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 (θ_H) thus, revealed more rapid germination particularly evident with PEG, shifted the threshold or base water potential for 50% germination (Ψ_b(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 (σ_Ψb), proved a better uniformity of the germination process for both cultures. Thus, H₂O₂-priming increased GR_g (1/t_g) at all Ψ>Ψ_b(g) which is due to both a lower Ψ_b(50) and a smaller θ_H in the primed seeds for NaCl culture and primarily owing to reducing θ_H with no positive effect on Ψ_b(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.

Keywords: Base water potential; Capsicum; Drought; H(2)O(2)−priming; Hydrotime analysis; Salinity.