Effect of priming on germination traits and antioxidant enzymes of pumpkin (Cucurbita pepo L.) seeds with different vigor under drought stress

Abstract

In order to investigate the effect of priming on aspects of germination of aged pumpkin seeds under drought stress, a factorial experiment was conducted based on a completely randomized design with four replications in the laboratory. Treatments included of aging (control, 85% and 75% of control germination), drought stress (0, -0.75 and -1.5 MPa), and priming (control, hydro, gibberellin, GR24, benzyl aminopurine and spermidine). Results of mean comparison showed that the lowest germination percentage (43.6%), protein (0.82 mg.g-1Fw), radical length (RL, 9.24 mm), plumule length (PL, 1.19 mm), relative water content (RWC, 35.5%), carotenoid (1.253 mg.g-1Fw), catalase (CAT, 7.03 µmol.gmin-1.mgprotein-1), peroxidase (POX, 47.72 µmol.gmin-1.mgprotein-1) and superoxide dismutase activity (SOD, 53.48 mmol.gmin-1.mgprotein-1) were related to drought treatment with an intensity of -1.5 MPa and with 75% aging in the absence of priming. Also, the lowest content of malone dialdehyde (MDA, 3.75 mmol.g-1Fw) and proline (1.573 µg.g-1Fw) were obtained in the absence of drought and aging with priming by spermidine. The highest germination percentage (98.03%) and protein (9.54 mg.g-1Fw) were obtained in gibberellin treatment, RL (15.73 mm) and PL (4.26 mm) in priming with GR24 hormone, RWC (83.64%), carotenoid (6.277 mg.g-1Fw), CAT (40.44 µmol.gmin-1.mg protein-1), POX (95.71 µmol.gmin-1.mgprotein-1) and SOD activity (131.68 µmol.gmin-1.mg protein-1) in priming with spermidine with Non-drought stress and aging conditions. The highest MDA (32.42 mmol.g-1Fw) and proline (0.55 µg.g-1Fw) were observed in drought with an intensity of -1.5 MPa and 75% aging in the absence of priming.