Abstract
Almond trees are very sensitive to salinity, and saline water is the only alternative for irrigation in many semiarid regions. Thus, the use of salt-tolerant rootstocks may allow an economically-feasible yield under saline irrigation. In this study, we evaluated the effects of chloride salts on plant secondary metabolites in red-and green-leaf almond biotypes to improve salt tolerance. one-year-old rooted cuttings of Bitter Almond (BA) and Garnem (GN15) rootstock seedlings were cultivated for 3 weeks under low-salinity water (control), or exposed to irrigation with CaCl2 (10mM), KCl (10mM), and NaCl (75 mM), alone and in combination, for 4 weeks. In green leaves of BA, the supplementation of NaCl solutions with CaCl2 significantly increased anthocyanin, petunidin, and polyphenol concentration, indicating a possible involvement of these compounds in cell osmoregulation. In GN15 rootstock, spermidine increased significantly from control when CaCl2 was added to control irrigation. However, the highest and most significant increase in both spermidine and putrescine in GN15 was caused by NaCl alone. The significant increase in polyamines, between control to NaCl treatment, in GN15 but not in BA rootstock, and the drop in antioxidant capacity in BA, but not in GN15, across treatments, suggest that GN15 may be more salt-tolerant than BA. Although the addition of CaCl2 or KCl may not have any benefit in mitigating salinity in almond rootstocks, spermidine and putrescine may have a role in helping almond rootstocks cope with salinity.d