Seed priming with two types of glassy microparticles in cowpea subjected to water deficit induced by polyethylene glycol 6000

The relevance of cowpea (Vigna unguiculata (L.) Walp.) in semi-arid regions drives the search for drought tolerance strategies. Our hypothesis was that seed priming with glassy silicon microparticles (SiMPs), a low-cost recycled glass byproduct, confers comprehensive resilience, functioning as both a biostimulant under optimal conditions and a structural and metabolic protector under drought stress. METHODS: The experiment was conducted in a 4 × 2 factorial design, with four primings: Control (water), P1 (Ψs = -0.4 MPa with PEG 6000), P2 (P1 + Blue SiMPs), and P3 (P1 + Amber SiMPs), applied to 'BRS Tapaihum' cowpea seeds and at two water replacement levels (35% and 75% of ETc), with five replicates. RESULTS: Priming with P1 (PEG 6000) was ineffective at mitigating stress (W35), resulting in lower TDM values and higher oxidative stress (SOD and CAT). In contrast, SiMPs demonstrated bifunctional benefits, as under optimal conditions (W75), P2 acted as a biostimulant, increasing TDM by 18%. Under stress (W35), P3 and P2 conferred protection through membrane stabilization (30% reduction in electrolyte leakage (EL) and optimization of WUEi compared to P1), resulting in TDMs up to 25% higher than the control under W35. CONCLUSIONS: Priming with SiMPs (blue and amber) is an effective strategy, conferring comprehensive resilience by optimizing WUEi at W75 and structurally protecting membranes at W35, in contrast to the insufficiency of PEG 6000. The use of this recycled glass material constitutes a sustainable and low-cost solution with significant potential to increase productivity and food security in semi-arid regions.