The reactive influences of pre-sowing He-Ne laser seed irradiation and drought stress on growth, fatty acids, phenolic ingredients, and antioxidant properties of Celosia argentea

Abstract

Drought stress possesses a destructive effect on crop productivity and food security worldwide. Recently, the protective role of He-Ne laser radiation in plants against different abiotic stresses has been reported. However, there is no information about the protecting role of He-Ne laser irradiation against drought stress in Celosia argentea. Accordingly, the protective effect of different exposure times (0, 5, 10, and 15 min) of He-Ne laser irradiation in C. argentea exposed to different irrigation regimes (4, 7, and 10 days) was investigated for the first time. The branches number, root length, and vase life days, besides the fatty acids profile, total contents of phenolic, flavonoid and tannin compounds, as well the antioxidant activity of C. argentea methanol extracts using DPPH and ABTS assays were positively affected by the He-Ne laser irradiation exposure time as compared to 0 min exposure time (L0). Regarding the combination of He-Ne laser radiation and irrigation regime, the L5 and L10 enhanced most of the growth parameters especially with 4 and 7 days drought regimes (D4 and D7). The L0 + D4 exhibited the highest amount of total identified fatty acids (TFA) and saturated fatty acids (SFA) and the lowest amount of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), besides the L5, L10, and L15 exposure times showed a positive effect against 10 days irrigation regime (D10) by increasing the contents of polyphenolic compounds and antioxidant activity in C. argentea. Hesperidin (580.03 μg/g, DW), acacetin 7-O-rutinoside (222.54 μg/g, DW), apigenin-6-arabinose-8-galactose (216.91 μg/g, DW), and quercetin (49.82 μg/g, DW) are the major flavonoids were identified and quantified by HPLC in C. argentea. These findings could propose the He-Ne laser as a new, low cost, and safe method for guarding plant cells against negative effects of drought stress. The L10 followed by L5 is the most effective exposure times of laser that induced drought tolerance on C. argentea through increasing branches number, root length, and vase life days and giving the highest concentration of secondary metabolites.