Benefit of iodine soil application for alleviating detrimental effects of salinity stress in strawberry

Since the photochemical mechanisms of iodine-mediated adaptation to salt stress is not yet clear, the present study was performed to address this issue. Strawberry (Fragaria × ananassa Duch.) plants were grown under controlled conditions, and soils of iodine treatment were fertilized with potassium iodate (KIO
3 (5 and 50 mg/kg soil) before filling the pots. Salt stress (50 mM) negatively affected protein synthesis and photochemical reactions of strawberry, as evaluated by a decrease in performance index (PI
absas well as higher levels of hydrogen peroxide (H2O2) and malondialdehyde, whereas application of KIO
3
(at both 5 and 50 mg/kg) alleviated the detrimental effect of sodium chloride (NaCl) stress. Plants treated with 50 mg/kg showed an increase in the soluble sugars content with respect to no KIO
3
supply under salinity stress. In salt-stressed plants, the OJIP chlorophyll fluorescence curve showed a quicker fluorescence decrease in the I-P phase. Notably, I-P phase in plants treated with KIO
3
was increased. These results indicated that KIO
3
application could protect the photosystem II from damage under salinity stress. Additionally, application of KIO
3
raised free radical scavenging activities of strawberry leaf because of an enhancement of catalase activity. These data provided the first evidence that the root-applied KIO
3
pretreatment alleviated salt stress in strawberry by decreasing reactive oxygen species production, resulting in better photochemical functioning under salt stress