Hydrotime analysis to explore the effect of H2O2-priming in the relationship between water potential (Ψ) and germination rate of Capsicum annuum L. seed under NaCl- and PEG-induced stress.

Abstract 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 H2O2−primed seeds in progress toward germination. Pre−optimized H2O2 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 H2O2−priming affects differently the three derived items of HT model; induced lower hydrotime constant (θH) thus, revealed more rapid germination particularly evident with PEG, shifted the threshold or base water potential for 50% germination (Ψb(50)) 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 (σΨb), proved a better uniformity of the germination process for both cultures. Thus, H2O2−priming increased GRg (1/tg) at all Ψ>Ψb(g) which is due to both a lower Ψb(50) and a smaller θH in the primed seeds for NaCl culture and primarily owing to reducing θH with no positive effect on Ψb(50) for PEG culture. A normalized time−scale, for comparing responses, was introduced and confirmed the aforementioned impact. Therefore, the crosstalk between H2O2 molecule and different cell pathways generates a constructive response in accordance with imposed stress.