Effect of melatonin and hydropriming on germination of aged triticale and rye seeds

The formation of reactive oxygen species, which initiate lipid peroxidation of membranes and disruption of all membrane-associated processes, is one of the critical factors causing seed senescence and loss of germinability. Melatonin is currently considered one of the powerful antioxidant bioregulators that influence many plant functions, including their resistance to stress factors and seed germination. However, the effect of melatonin on the germination of old triticale and rye seeds has not been specifically investigated. The work aimed to study the effect of melatonin treatment and the well-known procedure of hydropriming (soaking in water with subsequent drying of seeds) on the germination of seeds of triticale ‘Raritet’ and rye ‘Pamyat Khudoerka’ with low germination capacity and the state of antioxidant system in seedlings. Hydropriming had a small but significant effect on the germination of triticale seeds at p ≤ 0.05 and significantly increased the germination of rye seeds. Melatonin treatment positively impacted both crop seed germination and significantly exceeded the effects of hydropriming. The most significant effect was observed when melatonin was used at a concentration of 20 μM. The accumulation of shoot and root biomass also increased under hydropriming and (to a greater extent) melatonin. Melatonin treatment led to a significant decrease in the generation of superoxide anion radical and the content of hydrogen peroxide and malonic dialdehyde, a product of lipid peroxidation, in seedlings of both crops. Additionally, melatonin increased the activity of superoxide dismutase and catalase in both crops. The anthocyanin content increased in the seedlings of both cereals under the influence of melatonin. The effect of hydropriming on indicators characterising the prooxidant and antioxidant balance was insignificant. A conclusion was drawn on the ability of exogenous melatonin to enhance the germination of old triticale and rye seeds and the connection of this effect with the regulation of the antioxidant system.