Developing and testing new halophyte crops: A case study of salt tolerance of two species of the Brassicaceae, Diplotaxis tenuifolia and Cochlearia officinalis

Diplotaxis tenuifolia (L.) and Cochlearia officinalis (L.) were presumed to be salt tolerant with potential as vegetable halophyte crops. The response to increasing salinity was analysed by means of the relative growth rate (RGR) and its components and mineral composition. No growth reductions occurred up to 100 mM NaCl for D. tenuifolia, whereas C. officinalis showed a 37% decrease in total dry weight at this concentration of NaCl, corresponding to a 9% decrease in RGR. The RGR at higher salinity levels (≥200 mM NaCl) showed reductions around 20% for both species, largely due to changes of leaf morphology (decrease in specific leaf area, increase in leaf succulence) rather than toxic leaf Na+ concentrations. In comparison to seven other species of the Brassicaceae, including salt sensitive and highly salt tolerant species, both D. tenuifolia and C. officinalis showed an intermediate response to increasing salinity. Both species were able to survive the highest salinity treatment (300 mM NaCl for D. tenuifolia and 400 mM NaCl for C. officinalis) and can be classified as salt tolerant with potential as vegetable crops for saline agriculture. Since D. tenuifolia is already in use as an agricultural crop, little constraints are foreseen for its introduction as a saline crop. Before C. officinalis can be used as a saline crop, agricultural practices and marketing still have to be addressed. A hands-on tool is provided for this process, which combines science, agronomy, the social system, and the business sector.

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► Diplotaxis tenuifolia (L.) and Cochlearia officinalis (L.) were evaluated for their potential use as halophyte crops.
► Diplotaxis tenuifolia showed no growth reductions at 100 mM NaCl, whereas C. officinalis decreased by 37% in total dry weight.
► Changes in leaf morphology were mostly responsible for growth reductions at higher salinities.
► Many aspects concerning agricultural practices and marketing still have to be addressed, for which a framework is presented.