Influence of Contained Cold Plasma Processing on Multi‐Species Sward Seeds Germination and Plant Growth Performance Properties

ABSTRACT

Multi‐species Swards (MSS) grasslands are recognized for mitigating agriculture‐associated emissions, but the establishment and maintenance of MSS profiles remain challenging due to variable germination and early seedling growth. In this study, cold plasma priming of MSS was evaluated by comparing germination and seedling performance of MSS seeds, including grasses (ryegrass, timothy), herbs (chicory, plantain), and legumes (red clover, white clover). Seeds were treated in a DBD reactor using air as the input gas at voltage levels of 50–70 kV for 10–30 s. Treatments produced species‐specific responses, with significant ( p  ≤ 0.05) increases in surface nitrite and hydrogen peroxide concentrations, pH, electrolyte leakage, germination percentage (GP), seed vigor index (SVI), shoot/root length, and photosynthetic pigment concentration. Treatments at 60 kV 10–30 s, delivered consistent improvements across the MSS seed mix, increasing GP% by 10%–23% and SVI by 11%–47% compared to untreated seeds. Higher intensity treatment with 70 kV 30 s further enhanced seedling performance in red clover and ryegrass, however, it negatively affected white clover and timothy seeds. Overall, cold plasma priming displayed strong potential to improve establishment patterns within MSS under these controlled conditions, which provided treatment conditions for individual seed species prior to mixing or sowing.