Salvaging the salty small holdings

When people interested in food security aren’t busy worrying about plateauing crop yields, they tend to be worrying about how much agricultural land we’re losing. We already use so much of the world for growing food crops (around a third) that there’s very little spare land left, and some of the techniques we use for growing crops lead to the land we already have being lost. When crops are grown in an area with insufficient rainfall they must be irrigated (i.e. watered). But all standing water, even if it doesn’t come from the sea, contains small traces of salts: just look at the label on a bottle of Evian. This means that over time, the land becomes saltier or salinised and since plants don’t like salty soil they struggle to grow there. 

Scientists at the IRRI (international rice research institute) have been working to try to breed a variety of rice that can tolerate salinity. An exotic sister species (i.e. closely related but different – the equivalent of something like Homo erectus to humans), Oryza coarctata,  does tolerate salt. It has salt glands in its leaves, which allow it to excrete the salt it takes up through its roots into the air. This is vital because it normally grows in brackish, salty water.

O. coarctata isn’t suitable for producing edible rice, so the genes that allow it to tolerate salty water must be bred into an edible cultivar (variety).  Unfortunately, it is actually very different to edible rice: so different, in fact, that until about a decade ago it was known as Porteresia coarctata and not even put in the same genus). Because it is quite divergent from rice, attempts to breed the two together have until now failed, but scientists from the Phillipines have finally reported success.

After 34 000 crosses between the plants, three embryos were rescued, and one of these has been successfully grown  into an adult plant. This is now ‘back crossed’ to the rice parent so that rather than having 50% of the rice genes and 50% of the genes of the salt-tolerant plant it will have as many genes from edible rice as possible. This process is expecting to take several generations and 4 to 5 years before the variety can be available for farmers.



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