Effect of foliar application of potassium iodate on strawberry tolerance to salinity stress

In this study, to evaluate the effect of foliar-applied iodate (5 and 50 mg/l KIO3) on the improvement of tolerance to salt stress (50 mM NaCl) in strawberry plants (Fragaria × ananassa Duch.), an experiment was under taken in complete randomized block design (RBD). The photosynthetic apparatus of strawberry was damaged at 50 mM NaCl, as indicated by a decrease in performance index (PIabs) coupled with lower values of photosynthetic electron transport chain components including the electron transport flux (φEo) and the inferred oxygen evolving complex activity (Fv/Fo) as well as higher levels of malondialdehyde (MDA). Plants treated with a low concentration of KIO3 (5 mg/l) showed an increase in the leaf dry weight, total protein and soluble sugars content with respect to no KIO3 supply under salinity stress. Additionally, low concentration of KIO3 raised free radical scavenging activities of strawberry leaf because of an enhancement of total phenolic content as well as CAT activity. In contrast, plants supplemented by 50 mg/l KIO3 exhibited an extreme stress for the photosynthetic parameters ofstrawberry, as demonstrated by the changes in the Fv/Fo as well as higher levels of MDA was similar to that observed in salt treatments. While KIO3 at 5 mg/l could increase photosystem performance index under salt-stress conditions in addition to the stimulation of antioxidant system, KIO3 at 50 mg/l could not ameliorate the negative effect of salt on strawberry and led to toxicity and caused damage to photochemical reactions, which is mainly overlooked by other authors.