Effect of saline water on seed germination and early seedling growth of the halophyte quinoa

Salinization is increasing on a global scale, decreasing average yields for most major crop plants. Investigationsinto salt resistance have, unfortunately, mainly been focused on conventional crops, with few studies screeningthe potential of available halophytes as new crops. This study has been carried out to investigate the mechanismsused by quinoa, a facultative halophytic species, in order to cope with high salt levels at various stages of its development.Quinoa is regarded as one of the crops that might sustain food security in this century, grown primarily for itsedible seeds with their high protein content and unique amino acid composition. Although the species has beendescribed as a facultative halophyte, and its tolerance to salt stress has been investigated, its physiological andmolecular responses to seawater (SW) and other salts have not been studied. We evaluated the effects of SW anddifferent salts on seed germination, seedling emergence and the antioxidative pathway of quinoa. Seeds were germinatedin Petri dishes and seedlings grown in pots with SW solutions (25, 50, 75 and 100 %) and NaCl, CaCl2, KCl andMgCl2 individually, at the concentrations in which they are present in SW. Our results demonstrated that all salts, atlower concentrations, increased the germination rate but not the germination percentages, compared with control(pure water). Conversely, seedlings were differently affected by treatments in respect to salt type and concentration.Growth parameters affected were root and shoot length, root morphology, fresh and dry weight, and water content.An efficient antioxidant mechanism was present in quinoa, activated by salts during germination and early seedlinggrowth, as shown by the activities of antioxidant enzymes. Total antioxidant capacity was always higher under saltstress than in water. Moreover, osmotic and ionic stress factors had different degrees of influence on germination anddevelopment.