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

Abstract

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 100mM 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 (≥200mM 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 (300mM NaCl for D. tenuifolia and 400mM 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.