Salicylic acid and fish flour pre-treatments affect wheat phenolic and flavonoid compounds, lipid peroxidation levels under salt stress

The potential effect of combined salicylic acid and fish flour to improve plant tolerance to salt stress was investigated. This pre-treatment improved the growth of wheat seedlings under salinity when compared to control (untreated wheat seedlings). Moreover, combined pre-treatment improved significantly phenylalanine ammonia lyase (PAL) and peroxidase (POD) enzyme activities, also phenolic-flavonoid content in the shoots of salt stressed seedlings. One of the most important consequences of increase in salt stress is the oxidative tissue damage. In our study, salt stress increased lipid peroxidation levels (LPO) and also the loss of chlorophylls levels during stress might also be related to photo-oxidation resulting from oxidative stress. Whereas phenylalanine ammonia-lyase (PAL) activities of wheat shoots increased by a 2.1-fold under salt stress, the activities of shoots grown from seeds primed with salicylic acid and fish flour (SA + FF) increased by a 4-fold for 0.05 mM SA + FF, 4.8- fold for 0.1 mM SA + FF and 3.7-fold for 2.5 mM SA + FF combined pre-treatment under salt stress. Also, the combined salicylic acid + fish flour primed seedlings showed higher content of the scopoletin, and salicylic, syringic, vanilic and gallic acids under both salt and nonsalinity stress conditions