AGRICULTURAL NEWS - Can we really feed nine billion people? That's the estimated global population in the year 2050. It should be possible, but things are looking tricky - especially when we also factor in the climatic instability caused by global warming.
1. Drought
Demands for water for human use and to grow crops are increasing, but changing weather patterns because of global warming mean we can’t rely on enough rain falling where we need it.
So how can crops still thrive in a warmer world? Back in the 1990s, a simple experiment was devised to test how grapes were affected by signals from their roots in dry soil.
Vines were grown with their roots split. They were given plentiful water through one half of their roots, but the others were not watered. The effect was astounding: the fruit yield was the same but only 70% of the water was used.
If plants reduce their water loss they can’t take up as much carbon dioxide for photosynthesis and thus growth. However it seems plants direct the resources they do have to their fruit and seeds, in order to protect the next generation. This works well for us humans: as fruits and seeds are frequently the edible parts of the plant, “partial root drying” often sustains crop yields.
2. Emerging diseases
Pathogens – anything which causes disease, such as a virus, bacterium or fungi – have always been a feature of agriculture and there are a number of current causes for concern. For example, a wheat rust fungus that current varieties have no resistance to is spreading from Africa to the Middle East.
Bananas are also an important staple crop for hundreds of millions of people in Africa, but a new variety of the fungus that causes Panama disease has devastated plantations of previously-resistant varieties and is spreading from Southeast Asia.
Crops often already have resistance mechanisms that could stop a new pathogen in its tracks. What they lack is the information that they are under attack and should turn their defences on.
Plants use “R proteins” to detect invading pathogens and trigger their defence responses in a way analogous to our antibodies.
Plants use “R proteins” to detect invading pathogens and trigger their defence responses in a way analogous to our antibodies.
An R protein from another variety of the same species or sometimes even from another plant species resistant to the pathogen can be copied into a vulnerable crop by genetic engineering, where it will identify the pathogen and activate defences against it.
In the long run, it may be possible to defeat evolving pathogens by equipping crops with a barrage of different R proteins so that evading one way of detecting them is not enough.
3. Salty soils
Water used for irrigation isn’t pure H2O and often it contains minerals including sodium and calcium salts. When a crop takes up the water these substances are left behind in the soil, just as mineral impurities in tap water cause your kettle to fur up. Salts accumulated in soil now affect crop yields in many parts of the world.
3. Salty soils
Water used for irrigation isn’t pure H2O and often it contains minerals including sodium and calcium salts. When a crop takes up the water these substances are left behind in the soil, just as mineral impurities in tap water cause your kettle to fur up. Salts accumulated in soil now affect crop yields in many parts of the world.
