Investigating Seed Germination, Seedling Growth, and Enzymatic Activity in Onion (Allium cepa) Under the Influence of Plasma-Treated Water

TL;DR

Plasma-treated water boosts onion seed germination and seedling growth by enhancing redox signaling and hormone regulation, offering a sustainable alternative to agrochemicals.

Contribution

Demonstrates plasma-treated water as an eco-friendly method to enhance germination and seedling growth through NO-enriched redox signaling and hormonal regulation.

Findings

Plasma-treated water increased germination rates beyond 98% and improved seedling biomass and growth.

Transcriptomic analysis showed upregulation of gibberellin biosynthesis and antioxidant defense genes.

PTW altered NO2−, NO3−, and hydrogen peroxide levels, supporting redox signaling and stress resilience.

Abstract

Seed germination and early seedling growth are pivotal stages that define crop establishment and yield potential. Conventional agrochemicals used to improve these processes often raise environmental concerns, highlighting the need for sustainable alternatives. In this study, we demonstrated that water treated with cylindrical dielectric barrier discharge (c-DBD) plasma, enriched with nitric oxide (NO) and reactive nitrogen species (RNS), markedly enhanced onion (Allium cepa) seed germination and seedling vigor. The plasma-treated water (PTW) promoted rapid imbibition, broke dormancy, and accelerated germination rates beyond 98%. Seedlings irrigated with PTW exhibited significantly increased biomass, root and shoot length, chlorophyll content, and antioxidant enzyme activities, accompanied by reduced lipid peroxidation. Transcriptomic profiling revealed that PTW orchestrated a multifaceted regulatory network by upregulating gibberellin biosynthesis genes (GA3OX1/2), suppressing abscisic acid signaling components (ABI5), and activating phenylpropanoid metabolic pathways (PAL, 4CL) and antioxidant defense genes (RBOH1, SOD). These molecular changes coincided with elevated NO2− and NO3− levels and finely tuned hydrogen peroxide dynamics, underpinning redox signaling crucial for seed activation and stress resilience. Our findings establish plasma-generated NO-enriched water as an innovative, eco-friendly technology that leverages redox and hormone crosstalk to stimulate germination and early growth, offering promising applications in sustainable agriculture.

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