Hydrotime analysis to explore the effect of HO-priming in the relationship between water potential (Ψ) and germination rate of Capsicum annuum L. seed under NaCl- and PEG-induced stress.

Hydrogen peroxide (H2O2) priming was proved to be effective to boost salt and drought stress tolerance in Capsicum annuum L. Hither, hydrotime (HT) approach, a population-based threshold model-germination dependence on water availability, was introduced to account for the effects of reduced water potential on HO-primed seeds in progress toward germination. Pre-optimized HO concentrations (1 and 10 mM for 24 h at 25 °C) were applied. Subsequently, seeds were germinated over a range of water potential (Ψ) (0 to -1.2 MPa) induced by sodium chloride (NaCl) and polyethylene glycol (PEG-6000) at 25 °C. We suggest that HO-priming affects differently the three derived items of HT model; induced lower hydrotime constant (θ) thus, revealed more rapid germination particularly evident with PEG, shifted the threshold or base water potential for 50% germination (Ψ) towards a more negative value in NaCl culture, reflected a better salinity tolerance, though, the opposite effect was recorded with PEG, and reduced the standard deviation (σ), proved a better uniformity of the germination process for both cultures. Thus, HO-priming increased GR (1/t) at all Ψ>Ψ which is due to both a lower Ψ and a smaller θ in the primed seeds for NaCl culture and primarily owing to reducing θ with no positive effect on Ψ for PEG culture. A normalized time-scale, for comparing responses, was introduced and confirmed the aforementioned impact. Therefore, the crosstalk between HO molecule and different cell pathways generates a constructive response in accordance with imposed stress.