Optimum growth and quality of the edible ice plant under saline conditions

Ice plant is a halophyte, known for its antioxidant activity and for being a highly functional food. It is capable of increasing its contents of health-promoting compounds when subjected to certain stresses such as salinity. The objective of this work was to determine the plant's best growing conditions to achieve both an optimal production of bioactive metabolites and high crop yield. Mesembryanthemum crystallinum were grown under semi-controlled conditions and four saline treatments were applied at: 0, 100, 200 and 300 mmol L^-1 sodium chloride (NaCl), respectively.

The 100 mmol L^-1 NaCl treatment induced a slight increase in shoot dry weight (DW) and enhanced the leaf area. At higher salinity levels, however, the shoot biomass decreased. The concentration of starch and total proteins declined as the concentration of salt increased, while the total soluble sugars (TSS) content was lower in 100 and 300 mmol L^-1 NaCl treatments. Proline increased in conditions over 100 mmol L^-1 NaCl. Furthermore, plants grown with 300 mmol L^-1 of NaCl presented the highest values of glutathione, ascorbic acid and vitamin C. Antioxidant enzymes activity and total phenolics increased with the severity of the salinity.

Ice plant accumulates high levels of health-promoting compounds when grown with 300 mmol L^-1 NaCl. A high concentration of beneficial compounds, however, is detrimental to the plant's growth. Moreover, 100 mmol L^-1 NaCl treatment not only improved the concentration of bioactive and antioxidant compounds but also preserved the crop yield. It could thus be interesting to promote the cultivation of this high nutritional value plant in environments of moderate salinity. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.