Salt-loving plants: saviours of planet Earth?

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Photo by Marco Custódio

The UN Food and Agriculture Organisation predicts that by 2050 the world population will reach 9 billion mouths and WWF most recent ‘Living Planet Report’ says that humans already consume in 1 year the resources equivalent to 1.6 planet Earths(!). The actual state of over-exploitation and depletion of the planet’s resources are becoming part of our collective awareness and a growing concern at a societal and scientific levels are leading the way to the implementation of more ecologically sustainable methods for an exponentially growing food-production sector.
Global agriculture is largely dependent on salt-sensitive plants(named glycophytes) that only grow in soils with a very low-to-none salt content, which make these crops totally dependent on freshwater irrigation. Freshwater comprises now less than 4% of the world’s total water supply and from these total, 70% is locked up in ice and glaciers, 30% is in the ground and the directly available surface water constitute only 0.006% (!). Depletion of freshwater resources shows no signs to stop and reserves are rapidly deteriorating in many regions of the world.
More recently, a group of plants known as halophytes have captured the attention of the scientific community. They are salt-tolerant plants that grow in highly saline environments (e.g. salt marshes and other coastal ecosystems) to which they evolved to become perfectly adapted. These special plants could produce nearly all that glycophytes now produce and more, in terms of, for example, nutrition for humans and animals, bio-energy and bio-active pharmacological compounds. The advantages of switching to halophytes in the long-run include for instance:

  • Growth in conditions where glycophytes would perish: wastelands, deserts and seawater;
  • Liberation of freshwater sources used for conventional agriculture;
  • Sequestration (up to 20%) of carbon dioxide uptake in root zone, removing it from the atmosphere;
  • Integration in marine aquaculture systems to remediate nutrient-rich effluents (circular economy and ecossystem-based production framework);
  • Production of biodiesel;
  • Diversification of plant-based diets.

Many of those plants are edible, with a slight salty taste, and have been used by plant foragers for centuries. Nowadays, chefs all around the world are experimenting with them to garnish their seafood dishes and salads. They are valuable source of minerals and antioxidants and several bio-active molecules are being isolated in laboratory, including important lipophilic and phenolic compounds.

Just to tease you curiosity, in case you want to try these plants and make your own judgement (and most likely become a fan), here is a small list of species that you can find on specialised stores online or on your nearest salt-marsh:

  • Salicornia spp, Sarcocornia spp  (common names: samphire, sea asparagus, sea beans)
  • Aster tripolium (sea aster)
  • Halimione portulacoides (sea purslane)
  • Beta maritima (sea beet)
  • Crambe maritima (sea kale)
  • Nasturtium officinale (watercress)

If global halophytes agriculture do take off in the near-future we should, nonetheless, contain our optimism. There surely isn’t one power switch to reverse and resolve our environmental issues, and halophytes alone won’t save the planet, but added to other major advances in several areas addressing sustainable methods of energy harvest, from solar power to genetic engineering, we might be confident for a better future in the horizon (of course, we can’t forget politics to promote investments on these sustainable ventures, but that’s another story).

Anyways, be-aware of the halophytes!

More articles to read:
1. https://aeon.co/essays/are-halophytes-the-crop-of-the-future
2. http://www.aaiforesight.com/sites/default/files/FR_Bushnell_Where_Is_It_All_Going_Summer-Fall_2016.pdf
3. http://inhabitat.com/boeing-etihad-ge-and-mist-to-build-worlds-first-aquaculture-and-biofuel-plant-at-masdar-city/
4. http://science.sciencemag.org/content/322/5907/1478

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