The effects of hydro- and osmopriming on the germination, vigour and hydrolytic enzymes activity of common zinnia (Zinnia elegans Jacq.) seeds

Priming is one of the most common methods of improving seed quality. The aim of this experiment was to study the effects of hydro- and osmopriming on the germination, vigour and hydrolytic enzymes (α-amylase, β-glucosidase, exopeptidase and lipases) activity of zinnia (Zinnia elegans Jacq.) seeds. Seeds of three cultivars: Jowita, Kirke and Orys, and Z. elegans fl.pl., a mixture of cultivars (Mix), were tested. The seeds were hydroprimed in a restricted volume of water (200 μl H₂O g⁻¹ seed, 24 h at 15°C) and osmoprimed in a polyethylene glycol solution (−1.0 MPa PEG 8000, 5 days at 20°C). Untreated seeds served as the control. The cultivars differed significantly in terms of seed quality as well as response to priming. On average, ‘Jowita’ seeds were characterised by the highest quality, expressed by the total number of germinating seeds (G_max) and germination at the 1^st and 2^nd counts. Mix seeds showed the lowest quality, expressed by germination at the 1^st and 2^nd counts and vigour. Generally, an increase in α-amylase activity and a decrease in lipase activity was found in hydroprimed and osmoprimed seeds, and α-amylase activity was significantly higher in ‘Jowita’ seeds than Mix seeds. The applied treatments did not affect β-glucosidase and exopeptidase activity in the tested seeds. Osmopriming accelerated seed germination and influenced α-amylase and lipase activity to a greater extent than hydropriming. Among the assayed enzymes, only the activity of α-amylase may be potentially useful for the seed industry as a physiological marker of zinnia seed vigour and the effectiveness of osmopriming.