I believe that the secret to producing extremely drought-tolerant crops, which should go some way to providing food security in the world, lies in resurrection plants, pictured here, in an extremely droughted state. You might think that these plants look dead, but they're not. Give them water, and they will resurrect, green up, start growing, in 12 to 48 hours.
00:37
Now, why would I suggest that producing drought-tolerant crops will go towards providing food security? Well, the current world population is around 7 billion. And it's estimated that by 2050, we'll be between 9 and 10 billion people, with the bulk of this growth happening in Africa.
00:56
The food and agricultural organizations of the world have suggested that we need a 70 percent increase in current agricultural practice to meet that demand. Given that plants are at the base of the food chain, most of that's going to have to come from plants.
01:12
That percentage of 70 percent does not take into consideration the potential effects of climate change.
01:19
This is taken from a study by Dai published in 2011, where he took into consideration all the potential effects of climate change and expressed them -- amongst other things -- increased aridity due to lack of rain or infrequent rain. The areas in red shown here, are areas that until recently have been very successfully used for agriculture, but cannot anymore because of lack of rainfall. This is the situation that's predicted to happen in 2050. Much of Africa, in fact, much of the world, is going to be in trouble. We're going to have to think of some very smart ways of producing food. And preferably among them, some drought-tolerant crops.
02:00
The other thing to remember about Africa is that most of their agriculture is rainfed.
02:07
Now, making drought-tolerant crops is not the easiest thing in the world. And the reason for this is water. Water is essential to life on this planet. All living, actively metabolizing organisms, from microbes to you and I, are comprised predominately of water. All life reactions happen in water. And loss of a small amount of water results in death. You and I are 65 percent water -- we lose one percent of that, we die. But we can make behavioral changes to avoid that. Plants can't. They're stuck in the ground. And so in the first instance they have a little bit more water than us, about 95 percent water, and they can lose a little bit more than us, like 10 to about 70 percent, depending on the species, but for short periods only.
02:55
Most of them will either try to resist or avoid water loss. So extreme examples of resistors can be found in succulents. They tend to be small, very attractive, but they hold onto their water at such great cost that they grow extremely slowly. Examples of avoidance of water loss are found in trees and shrubs. They send down very deep roots, mine subterranean water supplies and just keep flushing it through them at all times, keeping themselves hydrated.
03:24
The one on the right is called a baobab. It's also called the upside-down tree, simply because the proportion of roots to shoots is so great that it looks like the tree has been planted upside down. And of course the roots are required for hydration of that plant.
03:39
And probably the most common strategy of avoidance is found in annuals. Annuals make up the bulk of our plant food supplies. Up the west coast of my country, for much of the year you don't see much vegetation growth. But come the spring rains, you get this: flowering of the desert.
03:58
The strategy in annuals, is to grow only in the rainy season. At the end of that season they produce a seed, which is dry, eight to 10 percent water, but very much alive. And anything that is that dry and still alive, we call desiccation-tolerant.
04:14
In the desiccated state, what seeds can do is lie in extremes of environment for prolonged periods of time. The next time the rainy season comes, they germinate and grow, and the whole cycle just starts again.
04:27
It's widely believed that the evolution of desiccation-tolerant seeds allowed the colonization and the radiation of flowering plants, or angiosperms, onto land.
04:37
But back to annuals as our major form of food supplies. Wheat, rice and maize form 95 percent of our plant food supplies. And it's been a great strategy because in a short space of time you can produce a lot of seed. Seeds are energy-rich so there's a lot of food calories, you can store it in times of plenty for times of famine, but there's a downside. The vegetative tissues, the roots and leaves of annuals, do not have much by way of inherent resistance, avoidance or tolerance characteristics. They just don't need them. They grow in the rainy season and they've got a seed to help them survive the rest of the year.