Cold argon plasma (CAP)-assisted seed priming to improve germination metrics of Ferula assa-foetida, an endangered medicinal plant

• The priming roles of four exposure times of cold argon plasma (control, CAP1-3) on the seed germination and growth parameters of Ferula assa-foetida were studied at 1 °C or 5 °C. • CAP1-3-primed seeds yielded higher imbibition values of 80 %, particularly in the first 30 min of incubation at room temperature. • The values of germination metrics and seedling growth criteria varied among all eight treatments, depending on CAP exposure time and temperature. • The heatmap clustering divided eight treatments into two categories, each one contained four CAP-primed seed groups incubated at 1 °C or 5 °C. • Using SIIT parameter that converts all 15 studied traits into a singular value, 5 °C+CAP3 treatment exhibited the best performance with the highest SIIT score (0.61). The potential impact of cold argon plasma (CAP) and temperature on the seed germination process of Ferula assa-foetida was studied using factorial design with two factors of CAP exposure time (Zero, 30 s, 60 s, and 90 s, referred to as Control, CAP1, CAP2, and CAP3, respectively) and temperature (1.0 and 5.0 °C) based on a completely randomized design (CRD) with three replicates. The imbibition test results showed significant difference between the CAP-primed and non-primed seed groups, with all three CAP treatments absorbing over 80 % water in just 30 min. The final germination percentage (FGP) ranged from 51.11 % to 82.22 % for 1 °C+Control and 5 °C+CAP3 treatments, respectively. These results were further supported by the findings of four-parameter hill function (FPHF) model, where the area under the curve (AUC) ratio ranging from 1149.85 to 738.89 for 5 °C+CAP3 and 1 °C+Control groups, respectively. Meanwhile, 1 °C+Control treatment exhibited minimum values for seedling vigor index I and II (1.79 and 0.19, respectively), while 5 °C+CAP3 treatment yielded the highest values (7.88 and 0.42, respectively). According to the results of the “ selection index of ideal treatment ” ( SIIT ), the 5 °C+CAP3, 1 °C+CAP3 and 5 °C+CAP2 were identified as the top three superior options with maximum SIIT values of 0.61, 0.54 and 0.52, respectively. Conversely, 1 °C+CAP1 and 5 °C+Control treatments had the lowest SIIT values of 0.40 and 0.42, respectively. Overall, this study highlighted the potential use of CAP as a valuable, eco-friendly, and sustainable green priming tool for promoting the germination capacity/uniformity, growth, and preservation of this endangered medicinal plant, and possibly others, as well.