Résumé:
Salinity is a major abiotic stress affecting crops and plants production. Oxidative stress associated with it is often caused by excessive generation of reactive oxygen species. One of the mechanisms of non-enzymatic defense against stress that plants adopt is the production of phenolic compounds considered as antioxidants.
This investigation is carried out with the aim to study the variability of the levels of total polyphenols and flavonoids in bean (Vicia faba L.) in response to salt stress induced by irrigation with solutions of increasing salinity based on combination of NaCl and CaCl2 salt (25, 50, 75 and 100 mM . L-1) in plastic pots under semi-controlled conditions.
The results showed that, in stage1 the total polyphenol content of the aerial parts methanolic extracts (stems and leaves) vary non-significantly with the rate of salts with a maximum increase of 18% in T1. In stage 2, we recorded an increase in T2, T3 and T4 with a significant difference in T4 (+ 29%) compared to the control T.
The content of flavonoids reduced by the elevated levels of salts and exhibit significant variations in T2 (-56%) for the stage1, and rate of decline of -38% and -27% in T2 and T3 respectively for the stage 2.
The antioxidant DPPH test revealed that the IC50 extracts decreases with increasing salt concentration. In stage 1, significant decreases were recorded in T2 (-68%), T3 (56%) and T4 (-52%). In stage 2, the decreases are significant in T3 (-37%) and T4 (-36%). So overall, antioxidant potential increases with increasing salt stress.
