Osmopriming mitigates the adverse effects of water deficit on seed germination of Mimosa caesalpiniifolia Benth.

Abstract

Water deficit is a major constraint to seed germination and plant establishment, particularly in semi-arid environments. Seed priming has emerged as a promising strategy to improve seed performance under adverse water conditions. This study evaluated the effects of osmopriming on the germination of Mimosa caesalpiniifolia Benth. seeds subjected to different water potentials. The experiment was conducted in a completely randomized design using a 3 × 5 factorial scheme, consisting of three priming treatments (unprimed seeds, PEG-6000 at -1.0 MPa, and KNO₃ at 100 mM) and five water potentials (0.0, -0.5, -1.0, -1.5, and -2.0 MPa), with four replicates of 25 seeds. Germination percentage, germination speed index, and mean germination time were evaluated. Water deficit progressively reduced germination percentage and germination speed while increasing mean germination time. Osmopriming partially attenuated these effects, particularly under moderate water deficit. At -1.0 MPa, PEG-6000 and KNO₃ maintained higher germination percentages, while PEG-6000 promoted greater germination speed and reduced mean germination time. However, under severe water deficit (-1.5 and -2.0 MPa), the protective effects of priming were substantially reduced. These findings indicate that osmopriming, particularly with PEG-6000, can improve the germination performance of M. caesalpiniifolia under moderate water limitation.