Improving Germination and Salinity Tolerance in Snail Medic (Medicago scutellata L.) Through Hydrogen Peroxide (H2O2) Seed Priming

Salinity is a major environmental constraint that limits agricultural productivity, particularly in arid and semi-arid regions. This study investigated the effects of hydrogen peroxide (H 2 O 2 ) seed priming on germination and early seedling growth of snail medic ( Medicago scutellata L.) under salinity stress. A factorial germination experiment was conducted using H 2 O 2 concentrations of 0, 20, 40, 60, 80, and 100 μM across salinity levels of 0, −3, −6, −9, and −12 MPa. Salinity stress significantly affected key ecological traits, including weight of mobilized seed reserve (WMSR), seed reserve depletion percentage (SRDP), seedling growth rate (SLGR), seed reserve utilization efficiency (SRUE), root length (RL), shoot length (SL), and the activities of antioxidant enzymes catalase (CAT), peroxidase (PER), superoxide dismutase (SOD), and ascorbate peroxidase (APX). The highest RL values were observed at 20 and 40 μM H 2 O 2 , measuring 5.75 and 5.31 mm, respectively. Maximum WMSR (0.145 mg seed-1) and SLGR (0.023 mg d-1) were recorded at 40 μM H 2 O 2 , representing increases of 2.07% and 15.6% compared with the control. Interaction effects indicated that H 2 O 2 concentrations up to 80 μM alleviated the negative impacts of salinity on seedling growth, whereas increasing salinity from −9 to −12 MPa caused more complex responses in ecological traits and enzyme activities. A strong positive correlation was observed between WMSR and SLGR, with a one-unit increase in WMSR leading to a 7.53% increase in SLGR (R = 0.87**). The highest WMSR (0.174 mg seed-1) occurred at 20 μM H 2 O 2 under −3 MPa salinity. Overall, H 2 O 2 seed priming improved seedling growth and stress tolerance, highlighting its potential for enhancing the establishment of forage species in saline environments.