# Growth and Hormonal Responses to Salicylic Acid and Calcium Chloride Seed Priming in Domestic and Wild Salt-Tolerant Barley Species Under Saline Conditions

## TL;DR

This study explores how seed priming with salicylic acid and calcium chloride helps domestic and wild barley species grow better under salty conditions.

## Contribution

The novel aspect is comparing hormonal responses in domestic and wild barley species under salinity stress after seed priming.

## Key findings

- Domestic barley showed higher growth recovery with salicylic acid priming under high salinity.
- Wild barley exhibited intrinsic salt tolerance linked to high hormone levels.
- Priming altered hormonal profiles, especially reducing ABA and increasing growth hormones in domestic barley.

## Abstract

Salinity is among the main abiotic constraints limiting crop productivity worldwide. Salt tolerance can be improved by introducing adaptive traits from wild species and enhancing pre-existing salt-adaptive mechanisms through priming. This study evaluated the beneficial effect of salicylic acid (SA, 1.25 mM) and calcium chloride (CaCl2, 5 mM) seed priming on plant growth under salinity in the domestic barley Hordeum vulgare (Hv) and the wild, salt-adapted Hordeum maritimum (Hm). Primed plants were grown under control, 100 and 200 mM sodium chloride (NaCl) for two weeks. Growth and hormone profiling were performed. Hv showed higher growth inhibition than Hm but was more responsive to stress alleviation by priming, particularly with SA, which increased biomass by up to 47% at 200 mM NaCl. The contrasting responses of both species reflected distinct hormonal strategies. The intrinsic salt tolerance of Hm appears linked to high constitutive levels of stress- and growth-related hormones. In Hv, growth recovery under salinity following priming was associated with hormonal reprogramming, involving reduced abscisic acid (ABA) accumulation and enhanced levels of growth-promoting hormones (indole-3-acetic acid (IAA), trans-zeatin (tZ), and isopentenyl adenine (iP)), especially in roots. Hormonal changes mediated by priming are analyzed in relation to adaptive growth responses and species’ ecological origins.