Saving Our World–Chapter Twenty-Three–Drought Tolerant Crops

What people fail to realize is that we are living in a closed loop system. We can’t create water. We have the same amount of wateron this earth as the dinosaurs had. The only difference is the percentage of salt to fresh water that exists now. Our world produces enough water for life to survive. The only problem is that it is not spread across the planet evenly. This is mainly due to weather patterns, and physical structures that exist on the planet, ie Mountains. Another issue is the temperature on the planet is not even everywhere. The closer you get to the equator the hotter it gets and the colser you get to the polar ice caps the colder it gets. Now these are just general rules of thumb, because there are always exceptions to the rule. In the previous chapter I discussed desalination and water conservation, in this chapter I am going to concentrate on a very important aspect of conservation and that is drought tolerant crops.

This is very important, mainly because a large portion of our planet is arid or semi arid, and whikle we do have plenty of water, bringing it to these areas is not only quite difficult but expensive as well. In many instances these regions are also quite poor, with the exception being the middle east which has large oil reserves.

Agriculture uses approximately 70% of the world’s freshwater supply, and water managers are under mounting pressure to produce more food and fibre for a growing population while also reducing water waste and pollution and responding to a changing climate. In light of these challenges, more farmers are adopting innovative water management strategies, such as innovative irrigation systems and scheduling and methods to improve soil health. The Pacific Institute conducts research and works with innovative agricultural partners to identify and scale strategies to improve water management and ensure a vibrant agricultural system and global food security.

Drought tolerance is the ability to which a plant maintains its biomass production during arid or drought conditions. Some plants are naturally adapted to dry conditions, surviving with protection mechanisms such as desiccation tolerancedetoxification, or repair of xylem embolism. Other plants, specifically crops like cornwheat, and rice, have become increasingly tolerant to drought with new varieties created via genetic engineering.

The plants behind drought tolerance are complex and involve many pathways which allows plants to respond to specific sets of conditions at any given time. Some of these interactions include stomatal conductancecarotenoid degradation and anthocyanin accumulation, the intervention of osmoprotectants (such as sucroseglycine, and proline), ROS-scavenging enzymes. The molecular control of drought tolerance is also very complex and is influenced other factors such as environment and the developmental stage of the plant. This control consists mainly of transcriptional factors, such as dehydration-responsive element-binding protein (DREB), abscisic acid (ABA)-responsive element-binding factor (AREB), and NAM (no apical meristem).

Plants can be subjected to slowly developing water shortages (ie, taking days, weeks, or months), or they may face short-term deficits of water (ie, hours to days). In these situations, plants adapt by responding accordingly, minimizing water loss and maximizing water uptake. Plants are more susceptible to drought stress during the reproductive stages of growth, flowering and seed development. Therefore, the combination of short-term plus long-term responses allow for plants to produce a few viable seeds.

Natural drought tolerance adaptations

The scarlet globe mallow (Sphaeralcea coccinea) is a drought-escaping plant with natural drought tolerance. Some of its natural adaptations include silver-gray hairs that protect against drying; a deep root system; and having seeds that only germinate when conditions are favorable.

Plants in naturally arid conditions retain large amounts of biomass due to drought tolerance and can be classified into 4 categories of adaptation:

Drought-escaping plants: annuals that germinate and grow only during times of sufficient times of moisture to complete their life cycle.

Drought-evading plants: non-succulent perennials which restrict their growth only to periods of moisture availability.

Drought-enduring plants: also known as xerophytes, these evergreen shrubs have extensive root systems along with morphological and physiological adaptations which enable them to maintain growth even in times of extreme drought conditions.

Drought-resisting plants: also known as succulent perennials, they have water stored in their leaves and stems for sparing uses.

Structural adaptations

Many adaptations for dry conditions are structural, including the following:

-Adaptations of the stomata to reduce water loss, such as reduced numbers, sunken pits, waxy surfaces.

-Reduced number of leaves and their surface area.

-Water storage in succulent above-ground parts or water-filled tubers.

Crassulacean acid metabolism (CAM metabolism) allows plants to get carbon dioxide at night and store malic acid during the day, allowing photosynthesis to take place with minimized water loss.

-Adaptations in the root system to increase water absorption.

Trichomes (small hairs) on the leaves to absorb atmospheric water.

Drought-Tolerant Crops to Plant Amid Water Scarcity

Water scarcity is a growing concern. Lack of water from long, recurring droughts is increasingly dominating the food and agriculture world. It’s driven up the cost of groceries and put a dent in farmers’ yields. According to NASA scientists, the past two decades have been some of the driest conditions on record. And recent data from the federal government shows that more than half of all states are suffering from moderate drought or worse. 

For avid gardeners, especially in the West, the ongoing water crisis is a good time to reconsider which crops to put in the ground. There are some plants, such as rice, almonds and citrus, that require large amounts of water to thrive.

Others, categorized as drought-tolerant crops, require very little. So, if you’re short on water, there’s no need to let it stop you from growing. There are a number of crops you can plant that require minimal water input. Dive into our guide that lays out a variety of planting options.

In recent decades, research has increased to see how food crops cope with dry conditions, and scientists are breeding and crossing seeds to make them more drought-tolerant.

But major obstacles exist in scaling up their use.

“Getting new crop varieties into the hands of a large number of farmers quickly is the challenge,” said Robert Asiedu, head of biotechnology and genetic improvement at the International Institute of Tropical Agriculture, a research center based in Nigeria.

“It can be five to 10 years before large quantities of new varieties reach farmers… That’s the main bottleneck now.”

It is crucial for farmers to grow drought-resistant crops as part of a range of pro-active measures, experts say.

For example, soil degradation and deforestation exacerbate the effects of drought because soil loses its ability to retain water, so farmers must improve soil fertility and irrigation practices.

Below are some of the drought-tolerant crops and methods farmers across the world are using to combat drought:


Staple food crops like sorghum, cassava, sweet potato, pearl millet, cowpea and groundnut are naturally more drought-tolerant than maize.

For centuries, farmers in parts of West Africa have grown maize alongside cassava and sweet potatoes.

The practice known as intercropping – growing two or more crops together – means farmers have another crop to fall back on when maize harvests fail because of poor rainfall.

In recent decades, research has increased to see how food crops cope with dry conditions, and scientists are breeding and crossing seeds to make them more drought-tolerant.

But major obstacles exist in scaling up their use.

“Getting new crop varieties into the hands of a large number of farmers quickly is the challenge,” said Robert Asiedu, head of biotechnology and genetic improvement at the International Institute of Tropical Agriculture, a research center based in Nigeria.

“It can be five to 10 years before large quantities of new varieties reach farmers… That’s the main bottleneck now.”

It is crucial for farmers to grow drought-resistant crops as part of a range of pro-active measures, experts say.

For example, soil degradation and deforestation exacerbate the effects of drought because soil loses its ability to retain water, so farmers must improve soil fertility and irrigation practices.

Below are some of the drought-tolerant crops and methods farmers across the world are using to combat drought:


Staple food crops like sorghum, cassava, sweet potato, pearl millet, cowpea and groundnut are naturally more drought-tolerant than maize.

For centuries, farmers in parts of West Africa have grown maize alongside cassava and sweet potatoes.

The practice known as intercropping – growing two or more crops together – means farmers have another crop to fall back on when maize harvests fail because of poor rainfall.


Cowpea, also known as black-eyed pea, is mainly grown by small farmers in more than 80 countries, from Nigeria to Brazil.

Cowpea thrives in parched soils and drought-prone areas where its roots can grow with as little as 300 mm (11.8 inches) of rainfall per year. Once cowpea seeds have enough moisture to take root, the plants can survive drought.

The stems and stalks of the high protein grain can also be used as fodder for livestock.

Often intercropped with maize and cotton, cowpea plants provide shade and dense cover that help protect soil and preserve moisture.

Researchers are trying to map the genes found in cowpea to produce improved drought-resistant varieties.


Chickpea is one of the most important grain legume crops in the world. Thanks to its drought resistance, it is widely grown among small farmers in dryland areas of South Asia and in China.

Scientists in Australia are leading the way in research to enhance drought tolerance in chickpeas and to better understand how the food crop adapts to prolonged dry spells.


Shifting rainfall patterns, often linked to climate change, have shortened the rainy season in many countries worldwide.

Hardest hit are small-scale and subsistence farmers as they largely depend on rain-fed crops for their livelihoods.

To adapt, farmers are increasingly planting new varieties of food crops that take less time to grow.

New varieties need 90 to 110 days to mature – against 120 days plus for traditional crops – and can survive without rain for three weeks.

In recent years, early-maturing food crops have been adopted by tens of millions of farmers in sub-Saharan Africa.


Chia, a flowering plant, is grown for its edible seeds and is known to thrive in hot and dry weather.

Once widely grown by the ancient Aztecs of Central America, chia is being rediscovered by small farmers across Latin America, including Guatemala, Bolivia, Nicaragua and Ecuador.

High in protein, chia seeds can be eaten whole, ground into flour and pressed for oil.


With its brilliant blue blossom, the tarwi pea plant stands out from the rest in the field.

Once grown centuries ago by the Incas, more Andean subsistence farming communities, particularly in Bolivia’s highlands, are growing tarwi again.

The drought-resistant seeds are nutritious, high in protein and a source of cooking oil.


Maize is one of the world’s most important cereal crops.

In the past decade, farmers – especially in sub-Saharan Africa – have tried new strains that can withstand drought, allowing crops to grow when there is little or no rain.

Maize has also been genetically modified to include the desired DNA traits that thrive in drought conditions.

A 2010 study found that the widespread adoption of drought-tolerant varieties could boost maize harvests in 13 African countries by 10-34 percent.


Beans feature on any given plate in most of Latin America.

In drought-hit Central America – Guatemala, El Salvador and Honduras – prolonged dry spells since mid-2014, linked to the El Nino weather phenomenon, have decimated food harvests.

In 2015 alone, drought in these countries left 3.5 million people in need of food aid, prompting scientists to look for varieties of bean that can withstand drought.

“It is a priority in all the research centers to develop these new varieties of crops,” said Tito Diaz, subregional coordinator for Mesoamerica at the U.N. Food and Agriculture Organization (FAO). Some have been successful, as in El Salvador.

Farmers there recently started to grow a new variety of drought-tolerant bean, named after the country’s National Center for Agricultural and Forestry Technology (CENTA) where the research took place. The CENTA-EAC bean is a hybrid, made from crossing black and red beans after years of trial and error.

In Nicaragua, farmers are also growing a new variety of red bean, INTA-Tomabu, which can thrive with little rainfall.

Figs on a branch.


Fig trees need to be planted in a spot that has seven to eight hours of full sun. This plant also needs well-draining soil, with a pH anywhere from 6.0 to 6.5. Sandy soil is preferred over loamy or clay solutions. 

Plant your trees in late fall to early spring. In addition to full sunlight, fig trees appreciate a lot of room. If you’re planting more than one tree, make sure they have 15 to 20 feet between them. We suggest providing your figs with somewhere between 1 and 1½ inches of water per week—either from rainfall or irrigation. You will know if it needs to be watered if its foliage starts to turn yellow or its leaves drop off. 

Improve a new tree’s chance of survival by planting it so that its roots are two to four inches deeper than they were in the tree’s nursery container. Fig trees planted in the ground may take eight to 10 years after planting before they begin fruit production. The common fig, Alma, Brown Turkey or Black Mission are all popular options. 

Hardiness zones: 8-11

Grapevines are resilient plants. 


Once they have grown to establish long, deep root systems, grapevines can sustain prolonged periods of time without water. They should be planted in a spot that has six to eight hours of sun each day. Grapes prefer well-draining, sandy, loamy soil. Avoid planting anywhere near areas that collect water after it rains, as these plants don’t tolerate wet conditions very well.

If there’s no rainfall, saturate the soil at the base of each vine every seven to 10 days. If the leaves are wilting and the fruit is small, hard and dry, your vines need more water. If the leaves of your grapes are yellowing or if the tips of the leaves turn brown, this means you’ve watered it too much.

Read our guide to growing wine grapes for more information on planting and harvesting. On average, it can take two to three years for your crop to start bearing fruit. 

Hardiness Zones: 7-10 

Goji berries.

Goji berries 

Good news: You can still plant a superfood with limited water needs. Pick a spot with full-day sun. Goji berries can tolerate many types of soil, but they prefer an environment that is well-draining with a pH ranging from 6.5 to 7.0.

If you have more than one plant, it should be spaced three to five feet apart within the row and at least six to eight feet apart between rows. This is to provide room for their root systems. It’s also important to note that the sandier your soil is, the more likely it will need to be watered. A good general rule, however, is to apply approximately one inch of water per week. 

Because goji is a member of the nightshade family, it will also need to be pruned after the first year. If growing from seed, sow them indoors about six to eight weeks before the last frost. If opting for a tree or shrub, plant in the early spring. 

Goji plants will begin producing fruit when plants are two years old. Maximum production will not be reached until three to five years after planting. You can harvest them 35 days after full bloom. The two most popular varieties available to all growers are Crimson Star and Phoenix Tears. 

Hardiness zones: 5-9

Mustard greens. 

Mustard greens  

Also known as curly or curled mustard, mustard spinach, Indian mustard or leaf mustard, mustard greens are known for their peppery taste that bites like that of a radish. Plant your mustard greens in loamy, rich and well-draining soil with a pH of 6.5 to 6.8. They also fare best in a spot that has full sun or partial shade. Mustard greens will require one to two inches of water each week. 

If you’re growing from seed, you can start them outdoors three weeks before your last frost date.

The Tendergreen or Southern Giant Curled are both varieties with low-maintenance water needs. On average, it takes anywhere from 35 to 70 days for mustard greens to be ready to harvest. You can cut the outer leaves, leaving the center in place to continue growing and produce more greens. Or you can treat the plant in a cut-and-come again fashion, cutting all the leaves to three to four inches from the ground and leaving the stub to re-grow. 

Hardiness zone: 6-11

An okra plant. 


As a staple in many southern dishes, it may not come as a surprise that okra can withstand the heat and will fare without copious amounts of water. For varieties that are extra tolerant to dryness, we suggest Hill Country Heirloom Red, Gold Coast or Jing Orange. 

Okra grows best when planted in a spot with full sun. Plant it in sandy, well-draining soil that’s high in organic matter. Provide one inch of water per square foot once a week. You can determine how to calculate that in gallons here. To improve the germination process, gently scratch the seeds with sandpaper and soak them in water for up to 24 hours before. You can plant your seeds with nine to 12 inches between them, so that seedling roots don’t get tangled. On average, this vegetable is harvestable within 60 days after planting.

For the best yields, plant okra in the spring two to three weeks after all danger of frost has passed. For a good fall crop, plant at least three months before the first fall frost.

Hardiness Zones: 6-11

A Japanese persimmon tree.


At first glance, one might mistake a persimmon for an orange tomato, but this fruit is prized for its silky texture and sweet, tangy flavor. Persimmons can tolerate a wide range of soil types, but well-draining loamy soil that is neutral or slightly acidic with a pH of 6.0 to 7.5 is best. 

For best results and to minimize immediate water needs, we suggest planting a tree over seedlings or seeds. If you do plant a tree, wait until the soil can be easily worked as you need to dig a hole as deep as the root ball and three times the width to accommodate its root system. 

Choose a spot with full sun. If you leave a perimeter of mulch that stretches a few inches around the tree trunk, it will help avoid moisture accumulation. During the growing season, provide your tree with one inch of water each week. It can take trees anywhere from two to 10 years to bear fruit, depending on the variety. Eureka, Saijo or Texas persimmons are all good drought-tolerant choices. 

Hardiness Zones: 5-11 

Pitaya, also called dragon fruit. 


Pitaya, also known as dragon fruit, is the fruit of cactus species native to the Americas. That makes it an attractive—and tasty—option.

This tropical crop should be planted in a spot with well-draining soil and full sunlight. Ideal pH level for its soil is between 6.0 and 7.0. Provide about one inch of water per square foot—or the first six inches of soil. A good rule of thumb would be to do this once a week or when the first two inches of soil are completely dry. Mulching around the base of the plant can help the soil retain its moisture. 

You can grow pitaya by seed, cuttings or by purchasing it as a plant. Pitaya will not grow in cold climates, so make sure that the temperature is above 40°F year-round. The optimal temperature is 65-80°F. If grown from a seed, it takes up to seven years to bear fruit. If planted as a young plant, it typically takes two years. You will know your fruit is ready when the flaps on the outer skin begin to wither. Twist off each fruit from the stem to harvest. 

Hardiness zones10-12

Pole beans. 

Pole beans 

Did you know that pole beans produce two to three times as much crop as bush beans would in the same amount of space? They rely on residual water found in the soil. They also prefer a spot with full sun and well-draining soil that has a pH level of 6.0 to 6.5. 

For drought-hardy varieties, opt for the Rattlesnake or Preacher Bean. Willow Leaf, Louisiana Purple Pod, Worchester Indian Red, Ruth Bible and Garden of Eden Romano are all great options.

Upon planting, wait until the soil temperature is above 60°F. That could occur as early as April in southern climate zones and as late as June in cooler northern regions.

When it’s time to plant, ensure that there are three inches of space between each seed. This vegetable needs one inch of water for every square foot once a week. And it takes about 65 to 75 days for the plant to mature. 

Hardiness Zones: 3-11

A bounty of rhubarb. 


Rhubarb is drought-tolerant because of its fibrous root systems, but it’s also cold-hardy, too! It thrives in soil with a pH level ranging from 5.0 to 6.8. When planting, find an area that has full sun with good drainage. Many gardeners also plant them in raised beds. 

Victoria, Macdonald or Valentine are popular variety choices. Rhubarb is typically grown from crowns, which look like root stubs. You can purchase these from your nursery or local seed company. Crowns can be planted in fall or spring. But if you want to start with seed, we suggest starting indoors eight to 10 weeks before the end of spring or the last frost. 

When planting, place each crown upright in the planting hole with the buds one to two inches below the soil surface. Space the plants about three feet apart. After planting, water so that the top four inches of soil is soaked. It should watered every seven to 10 days. 

After planting, it’s best to wait two growing seasons before harvesting any stalks. The two-year establishment period allows the plants to become strong and productive. In its third year, rhubarb can be harvested over a four-week period. And in the weeks following, stalks can be harvested for eight to 10 weeks.

Hardiness zones: 3-8

Swiss chard. 

Swiss chard 

Swiss chard is a good leafy green option for those either looking to cut back on their water use or needing to do so. Not only is it drought-tolerant, it’s also cold-hardy. Your chard will prefer to be grown in a spot with full sun and rich, well-draining soil. Its pH level can be anywhere between 6.0 and 8.0. 

When planting, ensure that seeds are two inches apart from each other. Its water needs are roughly one to 1½  inches of water each week. If hand watering, be sure not to get the plants wet. Wet foliage promotes disease or fungi, so apply water at the base of the plants, under the leaves instead. 

On average, it takes about 50 to 70 days before harvest. The ideal time to plant is from early spring to mid-summer, and optimal soil temperature is 50-85°F. Bright Lights, Lucullus and Fordhook Giant are all great options, although most chard varieties are pretty drought-resistant. 

Hardiness zones: 3-10

Water scarcity aggravates poverty and hunger

The heat wave in India and Pakistan is just one example of how extreme and less predictable weather conditions affect low-income communities. “As over 80 percent of our freshwater consumption is accounted for by agriculture, water scarcity directly impacts food security and exacerbates poverty and hunger,” explains Dr. Suhas P. Wani, Former Director of the ICRISAT (International Crops Research Institute for the Semi-Arid Tropics) Development Center and consultant to the Asian Development Bank in Manila.

Without action, Suhas warns, the number of people suffering from hunger could increase by 10 million every year globally. 

Livelihoods are also affected in more developed regions of the world. Severe drought in 2021 caused the California agriculture industry to shrink by an estimated 8,745 jobs and shoulder $1.2 billion in direct costs as water cutbacks forced growers to fallow farmland and pump more groundwater from wells, according to new research. 

Hoover Dam, Lake Mead, drought
Formed by the Hoover Dam, Lake Mead is the largest reservoir in the United States. It is at an all-time low.

Since 2015, droughts in Europe have become more severe than any over the past 2,100 years, according to a study published in March 2021 in the Nature Geoscience. The recent series of summer droughts in Europe have also brought devastating ecological, agricultural, and economic impacts.  

The European Environmental Agency EEA  expects that droughts and water scarcity will aggravate during the remainder of the century and states in a report that the changing climatic conditions are already putting cultivation in Europe under pressure, especially for Mediterranean crops such as olives and grapes.

The worrying paradox: In 2050, our planet will need to provide food for an estimated 9 to 10 billion people. That’s going to require a lot of water. Using water in a more sustainable manner and growing “more crops per drop” is the challenge we are facing globally. Technology and adapted farming practices could be part of the answer.

Fortunately, agriculture may be the sector with both the most to contribute and the most to gain in the fight against climate change and severe weather. Climate-adaptive farming offers a multitude of opportunities to reduce extreme weather events—and even to mitigate global warming itself. Along the way, transforming our agricultural system toward climate resilience will also significantly improve the lives of animals and the livelihoods of farmers while making healthier diets more accessible nationwide.

Achieving this vision will not be easy. But it is vital—both to ensure a secure the World food supply in the years ahead and to prevent the worst effects of global climate change.

Resources, “10 Drought-Tolerant Crops to Plant Amid Water Scarcity: These fruits and vegetables will thrive even in the hottest conditions.” By Lindsay Campbell;, “From new beans to ancient plants, drought-busting crops take root.” By Anastasia Moloney;, “Drought Tolerance.” By Wikipedia Editors;, “Severe Droughts Require Action to Avoid Future Food Crisis.”By Stella Salvo;, “Extreme Weather and US Agriculture.” By Stray Dog Institute;, “Common weed may be ‘super plant’ that holds key to drought-resistant crops.” By Bill Hathaway;


Common weed may be ‘super plant’ that holds key to drought-resistant crops

A common weed harbors important clues about how to create drought resistant crops in a world beset by climate change.

Yale scientists describe how Portulaca oleracea, commonly known as purslane, integrates two distinct metabolic pathways to create a novel type of photosynthesis that enables the weed to endure drought while remaining highly productive, they report August 5 in the journal Science Advances.

“This is a very rare combination of traits and has created a kind of ‘super plant’ — one that could be potentially useful in endeavors such as crop engineering,” said Yale’s Erika Edwards, professor of ecology and evolutionary biology and senior author of the paper.

Plants have independently evolved a variety of distinct mechanisms to improve photosynthesis, the process by which green plants use sunlight to synthesize nutrients from carbon dioxide and water. For instance, corn and sugarcane evolved what is called C4 photosynthesis, which allows the plant to remain productive under high temperatures. Succulents such as cacti and agaves possess another type called CAM photosynthesis, which helps them survive in deserts and other areas with little water. Both C4 and CAM serve different functions but recruit the same biochemical pathway to act as “add-ons” to regular photosynthesis.

What makes the weed purslane unique is that it possesses both of these evolutionary adaptations — which allows it to be both highly productive and also very drought tolerant, an unlikely combination for a plant. Most scientists believed that C4 and CAM operated independently within leaves of purslane.

But the Yale team, led by co-corresponding authors and postdoctoral scholars Jose Moreno-Villena and Haoran Zhou, conducted a spatial analysis of gene expression within the leaves of purslane and found that C4 and CAM activity are totally integrated. They operate in the same cells, with products of CAM reactions being processed by the C4 pathway. This system provides unusual levels of protection for a C4 plant in times of drought.

The researchers also built metabolic flux models that predicted the emergence of an integrated C4+CAM system that mirrors their experimental results.

Understanding this novel metabolic pathway could help scientists devise new ways to engineer crops such as corn to help withstand prolonged drought, the authors say.

“In terms of engineering a CAM cycle into a C4 crop, such as maize, there is still a lot of work to do before that could become a reality,” said Edwards. “But what we’ve shown is that the two pathways can be efficiently integrated and share products. C4 and CAM are more compatible than we had thought, which leads us to suspect that there are many more C4+CAM species out there, waiting to be discovered.”

Environmental Issues

Extreme temperatures can disrupt crop growth and reduce yields. Heatwaves also threaten livestock—both directly with potentially lethal heat stress and indirectly with losses of fertility, milk production, and resilience to disease.

Droughts will further dry out soils already depleted by industrial growing methods, threatening not only food crops but also animal feed crops, pastures, and the animals that rely on them. Satellite images have revealed increased browning of the land in the Southwest.

Wildfires will become more likely in the context of high temperatures and extended drought conditions.  Wildfires can leave severe impacts on agricultural land, killing crops through both burning and smoke damage.

Floods and the damage they cause can be extremely costly. High water can devastate crops and livestock, accelerate soil erosion, pollute water sources, and damage the infrastructure of farms. The costs of recovery burden farming communities and disrupt food distribution.