Priming Strategies for Parsley Seedling Production

Parsley seeds are known for nonuniform and long germination; consequently, vegetable nurseries commonly use priming techniques to improve the production of parsley seedlings. The objectives of this study were 1) to characterize the imbibition curve of parsley seeds, 2) to evaluate the effect of different priming agents on parsley seedling production, and ultimately 3) to compare priming techniques for emergence and vigor of parsley’s seedlings, thus providing an optimal priming strategy for parsley seedling production. Using three priming agents—water (seeds imbibed for 24, 48, 72, and 96 hours), polyethylene glycol 6000 (PEG6000) (seeds imbibed at –0.5, –1.0, –1.5, and –2.0 MPa for 29, 58, 87, and 116 hours), and gibberellic acid (GA) (seeds imbibed at 0.5, 1.0, 1.5, and 2.0 g·L−1 a.i. of solution for 15, 30, 45, and 60 minutes), and two parsley cultivars (Krausa and Titan), three experiments evaluated parsley seedling parameters, including emergence speed index (ESI) and total emergence (TE) in a complete randomized block design (n = 4) each. In Expt. 1 (hydropriming), increasing water imbibition time (IT) reduced ESI on both parsley cultivars. In addition, the TE quadratically reduced with the increase of water IT. In Expt. 2 (osmopriming), there was no significant main effect or interaction of treatments on ESI. Regardless of PEG6000 concentration, the TE had a linear increase with the increase of IT for cultivar Krausa but not for cultivar Titan. In Expt. 3 (hormonal priming), there was a significant increase in ESI and TE with the increase in GA rate. Ultimately, strategies for analysis of best priming were water at 24 hours of IT, PEG6000 at –2.0 MPa for 116 hours of IT, and GA at 2.0 g·L−1 a.i. of solution for 15 minutes of IT. Once compared with an untreated seeds treatment, priming strategies of water imbibition for 24 hours and PEG6000 at –2.0 MPa for 116 hours had the highest ESI and TE.