Cultivating salt-tolerant crops like Salicornia - popularly known as samphire - will be a key to helping many communities maintain food security in the face of climate change.
Predicted sea-level rises and storm surges forcing seawater further inland make the need to increase the saline tolerance of crops more urgent, and for years scientists have been making advances in understanding how this works in plants. However, these discoveries have not yet translated into commercial varieties of salt-friendly plants for farmers to cultivate.
Researchers at KAUST - King Abdullah University of Science & Technology in Saudi Arabia, Vanessa Melino and Mark Tester say that this will change as priorities shift, and more effort is needed to improve performance of crops in salt-affected areas.
“Anything we can do to reduce the use of groundwater for food production, including the use of brackish water instead of fresh water in agricultural systems, will increase the sustainability of food production.”
“We need to reassess old techniques, such as grafting current crops with salt-tolerant hybrid rootstocks. Also, future crops can be produced by domesticating salt-tolerant wild species — an approach that is feasible in our lifetime,” says Tester, who has co-founded RedSea, a company producing crops using saltwater in water-scarce environments.
Increasing salinity in irrigation water is another threat. As groundwater is depleted, soil quality falls and soil salinity increases.
“Anything we can do to reduce the use of groundwater for food production, including the use of brackish water instead of fresh water in agricultural systems, will increase the sustainability of food production,” says Tester.
While much salinity-tolerance research has focused on cereals, the authors encourage targeting a wider range of plants — especially crops with high nutritional value, such as fruit and vegetables.
Using wild plants
For some crops, the use of close crop wild relatives — species that can hybridise with the crop species — is a promising option. Crops such as wheat, which have relatively limited natural variation in salinity tolerance, would benefit significantly from such wide crosses.
Other crops, like tomatoes, which have good abilities to hybridise with wild relatives, can also exploit such opportunities. New genetic tools provide a way to introduce salinity tolerance traits from distant crop wild relatives or even to domesticate salt-tolerant wild species.
“This will require a paradigm shift away from the crops we are familiar with to the evolution of new crops from plants that are currently wild and have an extraordinary ability to thrive in extreme environments,” says Melino, who leads research into Salicornia - also known as sea asparagus, sea pickle, glasswort and samphire - as a potential oilseed crop.
The authors believe the lack of progress in development of salt-tolerant varieties is due to plant breeders’ focus on maximising national yields, when they also need to take into consideration improvements to farmers livelihoods.
“Even if increases in yields are modest, the opportunity to reduce pressure on freshwater reserves by being able to use brackish water can make a substantial contribution to reducing the environmental footprint of agricultural production,” they conclude.