Effect of seed treatment with UV radiation on Marjoram (Origanum majorana L.) active ingredients under saline conditions (Origanum majorana L or Majorana hortensis Moench.)

Abstract

Abstract In a pot experiment, the dry seeds of the Sweet Marjoram plant ( Origanum majorana L.) were exposed to ultraviolet UV-C (254 nm) light for 30 and 60 min. They were subjected to salinity conditions (4 and 6 dS/m). Plants were evaluated, determining total chlorophyll (SPAD), oil content, and active components in the vegetative phenotypes. The results showed that plants grown under UV for 60 min increased plant height by 67.5% and fresh weight (FW) by 45.5% compared to the corresponding control under non-saline conditions. Similarly, exposing seeds to UV-C for 60 min increased the total chlorophyll group by 52% at 6 dS/m. They were less affected by salt stress, while treating them for 30 min improved the number of branches and leaves under non-saline conditions. Additionally, it helped plants protect themselves by shielding them from osmotic shock. Also, Ultraviolet rays led to a reduction in lipid peroxidation malondialdehyde (MDA) levels and increased the total phenols concentration under UV for 60 min, despite their growth being better than that of the control group. However, treating seeds with UV light for 60 min enhanced the biosynthesis of essential oils in plants. Also, GC–MS analysis detected a total of 30 compounds. Nevertheless, the major components were trans-Sabinene hydrate, terpinen-4-ol, γ-terpinene, α-terpineol, terpinolene, and β-myrcene. In general, it can be concluded that treating marjoram seeds with UV-C light stimulated the plant's ability to tolerate salt stress by activating the antioxidant system.