Effect of Osmopriming with Melatonin on Germination, Vigor and Health of Daucus carota L. Seeds

Carrot is one of the most frequently grown vegetables in Poland and in the world. Seed-borne pathogenic fungi negatively influence their quality as well as the quantity and quality of carrot root yield. Melatonin is a PGR, which includes protective effects against biotic and abiotic stress factors and antioxidant effects. The aim of this experiment was to determine the effect of osmopriming with melatonin on germination, vigor and carrot seeds health. Carrot seeds were osmoprimed in a solution of polyethylene glycol (PEG) with an osmotic potential of −1.5 MPa at 20 °C for 7 days; melatonin was added to the PEG solution at doses of 25, 50, 100 or 200 µM. Generally, osmopriming with the addition of melatonin significantly improved germination capacity at first and final counts (sample I about 7–14% and sample II 35–43%), reduced the incidence of Alternaria alternata, A. radicina and Fusarium spp. and increased the percentage of non-sporulating hyphae. Treating accelerated the germination of seeds at a significant rate in comparison with untreated seeds and treated with fungicide, especially at low dosage, i.e., 25–50 µM. MGT of primed seeds with the addition of melatonin at dose 25 µM shortened about 0.5 day (sample I) and 1 day (sample II) The effect of melatonin on seed quality parameters was comparable or better than treating with fungicide. The results suggest that melatonin could replace fungicides in the future, which are harmful to the environment.