Effect of priming on germination indices of deteriorated seeds of pumpkin (Cucurbita pepo) in salinity conditions

In order to investigate the effect of priming on germination characteristics of aged pumpkin seeds, under salinity stress an experiment was performed as a factorial design in a completely randomized design with 4 replications. Experiment was done in the Seed Science and Technology Laboratory of the Faculty of Agriculture and Natural Resources, Mohaghegh Ardabili University. Treatments included seed deterioration (control, 85% and 75%), salinity stress (zero, 75 and 150 mM), and priming (control, hydropriming, gibberellin, Gr24, benzyl-aminopurine, and spermidine). The results showed that salinity stress and seed deterioration reduced germination percentage, root length, stem length, relative water content (RWC), protein and carotenoids so that salinity treatment of 150 mmol, degree of 75 % seed deterioration  showed the lowest percentage of these traits. Also, the activity of CAT, POX and SOD due to seed deterioration was 75% lower than other treatments. While priming with spermidine was able to significantly increase the amount of these enzymes in conditions of high salinity MDA, which is one of the most important results of stress, decreased under salinity stress and aging, but seed priming decreased MDA sharply, especially in priming with spermidine. In addition, seed priming was able to significantly reduce the effects of salinity stress and seed deterioration so that the percentage of germination and protein in increased gibberellin priming, root and shoot length in priming with Gr24, as well, and RWC and carotenoids in priming Spermidine. Salinity stress applied on deteriorated seeds led to disruption and reduction in physiological traits, while seed priming by different methods led to a reduction and improvement of adverse stresses.