Elemental, biochemical and essential oil modulation in developing seedlings of Psoralea corylifolia L. exposed to different presowing gamma irradiation treatment

Seeds of Psoralea corylifolia L. were irradiated with different doses of gamma rays; 2.5, 5, 10, 15 and 20 kGy from a cobalt source a at dose rate of 1.65 kGy/hour. The stimulatory effects of gamma irradiation at 10 kGy were evident for biochemical and elemental parameters at the flowering stage and thereafter declined. Nitrogen was found to be maximum in leaves and sulfur in roots at the flowering stage of seedlings grown from seeds exposed to 10 kGy. Sulfur content was found to be most sensitive to gamma irradiation doses resulting in a maximum decline in stems (89.10%), leaves (65.79%) and roots (57.07%) with 20 kGy, respectively. Amino acids exhibited a similar percent decline (52.79%) at the pre-flowering stage in plants raised from seeds irradiated with 20 kGy. Using gas chromatography–mass spectrometry (GC–MS) and solid-phase particle microextraction (SPME) analysis, a remarkable percent increment was confirmed in tricyclene, α-pinene, β-myrcene, camphene, caryophyllene, β-gurgenene, n -nonanal, β-(E)-ocimene, (Z)-3-hexene-ol and germacrene D in plants raised from seeds exposed to 20 kGy. Maximum oil content (1.60%) was found in seeds irradiated with 20 kGy and minimum oil content was found in control seeds (0.89%). The study demonstrates the inverse response between primary and secondary metabolites in terms of enhancement in essential oil yield, as well as concentration of antioxidant components at 15 and 20 kGy.