own.
“If the carrots are surviving in the wild without any human intervention, then that’s a good sign for traits like the climate change variables, heat, drought and salt. We can probably use that genetic variation in a commercialised type of crop”, Simon says.
“And that’s exactly what we are trying to do”, adds Rahim. “In fact, this is the first project on crop wild relatives working in the stress areas of Bangladesh”.
The idea is straightforward: first characterize some selected wild carrots for stress tolerance in the extreme field conditions of Bangladesh and Pakistan, then cross the most tolerant ones with the local cultivated varieties. Flavor meets stress tolerance. Backing field trials up with controlled laboratory experiments, Simon and colleagues recently sequenced the carrot genome, which will greatly help breeding efforts down the line. All of this work is driven by a legion of students in Bangladesh, Pakistan and the US. The capacity building happening out on the carrot fields, greenhouses and labs is something worth boasting about:
The faces of carrot research
So meet PhD student Majharul Mannan, one of the students from the Bangladesh Agricultural University working on wild carrots. He travels a good eight hours by bus to Satkhira every time he needs to evaluate his field experiments. Satkhira is in the South of Bangladesh, on the Bay of Bengal, and the field sites are swamped with salt. In most growing seasons, soil salinity levels are about triple what your average crop can handle. Last growing season, Majharul recorded these already saline soils to have doubled in salt concentration again. Surprisingly, some of the wild carrots survived these harsh conditions. Think about how long you would survive on a hot summer’s day, when the only drink available is a glass of water with a heaped teaspoon of salt stirred in. Yum. That is what the wild carrots can put up with for months.
“This is really interesting for breeding saline-resistant varieties, which will help a lot of people who live in the southern part of Bangladesh”, Majharul says. His supervisor Rahim is equally amazed: “Within the wild relatives, we have seen varieties tolerating salinity or drought. Most cultivated varieties are not tolerant to such stresses.”
In Pakistan, it’s Adeel, Aneela and Rameez pushing carrot research forward. None of these students had worked on carrots, let alone wild carrots, before starting on this Crop Wild Relative project. Now they travel dusty roads to their field sites, to evaluate carrots in areas that are too hot, or too dry, and pretty arduous to work in. Rameez reports first-hand what it looks like when crossing wild and cultivated carrots, and why the hard work pays off:
“You can see a combination of colors, like a yellow pith, orange pulp and a dark skin, all in one carrot! I really enjoy this beauty of nature.” Fellow student Adeel agrees: “My interest to work on this crop is increasing every day. I hope my dreams may come true and I may be known as ‘Carrot Boy’ – carrot is my passion now.”
Meanwhile, PhD student Adam Bolton at the University of Wisconsin complements the results gathered in Bangladesh and Pakistan with laboratory experiments. “The initial stages of salt stress are very similar to drought stress”, he says, as both stresses drastically reduce the water that is available to plants. Adam has no monsoon winds to blow in salty waters from the Bay of Bengal. “Here in Wisconsin, we don’t actually have access to soil with these stresses occurring naturally, so we are putting seeds in petri dishes with salt and evaluating which varieties manage to germinate under these harsh conditions.”
Way to go, carrot!
The way forward is clear: “What has been found to be tolerant in both Bangladesh and Pakistan is material we are actively working with and trying to cross with cultivated carrots”, says Adam. He knows his PhD work will only add a detail to the big picture, but that does not deter him from working hard. “Breeding takes a lot of time, especially when you are working with wild carrots, so if we could get something out there in the next 10 to 15 years that would be great.”
His supervisor Simon agrees. “You know, the easier task is to go to my shelf and pull off a carrot that is well adapted for US carrot production. Using carrot wild relatives that are not refined is hard. However, I think it is well appreciated that greater diversity will pay off in the long run.”
With the help of all project partners, the good news of stress tolerant wild carrots is reaching a growing group of students, the world’s future researchers. Equally important, the plant material generated by this project will be made available to the carrot breeding community. This is the first crucial step to include the stress resistance traits wild carrots have to offer into breeding programs.
No matter if your soil is salty or dry, or if you prefer red or orange carrots, eating half a carrot a day should be part of everybody’s daily diet. And this project will make sure everybody will be able to do so in the years to come.
This project is part of ‘Adapting Agriculture to Climate Change: Collecting, Protecting and Preparing Crop Wild Relatives’, funded by the Norwegian Government and coordinated by the Crop Trust and the Millennium Seed Bank, Kew.